JAVA-12421 Renamed graphql to graphql-modules

2022-06-03 18:00:47 +05:30
parent 4413c8d66d
commit db663d2033
81 changed files with 12 additions and 11 deletions
@@ -0,0 +1,7 @@
+## GraphQL Domain Graph Service (DGS)
+
+This module contains articles about GraphQL using the Netflix Domain Graph Service (DGS).
+
+## Relevant articles:
+
+- [An Introduction to Domain Graph Service (DGS) Framework](https://www.baeldung.com/spring-boot-domain-graph-service)
@@ -0,0 +1,73 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>graphql-dgs</artifactId>
+    <version>1.0</version>
+    <name>graphql-dgs</name>
+
+    <parent>
+        <groupId>com.baeldung.graphql</groupId>
+        <artifactId>graphql-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>com.netflix.graphql.dgs</groupId>
+                <artifactId>graphql-dgs-platform-dependencies</artifactId>
+                <version>4.1.0</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.netflix.graphql.dgs.codegen</groupId>
+            <artifactId>graphql-dgs-codegen-client-core</artifactId>
+            <version>${graphql-dgs-codegen-client-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.netflix.graphql.dgs</groupId>
+            <artifactId>graphql-dgs-spring-boot-starter</artifactId>
+            <version>${graphql-dgs-spring-boot-starter.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>io.github.deweyjose</groupId>
+                <artifactId>graphqlcodegen-maven-plugin</artifactId>
+                <version>1.14</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>generate</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <schemaPaths>
+                        <param>src/main/resources/schema/schema.graphqls</param>
+                    </schemaPaths>
+                    <packageName>com.bealdung.graphqldgs.generated</packageName>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <graphql-dgs-codegen-client-core.version>5.1.14</graphql-dgs-codegen-client-core.version>
+        <graphql-dgs-spring-boot-starter.version>4.9.15</graphql-dgs-spring-boot-starter.version>
+    </properties>
+
+</project>
@@ -0,0 +1,25 @@
+package com.bealdung.graphqlDGS;
+
+public class Album {
+    private final String title;
+    private final String artist;
+    private final Integer recordNo;
+
+    public Album(String title, String artist, Integer recordNo) {
+        this.title = title;
+        this.recordNo = recordNo;
+        this.artist = artist;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public String getArtist() {
+        return artist;
+    }
+
+    public Integer getRecordNo() {
+        return recordNo;
+    }
+}
@@ -0,0 +1,28 @@
+package com.bealdung.graphqlDGS;
+
+import com.netflix.graphql.dgs.DgsComponent;
+import com.netflix.graphql.dgs.DgsQuery;
+import com.netflix.graphql.dgs.InputArgument;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@DgsComponent
+public class AlbumsDataFetcher {
+
+    private final List<Album> albums = Arrays.asList(
+      new Album("Rumours", "Fleetwood Mac", 20),
+      new Album("What's Going On", "Marvin Gaye", 10),
+      new Album("Pet Sounds", "The Beach Boys", 12)
+    );
+
+    @DgsQuery
+    public List<Album> albums(@InputArgument String titleFilter) {
+        if(titleFilter == null) {
+            return albums;
+        }
+        return albums.stream()
+                .filter(s -> s.getTitle().contains(titleFilter))
+                .collect(Collectors.toList());
+    }
+}
@@ -0,0 +1,13 @@
+package com.bealdung.graphqlDGS;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+}
@@ -0,0 +1 @@
+server.servlet.context-path=
@@ -0,0 +1,9 @@
+type Query {
+    albums(titleFilter: String): [Album]
+}
+
+type Album {
+    title: String
+    artist: String
+    recordNo: Int
+}
@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Error Handling in GraphQL With Spring Boot](https://www.baeldung.com/spring-graphql-error-handling)
@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>graphql-error-handling</artifactId>
+    <version>1.0</version>
+    <name>graphql-error-handling</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.graphql</groupId>
+        <artifactId>graphql-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-spring-boot-starter</artifactId>
+            <version>${graphql-spring-boot-starter.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-tools</artifactId>
+            <version>${graphql-java-tools.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <version>${h2.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+            <version>${graphql-spring-boot-starter.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.skyscreamer</groupId>
+            <artifactId>jsonassert</artifactId>
+            <version>${jsonassert.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <graphql-spring-boot-starter.version>5.0.2</graphql-spring-boot-starter.version>
+        <graphql-java-tools.version>5.2.4</graphql-java-tools.version>
+        <jsonassert.version>1.5.0</jsonassert.version>
+    </properties>
+
+</project>
@@ -0,0 +1,46 @@
+package com.baeldung.graphql.error.handling;
+
+import com.baeldung.graphql.error.handling.exception.GraphQLErrorAdapter;
+import graphql.ExceptionWhileDataFetching;
+import graphql.GraphQLError;
+import graphql.servlet.GraphQLErrorHandler;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@SpringBootApplication
+public class GraphQLErrorHandlerApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(GraphQLErrorHandlerApplication.class, args);
+    }
+
+    @Bean
+	public GraphQLErrorHandler errorHandler() {
+		return new GraphQLErrorHandler() {
+			@Override
+			public List<GraphQLError> processErrors(List<GraphQLError> errors) {
+				List<GraphQLError> clientErrors = errors.stream()
+						.filter(this::isClientError)
+						.collect(Collectors.toList());
+
+				List<GraphQLError> serverErrors = errors.stream()
+						.filter(e -> !isClientError(e))
+						.map(GraphQLErrorAdapter::new)
+						.collect(Collectors.toList());
+
+				List<GraphQLError> e = new ArrayList<>();
+				e.addAll(clientErrors);
+				e.addAll(serverErrors);
+				return e;
+			}
+
+			private boolean isClientError(GraphQLError error) {
+				return !(error instanceof ExceptionWhileDataFetching || error instanceof Throwable);
+			}
+		};
+	}
+}
@@ -0,0 +1,29 @@
+package com.baeldung.graphql.error.handling.domain;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import java.util.ArrayList;
+import java.util.List;
+
+@Data
+@Entity
+@Builder
+@AllArgsConstructor
+@NoArgsConstructor
+public class Location {
+    @Id
+    private String zipcode;
+
+    private String city;
+    private String state;
+
+    @OneToMany(mappedBy = "location", fetch = FetchType.EAGER)
+    private List<Vehicle> vehicles = new ArrayList<>();
+}
@@ -0,0 +1,26 @@
+package com.baeldung.graphql.error.handling.domain;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.*;
+
+@Data
+@Entity
+@Builder
+@AllArgsConstructor
+@NoArgsConstructor
+public class Vehicle {
+    @Id
+    private String vin;
+    private Integer year;
+    private String make;
+    private String model;
+    private String trim;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "fk_location")
+    private Location location;
+}
@@ -0,0 +1,44 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import graphql.ErrorType;
+import graphql.GraphQLError;
+import graphql.language.SourceLocation;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class AbstractGraphQLException extends RuntimeException implements GraphQLError {
+    private Map<String, Object> parameters = new HashMap();
+
+    public AbstractGraphQLException(String message) {
+        super(message);
+    }
+
+    public AbstractGraphQLException(String message, Map<String, Object> additionParams) {
+        this(message);
+        if (additionParams != null) {
+            parameters = additionParams;
+        }
+    }
+
+    @Override
+    public String getMessage() {
+        return super.getMessage();
+    }
+
+    @Override
+    public List<SourceLocation> getLocations() {
+        return null;
+    }
+
+    @Override
+    public ErrorType getErrorType() {
+        return null;
+    }
+
+    @Override
+    public Map<String, Object> getExtensions() {
+        return this.parameters;
+    }
+}
@@ -0,0 +1,48 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import graphql.ErrorType;
+import graphql.ExceptionWhileDataFetching;
+import graphql.GraphQLError;
+import graphql.language.SourceLocation;
+
+import java.util.List;
+import java.util.Map;
+
+public class GraphQLErrorAdapter implements GraphQLError {
+
+    private GraphQLError error;
+
+    public GraphQLErrorAdapter(GraphQLError error) {
+        this.error = error;
+    }
+
+    @Override
+    public Map<String, Object> getExtensions() {
+        return error.getExtensions();
+    }
+
+    @Override
+    public List<SourceLocation> getLocations() {
+        return error.getLocations();
+    }
+
+    @Override
+    public ErrorType getErrorType() {
+        return error.getErrorType();
+    }
+
+    @Override
+    public List<Object> getPath() {
+        return error.getPath();
+    }
+
+    @Override
+    public Map<String, Object> toSpecification() {
+        return error.toSpecification();
+    }
+
+    @Override
+    public String getMessage() {
+        return (error instanceof ExceptionWhileDataFetching) ? ((ExceptionWhileDataFetching) error).getException().getMessage() : error.getMessage();
+    }
+}
@@ -0,0 +1,7 @@
+package com.baeldung.graphql.error.handling.exception;
+
+public class InvalidInputException extends RuntimeException {
+    public InvalidInputException(String message) {
+        super(message);
+    }
+}
@@ -0,0 +1,14 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import java.util.Map;
+
+public class VehicleAlreadyPresentException extends AbstractGraphQLException {
+
+     public VehicleAlreadyPresentException(String message) {
+         super(message);
+     }
+
+    public VehicleAlreadyPresentException(String message, Map<String, Object> additionParams) {
+        super(message, additionParams);
+    }
+}
@@ -0,0 +1,14 @@
+package com.baeldung.graphql.error.handling.exception;
+
+import java.util.Map;
+
+public class VehicleNotFoundException extends AbstractGraphQLException {
+
+    public VehicleNotFoundException(String message) {
+        super(message);
+    }
+
+    public VehicleNotFoundException(String message, Map<String, Object> params) {
+        super(message, params);
+    }
+}
@@ -0,0 +1,9 @@
+package com.baeldung.graphql.error.handling.repository;
+
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface InventoryRepository extends JpaRepository<Vehicle, String>  {
+}
@@ -0,0 +1,9 @@
+package com.baeldung.graphql.error.handling.repository;
+
+import com.baeldung.graphql.error.handling.domain.Location;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface LocationRepository extends JpaRepository<Location, String>  {
+}
@@ -0,0 +1,20 @@
+package com.baeldung.graphql.error.handling.resolver;
+
+import com.baeldung.graphql.error.handling.domain.Location;
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import com.baeldung.graphql.error.handling.service.InventoryService;
+import com.coxautodev.graphql.tools.GraphQLMutationResolver;
+import org.springframework.stereotype.Component;
+
+@Component
+public class Mutation implements GraphQLMutationResolver {
+    private InventoryService inventoryService;
+
+    public Mutation(InventoryService inventoryService) {
+        this.inventoryService = inventoryService;
+    }
+
+    public Vehicle addVehicle(String vin, Integer year, String make, String model, String trim, Location location) {
+        return this.inventoryService.addVehicle(vin, year, make, model, trim, location);
+    }
+}
@@ -0,0 +1,29 @@
+package com.baeldung.graphql.error.handling.resolver;
+
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import com.baeldung.graphql.error.handling.service.InventoryService;
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+
+@Component
+public class Query implements GraphQLQueryResolver  {
+    private final InventoryService inventoryService;
+
+    public Query(InventoryService inventoryService) {
+        this.inventoryService = inventoryService;
+    }
+
+    public List<Vehicle> searchAll() {
+        return this.inventoryService.searchAll();
+    }
+
+    public List<Vehicle> searchByLocation(String zipcode) {
+        return this.inventoryService.searchByLocation(zipcode);
+    }
+
+    public Vehicle searchByVin(String vin) {
+        return this.inventoryService.searchByVin(vin);
+    }
+}
@@ -0,0 +1,67 @@
+package com.baeldung.graphql.error.handling.service;
+
+import com.baeldung.graphql.error.handling.domain.Location;
+import com.baeldung.graphql.error.handling.domain.Vehicle;
+import com.baeldung.graphql.error.handling.exception.InvalidInputException;
+import com.baeldung.graphql.error.handling.exception.VehicleAlreadyPresentException;
+import com.baeldung.graphql.error.handling.exception.VehicleNotFoundException;
+import com.baeldung.graphql.error.handling.repository.InventoryRepository;
+import com.baeldung.graphql.error.handling.repository.LocationRepository;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Service;
+
+import javax.transaction.Transactional;
+import java.util.*;
+
+@Service
+public class InventoryService {
+    private InventoryRepository inventoryRepository;
+    private LocationRepository locationRepository;
+
+    public InventoryService(InventoryRepository inventoryRepository, LocationRepository locationRepository) {
+        this.inventoryRepository = inventoryRepository;
+        this.locationRepository = locationRepository;
+    }
+
+    @Transactional
+    public Vehicle addVehicle(String vin, Integer year, String make, String model, String trim, Location location) {
+        Optional<Vehicle> existingVehicle = this.inventoryRepository.findById(vin);
+        if (existingVehicle.isPresent()) {
+            Map<String, Object> params = new HashMap<>();
+            params.put("vin", vin);
+            throw new VehicleAlreadyPresentException("Failed to add vehicle. Vehicle with vin " + vin + " already present.", params);
+        }
+        Vehicle vehicle = Vehicle.builder()
+                .vin(vin)
+                .year(year)
+                .make(make)
+                .model(model)
+                .location(location)
+                .trim(trim)
+                .build();
+
+        this.locationRepository.save(location);
+        return this.inventoryRepository.save(vehicle);
+    }
+
+    public List<Vehicle> searchAll() {
+        return this.inventoryRepository.findAll();
+    }
+
+    public List<Vehicle> searchByLocation(String zipcode) {
+        if (StringUtils.isEmpty(zipcode) || zipcode.length() != 5) {
+            throw new InvalidInputException("Invalid zipcode " + zipcode + " provided.");
+        }
+        return this.locationRepository.findById(zipcode)
+                .map(Location::getVehicles)
+                .orElse(new ArrayList<>());
+    }
+
+    public Vehicle searchByVin(String vin) {
+        return this.inventoryRepository.findById(vin).orElseThrow(() -> {
+            Map<String, Object> params = new HashMap<>();
+            params.put("vin", vin);
+            return new VehicleNotFoundException("Vehicle with vin " + vin + " not found.", params);
+        });
+    }
+}
@@ -0,0 +1,23 @@
+graphql:
+  servlet:
+    mapping: /graphql
+
+spring:
+  datasource:
+    url: "jdbc:h2:mem:graphqldb"
+    driverClassName: "org.h2.Driver"
+    username: sa
+    password:
+
+    initialization-mode: always
+    platform: h2
+
+  jpa:
+    show-sql: true
+    properties:
+      hibernate:
+        dialect: org.hibernate.dialect.H2Dialect
+        ddl-auto: none
+
+  h2:
+    console.enabled: true
@@ -0,0 +1,23 @@
+type Vehicle {
+  vin: ID!
+  year: Int!
+  make: String!
+  model: String!
+  trim: String!
+}
+
+input Location {
+  city: String
+  state: String
+  zipcode: String!
+}
+
+type Query {
+  searchAll:  [Vehicle]!
+  searchByLocation(zipcode: String!): [Vehicle]!
+  searchByVin(vin: String!): Vehicle
+}
+
+type Mutation {
+  addVehicle(vin: ID!, year: Int!, make: String!, model: String!, trim: String, location: Location): Vehicle!
+}
@@ -0,0 +1,7 @@
+insert into LOCATION values('07092', 'Mountainside', 'NJ');
+insert into LOCATION values ('94118', 'San Francisco', 'CA');
+insert into LOCATION values ('10002', 'New York', 'NY');
+
+insert into VEHICLE (vin, year, make, model, trim, fk_location) values('KM8JN72DX7U587496', 2007, 'Hyundai', 'Tucson', null, '07092');
+insert into VEHICLE (vin, year, make, model, trim, fk_location) values('JTKKU4B41C1023346', 2012, 'Toyota', 'Scion', 'Xd', '94118');
+insert into VEHICLE (vin, year, make, model, trim, fk_location) values('1G1JC1444PZ215071', 2000, 'Chevrolet', 'CAVALIER VL', 'RS', '07092');
@@ -0,0 +1,55 @@
+package com.baeldung.graphql.error.handling;
+
+import com.graphql.spring.boot.test.GraphQLResponse;
+import com.graphql.spring.boot.test.GraphQLTestTemplate;
+import org.json.JSONException;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.skyscreamer.jsonassert.JSONAssert;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import java.io.IOException;
+
+import static com.baeldung.graphql.error.handling.TestUtils.readFile;
+import static java.lang.String.format;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, classes = GraphQLErrorHandlerApplication.class)
+public class GraphQLErrorHandlerApplicationIntegrationTest {
+
+    @Autowired
+    private GraphQLTestTemplate graphQLTestTemplate;
+
+    private static final String GRAPHQL_TEST_REQUEST_PATH = "graphql/request/%s.graphql";
+    private static final String GRAPHQL_TEST_RESPONSE_PATH = "graphql/response/%s.json";
+
+    @Test
+    public void whenUnknownOperation_thenRespondWithRequestError() throws IOException, JSONException {
+        String graphqlName = "request_error_unknown_operation";
+        GraphQLResponse actualResponse = graphQLTestTemplate.postForResource(format(GRAPHQL_TEST_REQUEST_PATH, graphqlName));
+        String expectedResponse = readFile(format(GRAPHQL_TEST_RESPONSE_PATH, graphqlName));
+
+        JSONAssert.assertEquals(expectedResponse, actualResponse.getRawResponse().getBody(), true);
+    }
+
+    @Test
+    public void whenInvalidSyntaxRequest_thenRespondWithRequestError() throws IOException, JSONException {
+        String graphqlName = "request_error_invalid_request_syntax";
+        GraphQLResponse actualResponse = graphQLTestTemplate.postForResource(format(GRAPHQL_TEST_REQUEST_PATH, graphqlName));
+        String expectedResponse = readFile(format(GRAPHQL_TEST_RESPONSE_PATH, graphqlName));
+
+        JSONAssert.assertEquals(expectedResponse, actualResponse.getRawResponse().getBody(), true);
+    }
+
+    @Test
+    public void whenRequestAllNonNullField_thenRespondPartialDataWithFieldError() throws IOException, JSONException {
+        String graphqlName = "field_error_request_non_null_fields_partial_response";
+        GraphQLResponse actualResponse = graphQLTestTemplate.postForResource(format(GRAPHQL_TEST_REQUEST_PATH, graphqlName));
+        String expectedResponse = readFile(format(GRAPHQL_TEST_RESPONSE_PATH, graphqlName));
+
+        JSONAssert.assertEquals(expectedResponse, actualResponse.getRawResponse().getBody(), true);
+    }
+}
@@ -0,0 +1,15 @@
+package com.baeldung.graphql.error.handling;
+
+import org.apache.commons.io.IOUtils;
+import org.springframework.core.io.ClassPathResource;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+
+public class TestUtils {
+    public static String readFile(String path) throws IOException {
+        return IOUtils.toString(
+            new ClassPathResource(path).getInputStream(), Charset.defaultCharset()
+        );
+    }
+}
@@ -0,0 +1,10 @@
+# trim is non null but one of the record has null value for trim
+query {
+    searchAll {
+        vin
+        year
+        make
+        model
+        trim
+    }
+}
@@ -0,0 +1,9 @@
+query {
+    searchByVin(vin: "error) {
+        vin
+        year
+        make
+        model
+        trim
+    }
+}
@@ -0,0 +1,9 @@
+subscription {
+    searchByVin(vin: "75024") {
+        vin
+        year
+        make
+        model
+        trim
+    }
+}
@@ -0,0 +1,34 @@
+{
+    "data": {
+        "searchAll": [
+            null,
+            {
+                "vin": "JTKKU4B41C1023346",
+                "year": 2012,
+                "make": "Toyota",
+                "model": "Scion",
+                "trim": "Xd"
+            },
+            {
+                "vin": "1G1JC1444PZ215071",
+                "year": 2000,
+                "make": "Chevrolet",
+                "model": "CAVALIER VL",
+                "trim": "RS"
+            }
+        ]
+    },
+    "errors": [
+        {
+            "message": "Cannot return null for non-nullable type: 'String' within parent 'Vehicle' (/searchAll[0]/trim)",
+            "path": [
+                "searchAll",
+                0,
+                "trim"
+            ],
+            "errorType": "DataFetchingException",
+            "locations": null,
+            "extensions": null
+        }
+    ]
+}
@@ -0,0 +1,18 @@
+{
+    "data": null,
+    "errors": [
+        {
+            "message": "Invalid Syntax",
+            "locations": [
+                {
+                    "line": 5,
+                    "column": 8,
+                    "sourceName": null
+                }
+            ],
+            "errorType": "InvalidSyntax",
+            "path": null,
+            "extensions": null
+        }
+    ]
+}
@@ -0,0 +1,18 @@
+{
+    "data": null,
+    "errors": [
+        {
+            "errorType": "OperationNotSupported",
+            "locations": [
+                {
+                    "line": 1,
+                    "column": 1,
+                    "sourceName": null
+                }
+            ],
+            "extensions": null,
+            "message": "Schema is not configured for subscriptions.",
+            "path": null
+        }
+    ]
+}
@@ -0,0 +1,9 @@
+## GraphQL Java
+
+This module contains articles about GraphQL with Java
+
+## Relevant articles:
+
+- [Introduction to GraphQL](https://www.baeldung.com/graphql)
+- [Make a Call to a GraphQL Service from a Java Application](https://www.baeldung.com/java-call-graphql-service)
+- [Return Map from GraphQL](https://www.baeldung.com/java-graphql-return-map)
@@ -0,0 +1,8 @@
+{
+  "query": "mutation($name: String! $email: String! $age: String! ){ createUser ( name: $name email: $email age: $age) { id name email age } }",
+  "parameters": {
+    "name": "John",
+	"email": "john@email.com",
+    "age": 34
+  }
+}
@@ -0,0 +1,6 @@
+{
+  "query": "mutation($name: String! ){ deleteUser ( id: $id) { id name email age} }",
+  "parameters": {
+    "id": 2
+  }
+}
@@ -0,0 +1,4 @@
+{
+  "query": "{ listUsers{ id name email age}}",
+  "parameters": {}
+}
@@ -0,0 +1,6 @@
+{
+  "query": "query($id: String!){ retrieveUser ( id: $id) { id name email} }",
+  "parameters": {
+    "id": 1
+  }
+}
@@ -0,0 +1,6 @@
+{
+  "query": "query($id: String!){ searchName ( id: $id) { id name email} }",
+  "parameters": {
+    "id": 2
+  }
+}
@@ -0,0 +1,9 @@
+{
+	"query": "mutation($id: String! $name: String! $email: String! $age: String! ){ updateUser ( id: $id name: $name email: $email age: $age) { id name email age} }",
+	"parameters": {
+		"id": 1,
+		"name":"John updated",
+		"email": "johnupdate@email.com",
+		"age": 50
+	}
+}
@@ -0,0 +1,163 @@
+
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>graphql-java</artifactId>
+    <version>1.0</version>
+    <name>graphql-java</name>
+
+    <parent>
+        <groupId>com.baeldung.graphql</groupId>
+        <artifactId>graphql-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <repositories>
+        <repository>
+            <id>jitpack.io</id>
+            <url>https://jitpack.io</url>
+        </repository>
+        <repository>
+            <snapshots>
+                <enabled>false</enabled>
+            </snapshots>
+            <id>central</id>
+            <name>Central Repository</name>
+            <url>https://repo.maven.apache.org/maven2</url>
+        </repository>
+    </repositories>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-annotations</artifactId>
+            <version>${graphql-java-annotations.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.ratpack</groupId>
+            <artifactId>ratpack-core</artifactId>
+            <version>${ratpack-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.github.americanexpress.nodes</groupId>
+            <artifactId>nodes</artifactId>
+            <version>${nodes.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java</artifactId>
+            <version>${graphql-java.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-tools</artifactId>
+            <version>${graphql-java-tools.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-servlet</artifactId>
+            <version>${graphql-java-servlet.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java-generator</groupId>
+            <artifactId>graphql-java-runtime</artifactId>
+            <version>${graphql.java.generator.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>javax.servlet-api</artifactId>
+            <version>${javax.servlet-api.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpclient</artifactId>
+            <version>${httpclient.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.mock-server</groupId>
+            <artifactId>mockserver-netty</artifactId>
+            <version>${mockserver-netty.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mock-server</groupId>
+            <artifactId>mockserver-client-java</artifactId>
+            <version>${mockserver-client-java.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-extended-scalars</artifactId>
+            <version>${graphql-java-extended-scalars.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.eclipse.jetty</groupId>
+                <artifactId>jetty-maven-plugin</artifactId>
+                <version>${jetty-maven-plugin.version}</version>
+            </plugin>
+            <plugin>
+                <artifactId>maven-war-plugin</artifactId>
+                <version>${maven-war-plugin.version}</version>
+            </plugin>
+            <plugin>
+                <groupId>com.graphql-java-generator</groupId>
+                <artifactId>graphql-maven-plugin</artifactId>
+                <version>${graphql.java.generator.version}</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>generateClientCode</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <packageName>com.baeldung.graphql.generated</packageName>
+                    <copyRuntimeSources>false</copyRuntimeSources>
+                    <generateDeprecatedRequestResponse>false</generateDeprecatedRequestResponse>
+                    <separateUtilityClasses>true</separateUtilityClasses>
+                    <customScalars>
+                        <customScalar>
+                            <graphQLTypeName>JSON</graphQLTypeName>
+                            <javaType>java.util.Map</javaType>
+                            <graphQLScalarTypeClass>com.baeldung.graphqlreturnmap.ExtendedGraphQLScalarType</graphQLScalarTypeClass>
+                        </customScalar>
+                    </customScalars>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <graphql-java.version>11.0</graphql-java.version>
+        <graphql-java-tools.version>5.2.4</graphql-java-tools.version>
+        <graphql-java-servlet.version>6.1.3</graphql-java-servlet.version>
+        <graphql-java-annotations.version>3.0.3</graphql-java-annotations.version>
+        <graphql.java.generator.version>1.18</graphql.java.generator.version>
+        <ratpack-core.version>1.9.0</ratpack-core.version>
+        <nodes.version>0.5.0</nodes.version>
+        <httpclient.version>4.5.13</httpclient.version>
+        <mockserver-netty.version>5.13.2</mockserver-netty.version>
+        <mockserver-client-java.version>5.13.2</mockserver-client-java.version>
+        <jetty-maven-plugin.version>10.0.7</jetty-maven-plugin.version>
+        <graphql.java.generator.version>1.18</graphql.java.generator.version>
+        <graphql-java-extended-scalars.version>2022-04-06T00-10-27-a70541e</graphql-java-extended-scalars.version>
+    </properties>
+
+</project>
@@ -0,0 +1,17 @@
+package com.baeldung.graphql;
+
+import ratpack.server.RatpackServer;
+
+import com.baeldung.graphql.handler.UserHandler;
+
+public class Application {
+    public static void main(String[] args) throws Exception {
+        new Application();
+    }
+
+    private Application() throws Exception {
+        final RatpackServer server = RatpackServer.of(s -> s.handlers(chain -> chain.post("users", new UserHandler())));
+        server.start();
+    }
+
+}
@@ -0,0 +1,24 @@
+package com.baeldung.graphql.clients;
+
+import com.baeldung.graphql.data.Data;
+import io.aexp.nodes.graphql.GraphQLRequestEntity;
+import io.aexp.nodes.graphql.GraphQLResponseEntity;
+import io.aexp.nodes.graphql.GraphQLTemplate;
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.IOException;
+
+public class AmericanExpressNodes {
+
+    public static GraphQLResponseEntity<Data> callGraphQLService(String url, String query) throws IOException {
+        GraphQLTemplate graphQLTemplate = new GraphQLTemplate();
+
+        GraphQLRequestEntity requestEntity = GraphQLRequestEntity.Builder()
+          .url(StringUtils.join(url, "?query=", query))
+          .request(Data.class)
+          .build();
+
+        return graphQLTemplate.query(requestEntity, Data.class);
+    }
+
+}
@@ -0,0 +1,25 @@
+package com.baeldung.graphql.clients;
+
+import org.apache.http.HttpResponse;
+import org.apache.http.client.HttpClient;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.client.utils.URIBuilder;
+import org.apache.http.impl.client.HttpClientBuilder;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+
+public class ApacheHttpClient {
+
+    public static HttpResponse callGraphQLService(String url, String query) throws URISyntaxException, IOException {
+        HttpClient client = HttpClientBuilder.create().build();
+        HttpGet request = new HttpGet(url);
+        URI uri = new URIBuilder(request.getURI())
+          .addParameter("query", query)
+          .build();
+        request.setURI(uri);
+        return client.execute(request);
+    }
+
+}
@@ -0,0 +1,31 @@
+package com.baeldung.graphql.data;
+
+import org.apache.commons.lang3.StringUtils;
+
+public class Author {
+
+    private String name;
+    private String surname;
+
+    public Author() {
+
+    }
+
+    public Author(String name, String surname) {
+        this.name = name;
+        this.surname = surname;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getSurname() {
+        return surname;
+    }
+
+    public String getFullName() {
+        return StringUtils.join(getName(), " ", getSurname());
+    }
+
+}
@@ -0,0 +1,25 @@
+package com.baeldung.graphql.data;
+
+public class Book {
+
+    private String title;
+    private Author author;
+
+    public Book() {
+
+    }
+
+    public Book(String title, Author author) {
+        this.title = title;
+        this.author = author;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public Author getAuthor() {
+        return author;
+    }
+
+}
@@ -0,0 +1,19 @@
+package com.baeldung.graphql.data;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class BookRepository {
+
+    private static final List<Book> books = Stream.of(
+            new Book("Title 1", new Author("Pero", "Peric")),
+            new Book("Title 2", new Author("Marko", "Maric"))
+        ).collect(Collectors.toList());
+
+    public List<Book> getAllBooks() {
+        return Collections.unmodifiableList(books);
+    }
+
+}
@@ -0,0 +1,22 @@
+package com.baeldung.graphql.data;
+
+import java.util.Collections;
+import java.util.List;
+
+public class Data {
+
+    private List<Book> allBooks;
+
+    public Data() {
+
+    }
+
+    public Data(List<Book> allBooks) {
+        this.allBooks = allBooks;
+    }
+
+    public List<Book> getAllBooks() {
+        return Collections.unmodifiableList(allBooks);
+    }
+
+}
@@ -0,0 +1,19 @@
+package com.baeldung.graphql.data;
+
+public class Response {
+
+    private Data data;
+
+    public Response() {
+
+    }
+
+    public Response(Data data) {
+        this.data = data;
+    }
+
+    public Data getData() {
+        return data;
+    }
+
+}
@@ -0,0 +1,78 @@
+package com.baeldung.graphql.entity;
+
+import java.util.List;
+
+import com.baeldung.graphql.handler.UserHandler;
+import com.baeldung.graphql.utils.SchemaUtils;
+
+import graphql.annotations.GraphQLField;
+import graphql.annotations.GraphQLName;
+
+@GraphQLName(SchemaUtils.USER)
+public class User {
+
+    @GraphQLField
+    private Long id;
+    @GraphQLField
+    private String name;
+    @GraphQLField
+    private String email;
+    @GraphQLField
+    private Integer age;
+
+    public User(String name, String email, Integer age) {
+        this.id = genId();
+        this.name = name;
+        this.email = email;
+        this.age = age;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+
+    public static Long genId() {
+        Long id = 1L;
+        try {
+            List<User> users =  new UserHandler().getUsers();
+            for (User user : users)
+                id = (user.getId() > id ? user.getId() : id) + 1;
+           
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return id;
+    }
+    
+    public String toString() {
+        return "[id=" + id + ", name=" + name + ", email="+email+ ", age="+ age +"]";
+    }
+}
@@ -0,0 +1,59 @@
+package com.baeldung.graphql.handler;
+
+import graphql.ExecutionResult;
+import graphql.GraphQL;
+import graphql.schema.DataFetchingEnvironment;
+import ratpack.handling.Context;
+import ratpack.handling.Handler;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.logging.Logger;
+
+import com.baeldung.graphql.entity.User;
+import com.baeldung.graphql.schema.UserSchema;
+import com.baeldung.graphql.utils.SchemaUtils;
+
+import static ratpack.jackson.Jackson.json;
+
+public class UserHandler implements Handler {
+
+    private static final Logger LOGGER = Logger.getLogger(UserHandler.class.getSimpleName());
+
+    private static final List<User> USERS = new ArrayList<>();
+
+    private final GraphQL graphql;
+
+    public UserHandler() throws Exception {
+        graphql = GraphQL.newGraphQL(new UserSchema().getSchema()).build();
+    }
+
+    @Override
+    public void handle(Context context) {
+        context.parse(Map.class)
+            .then(payload -> {
+                Map<String, Object> parameters = (Map<String, Object>) payload.get("parameters");
+                ExecutionResult executionResult = graphql.execute(payload.get(SchemaUtils.QUERY)
+                    .toString(), null, this, parameters);
+
+                Map<String, Object> result = new LinkedHashMap<>();
+                if (executionResult.getErrors().isEmpty()) {
+                    result.put(SchemaUtils.DATA, executionResult.getData());
+                } else {
+                    result.put(SchemaUtils.ERRORS, executionResult.getErrors());
+                    LOGGER.warning("Errors: " + executionResult.getErrors());
+                }
+                context.render(json(result));
+            });
+    }
+
+    public List<User> getUsers() {
+        return USERS;
+    }
+
+    public static List<User> getUsers(DataFetchingEnvironment env) {
+        return ((UserHandler) env.getSource()).getUsers();
+    }
+}
@@ -0,0 +1,57 @@
+package com.baeldung.graphql.mutation;
+
+import graphql.annotations.GraphQLField;
+import graphql.annotations.GraphQLName;
+import graphql.schema.DataFetchingEnvironment;
+
+import javax.validation.constraints.NotNull;
+
+import com.baeldung.graphql.entity.User;
+import com.baeldung.graphql.utils.SchemaUtils;
+
+import java.util.List;
+import java.util.Optional;
+
+import static com.baeldung.graphql.handler.UserHandler.getUsers;
+
+@GraphQLName(SchemaUtils.MUTATION)
+public class UserMutation {
+    @GraphQLField
+    public static User createUser(final DataFetchingEnvironment env, @NotNull @GraphQLName(SchemaUtils.NAME) final String name, @NotNull @GraphQLName(SchemaUtils.EMAIL) final String email, @NotNull @GraphQLName(SchemaUtils.AGE) final String age) {
+        List<User> users = getUsers(env);
+        final User user = new User(name, email, Integer.valueOf(age));
+        users.add(user);
+        return user;
+    }
+
+    @GraphQLField
+    public static User updateUser(final DataFetchingEnvironment env, @NotNull @GraphQLName(SchemaUtils.ID) final String id, @NotNull @GraphQLName(SchemaUtils.NAME) final String name, @NotNull @GraphQLName(SchemaUtils.EMAIL) final String email,
+        @NotNull @GraphQLName(SchemaUtils.AGE) final String age) {
+        final Optional<User> user = getUsers(env).stream()
+            .filter(c -> c.getId() == Long.parseLong(id))
+            .findFirst();
+        if (!user.isPresent()) {
+            return null;
+        }
+        user.get()
+            .setName(name);
+        user.get()
+            .setEmail(email);
+        user.get()
+            .setAge(Integer.valueOf(age));
+        return user.get();
+    }
+
+    @GraphQLField
+    public static User deleteUser(final DataFetchingEnvironment env, @NotNull @GraphQLName(SchemaUtils.ID) final String id) {
+        final List<User> users = getUsers(env);
+        final Optional<User> user = users.stream()
+            .filter(c -> c.getId() == Long.parseLong(id))
+            .findFirst();
+        if (!user.isPresent()) {
+            return null;
+        }
+        users.removeIf(c -> c.getId() == Long.parseLong(id));
+        return user.get();
+    }
+}
@@ -0,0 +1,42 @@
+package com.baeldung.graphql.query;
+
+import graphql.annotations.GraphQLField;
+import graphql.annotations.GraphQLName;
+import graphql.schema.DataFetchingEnvironment;
+
+import javax.validation.constraints.NotNull;
+
+import com.baeldung.graphql.entity.User;
+import com.baeldung.graphql.utils.SchemaUtils;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import static com.baeldung.graphql.handler.UserHandler.getUsers;
+
+@GraphQLName(SchemaUtils.QUERY)
+public class UserQuery {
+
+    @GraphQLField
+    public static User retrieveUser(final DataFetchingEnvironment env, @NotNull @GraphQLName(SchemaUtils.ID) final String id) {
+        final Optional<User> any = getUsers(env).stream()
+            .filter(c -> c.getId() == Long.parseLong(id))
+            .findFirst();
+        return any.orElse(null);
+    }
+    
+    @GraphQLField
+    public static List<User> searchName(final DataFetchingEnvironment env, @NotNull @GraphQLName(SchemaUtils.NAME) final String name) {
+        return getUsers(env).stream()
+            .filter(c -> c.getName()
+                .contains(name))
+            .collect(Collectors.toList());
+    }
+    
+    @GraphQLField
+    public static List<User> listUsers(final DataFetchingEnvironment env) {
+        return getUsers(env);
+    }
+
+}
@@ -0,0 +1,24 @@
+package com.baeldung.graphql.schema;
+
+import graphql.annotations.GraphQLAnnotations;
+import graphql.schema.GraphQLSchema;
+
+import static graphql.schema.GraphQLSchema.newSchema;
+
+import com.baeldung.graphql.mutation.UserMutation;
+import com.baeldung.graphql.query.UserQuery;
+
+public class UserSchema {
+
+    private final GraphQLSchema schema;
+
+    public UserSchema() throws IllegalAccessException, NoSuchMethodException, InstantiationException {
+        schema = newSchema().query(GraphQLAnnotations.object(UserQuery.class))
+            .mutation(GraphQLAnnotations.object(UserMutation.class))
+            .build();
+    }
+
+    public GraphQLSchema getSchema() {
+        return schema;
+    }
+}
@@ -0,0 +1,36 @@
+package com.baeldung.graphql.server;
+
+import com.baeldung.graphql.data.BookRepository;
+import com.coxautodev.graphql.tools.SchemaParser;
+import graphql.schema.GraphQLSchema;
+import graphql.servlet.SimpleGraphQLHttpServlet;
+
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+@WebServlet(urlPatterns = "/graphql")
+public class GraphQLEndpoint extends HttpServlet {
+
+    private SimpleGraphQLHttpServlet graphQLServlet;
+
+    @Override
+    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        graphQLServlet.service(req, resp);
+    }
+
+    @Override
+    public void init() {
+        GraphQLSchema schema = SchemaParser.newParser()
+          .resolvers(new GraphQLQuery(new BookRepository()))
+          .file("schema.graphqls")
+          .build()
+          .makeExecutableSchema();
+        graphQLServlet = SimpleGraphQLHttpServlet
+          .newBuilder(schema)
+          .build();
+    }
+}
@@ -0,0 +1,30 @@
+package com.baeldung.graphql.server;
+
+import com.baeldung.graphql.data.Book;
+import com.baeldung.graphql.data.BookRepository;
+import com.baeldung.graphqlreturnmap.entity.Product;
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+
+import java.util.List;
+
+public class GraphQLQuery implements GraphQLQueryResolver {
+
+    private final BookRepository repository;
+
+    public GraphQLQuery(BookRepository repository) {
+        this.repository = repository;
+    }
+
+    public List<Book> allBooks() {
+        return repository.getAllBooks();
+    }
+
+    public List<Product> getProducts(int pageSize, int pageNumber) {
+        return null;
+    }
+
+    public Product getProduct(int id) {
+        return null;
+    }
+
+}
@@ -0,0 +1,14 @@
+package com.baeldung.graphql.utils;
+
+public class SchemaUtils {
+    public static final String USER = "user";
+    public static final String ID = "id";
+    public static final String NAME = "name";
+    public static final String EMAIL = "email";
+    public static final String AGE = "age";
+    
+    public static final String MUTATION = "mutation";
+    public static final String QUERY = "query";
+    public static final String ERRORS = "errors";
+    public static final String DATA = "data";
+}
@@ -0,0 +1,52 @@
+package com.baeldung.graphqlreturnmap;
+
+import com.baeldung.graphql.utils.SchemaUtils;
+import com.baeldung.graphqlreturnmap.resolver.ProductResolver;
+import com.baeldung.graphqlreturnmap.resolver.Query;
+import com.coxautodev.graphql.tools.SchemaParser;
+import graphql.ExecutionResult;
+import graphql.GraphQL;
+import graphql.scalars.ExtendedScalars;
+import graphql.schema.GraphQLSchema;
+import ratpack.handling.Context;
+import ratpack.handling.Handler;
+
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.logging.Logger;
+
+import static ratpack.jackson.Jackson.json;
+
+public class AppHandler implements Handler {
+    private static final Logger LOGGER = Logger.getLogger(AppHandler.class.getSimpleName());
+    private GraphQL graphql;
+
+    public AppHandler() throws Exception {
+        GraphQLSchema schema = SchemaParser.newParser()
+            .resolvers(new Query(), new ProductResolver())
+            .scalars(ExtendedScalars.Json)
+            .file("schema.graphqls")
+            .build()
+            .makeExecutableSchema();
+        graphql = GraphQL.newGraphQL(schema).build();
+    }
+
+    @Override
+    public void handle(Context context) throws Exception {
+        context.parse(Map.class)
+            .then(payload -> {
+                ExecutionResult executionResult = graphql.execute(payload.get(SchemaUtils.QUERY)
+                    .toString(), null, this, Collections.emptyMap());
+                Map<String, Object> result = new LinkedHashMap<>();
+                if (executionResult.getErrors()
+                    .isEmpty()) {
+                    result.put(SchemaUtils.DATA, executionResult.getData());
+                } else {
+                    result.put(SchemaUtils.ERRORS, executionResult.getErrors());
+                    LOGGER.warning("Errors: " + executionResult.getErrors());
+                }
+                context.render(json(result));
+            });
+    }
+}
@@ -0,0 +1,24 @@
+package com.baeldung.graphqlreturnmap;
+
+import graphql.language.ScalarTypeDefinition;
+import graphql.schema.Coercing;
+import graphql.schema.GraphQLDirective;
+import graphql.schema.GraphQLScalarType;
+
+import java.util.List;
+
+public class ExtendedGraphQLScalarType extends GraphQLScalarType {
+
+    public ExtendedGraphQLScalarType(){
+        super("","",null);
+
+    }
+
+    public ExtendedGraphQLScalarType(String name, String description, Coercing coercing) {
+        super(name, description, coercing);
+    }
+
+    public ExtendedGraphQLScalarType(String name, String description, Coercing coercing, List<GraphQLDirective> directives, ScalarTypeDefinition definition) {
+        super(name, description, coercing, directives, definition);
+    }
+}
@@ -0,0 +1,12 @@
+package com.baeldung.graphqlreturnmap;
+
+import ratpack.server.RatpackServer;
+
+public class GraphqlReturnMap {
+
+    public static void main(String[] args) throws Exception {
+        final RatpackServer server = RatpackServer.of(s -> s.handlers(chain -> chain.post("product", new AppHandler())));
+        server.start();
+    }
+
+}
@@ -0,0 +1,46 @@
+package com.baeldung.graphqlreturnmap.entity;
+
+public class Attribute {
+    private String name;
+    private String description;
+    private String unit;
+
+    public Attribute(String name, String description, String unit){
+        this.name = name;
+        this.description = description;
+        this.unit = unit;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public String getUnit() {
+        return unit;
+    }
+
+    public void setUnit(String unit) {
+        this.unit = unit;
+    }
+
+    @Override
+    public String toString() {
+        return "Attribute{" +
+                "name='" + name + '\'' +
+                ", description='" + description + '\'' +
+                ", unit='" + unit + '\'' +
+                '}';
+    }
+}
@@ -0,0 +1,48 @@
+package com.baeldung.graphqlreturnmap.entity;
+
+
+import java.util.Map;
+
+public class Product {
+    private Integer id;
+    private String name;
+    private String description;
+    private Map<String, Attribute> attributes;
+
+
+    public Product(){
+
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public Map<String, Attribute> getAttributes() {
+        return attributes;
+    }
+
+    public void setAttributes(Map<String, Attribute> attributes) {
+        this.attributes = attributes;
+    }
+}
@@ -0,0 +1,30 @@
+package com.baeldung.graphqlreturnmap.model;
+
+
+import com.baeldung.graphqlreturnmap.entity.Attribute;
+
+public class AttributeKeyValueModel {
+    private String key;
+    private Attribute value;
+
+    public AttributeKeyValueModel(String key, Attribute value) {
+        this.key = key;
+        this.value = value;
+    }
+
+    public String getKey() {
+        return key;
+    }
+
+    public void setKey(String key) {
+        this.key = key;
+    }
+
+    public Attribute getValue() {
+        return value;
+    }
+
+    public void setValue(Attribute value) {
+        this.value = value;
+    }
+}
@@ -0,0 +1,12 @@
+package com.baeldung.graphqlreturnmap.repository;
+
+
+import com.baeldung.graphqlreturnmap.entity.Product;
+
+import java.util.List;
+
+public interface ProductRepository {
+    List<Product> getProducts(Integer pageSize, Integer pageNumber);
+    Product getProduct(Integer id);
+
+}
@@ -0,0 +1,43 @@
+package com.baeldung.graphqlreturnmap.repository.impl;
+
+import com.baeldung.graphqlreturnmap.entity.Attribute;
+import com.baeldung.graphqlreturnmap.entity.Product;
+import com.baeldung.graphqlreturnmap.repository.ProductRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+@Repository
+public class ProductRepositoryImpl implements ProductRepository {
+
+    private static List<Product> productList = new ArrayList<>();
+
+    public ProductRepositoryImpl() {
+        for (int i = 1; i <= 10; i++){
+            Product product = new Product();
+            product.setId(i);
+            product.setName(String.format("Product %d", i));
+            product.setDescription(String.format("Product %d description", i));
+            product.setAttributes(createAttributes(i));
+            productList.add(product);
+        }
+    }
+
+    private Map<String, Attribute> createAttributes(int i) {
+        Map<String, Attribute> attributeMap = new HashMap<>();
+        attributeMap.put(String.format("attribute_%d",i), new Attribute(String.format("Attribute%d name",i),"This is custom attribute description","This is custom attribute unit"));
+        attributeMap.put("size", new Attribute((i & 1) == 0 ? "Small" : "Large","This is custom attribute description","This is custom attribute unit"));
+        return attributeMap;
+    }
+
+    @Override
+    public List<Product> getProducts(Integer pageSize, Integer pageNumber) {
+        return productList.stream().skip(pageSize*pageNumber).limit(pageSize).collect(Collectors.toList());
+    }
+
+    @Override
+    public Product getProduct(Integer id) {
+        return productList.stream().filter(product -> product.getId().equals(id)).findFirst().orElse(null);
+    }
+}
@@ -0,0 +1,30 @@
+package com.baeldung.graphqlreturnmap.resolver;
+
+import com.baeldung.graphqlreturnmap.entity.Product;
+import com.baeldung.graphqlreturnmap.model.AttributeKeyValueModel;
+import com.coxautodev.graphql.tools.GraphQLResolver;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class ProductResolver implements GraphQLResolver<Product> {
+    public ProductResolver(){
+    }
+
+    public List<AttributeKeyValueModel> getAttribute_list(Product product){
+        List<AttributeKeyValueModel> attributeModelList = new LinkedList<>();
+        product.getAttributes().forEach((key, val) -> attributeModelList.add(new AttributeKeyValueModel(key, val)));
+        return attributeModelList;
+    }
+
+    public String getAttribute_string(Product product){
+        try {
+            return new ObjectMapper().writeValueAsString(product.getAttributes());
+        } catch (JsonProcessingException e) {
+            e.printStackTrace();
+            return "";
+        }
+    }
+}
@@ -0,0 +1,33 @@
+package com.baeldung.graphqlreturnmap.resolver;
+
+import com.baeldung.graphql.data.Book;
+import com.baeldung.graphqlreturnmap.entity.Product;
+import com.baeldung.graphqlreturnmap.repository.ProductRepository;
+import com.baeldung.graphqlreturnmap.repository.impl.ProductRepositoryImpl;
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import java.util.List;
+
+public class Query implements GraphQLQueryResolver {
+
+    @Autowired
+    private ProductRepository productRepository;
+    public Query(){
+        productRepository = new ProductRepositoryImpl();
+    }
+
+    public List<Product> getProducts(int pageSize, int pageNumber) {
+        return productRepository.getProducts(pageSize, pageNumber);
+    }
+
+    public Product getProduct(int id) {
+        return productRepository.getProduct(id);
+    }
+
+    public List<Book> allBooks() {
+        return null;
+    }
+
+
+}
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>
@@ -0,0 +1,43 @@
+type Book {
+  title: String!
+  author: Author
+}
+
+type Author {
+  name: String!
+  surname: String!
+}
+
+type Query {
+  allBooks: [Book]
+  products(size: Int, page: Int): [Product]!
+  product(id: Int): Product!
+}
+
+
+
+type Product {
+  id: ID
+  name: String!
+  description: String
+  attribute_string:String
+  attribute_list:[AttributeKeyValuePair]
+  attributes: JSON
+}
+
+type AttributeKeyValuePair {
+  key:String
+  value:Attribute
+}
+
+type Attribute {
+  name:String
+  description:String
+  unit:String
+}
+scalar JSON
+
+
+schema {
+  query: Query
+}
@@ -0,0 +1,88 @@
+package com.baeldung.graphql;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.mockserver.client.MockServerClient;
+import org.mockserver.configuration.Configuration;
+import org.mockserver.integration.ClientAndServer;
+import org.mockserver.model.HttpStatusCode;
+import org.slf4j.event.Level;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+
+import static org.mockserver.integration.ClientAndServer.startClientAndServer;
+import static org.mockserver.matchers.Times.exactly;
+import static org.mockserver.model.HttpRequest.request;
+import static org.mockserver.model.HttpResponse.response;
+
+public class GraphQLMockServer {
+
+    private static final String SERVER_ADDRESS = "127.0.0.1";
+    private static final String PATH = "/graphql";
+
+    public static String serviceUrl;
+
+    private static ClientAndServer mockServer;
+    private static int serverPort;
+
+    @BeforeAll
+    static void startServer() throws IOException {
+        serverPort = getFreePort();
+        serviceUrl = "http://" + SERVER_ADDRESS + ":" + serverPort + PATH;
+
+        Configuration config = Configuration.configuration().logLevel(Level.WARN);
+        mockServer = startClientAndServer(config, serverPort);
+
+        mockAllBooksTitleRequest();
+        mockAllBooksTitleAuthorRequest();
+    }
+
+    @AfterAll
+    static void stopServer() {
+        mockServer.stop();
+    }
+
+    private static void mockAllBooksTitleAuthorRequest() {
+        String requestQuery = "{allBooks{title,author{name,surname}}}";
+        String responseJson = "{\"data\":{\"allBooks\":[{\"title\":\"Title 1\",\"author\":{\"name\":\"Pero\",\"surname\":\"Peric\"}},{\"title\":\"Title 2\",\"author\":{\"name\":\"Marko\",\"surname\":\"Maric\"}}]}}";
+
+        new MockServerClient(SERVER_ADDRESS, serverPort)
+          .when(
+            request()
+              .withPath(PATH)
+              .withQueryStringParameter("query", requestQuery),
+            exactly(1)
+          )
+          .respond(
+            response()
+              .withStatusCode(HttpStatusCode.OK_200.code())
+              .withBody(responseJson)
+          );
+    }
+
+    private static void mockAllBooksTitleRequest() {
+        String requestQuery = "{allBooks{title}}";
+        String responseJson = "{\"data\":{\"allBooks\":[{\"title\":\"Title 1\"},{\"title\":\"Title 2\"}]}}";
+
+        new MockServerClient(SERVER_ADDRESS, serverPort)
+          .when(
+            request()
+              .withPath(PATH)
+              .withQueryStringParameter("query", requestQuery),
+            exactly(1)
+          )
+          .respond(
+            response()
+              .withStatusCode(HttpStatusCode.OK_200.code())
+              .withBody(responseJson)
+          );
+    }
+
+    private static int getFreePort () throws IOException {
+        try (ServerSocket serverSocket = new ServerSocket(0)) {
+            return serverSocket.getLocalPort();
+        }
+    }
+
+}
@@ -0,0 +1,39 @@
+package com.baeldung.graphql.clients;
+
+import com.baeldung.graphql.GraphQLMockServer;
+import com.baeldung.graphql.data.Data;
+import io.aexp.nodes.graphql.GraphQLResponseEntity;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertAll;
+
+class AmericanExpressNodesUnitTest extends GraphQLMockServer {
+
+    @Test
+    void givenGraphQLEndpoint_whenRequestingAllBooksWithTitle_thenExpectedJsonIsReturned() throws IOException {
+        GraphQLResponseEntity<Data> responseEntity = AmericanExpressNodes.callGraphQLService(serviceUrl, "{allBooks{title}}");
+
+        assertAll(
+          () -> assertThat(responseEntity.getResponse().getAllBooks()).hasSize(2),
+          () -> assertThat(responseEntity.getResponse().getAllBooks().get(0).getTitle()).isEqualTo("Title 1"),
+          () -> assertThat(responseEntity.getResponse().getAllBooks().get(1).getTitle()).isEqualTo("Title 2")
+        );
+    }
+
+    @Test
+    void givenGraphQLEndpoint_whenRequestingAllBooksWithTitleAndAuthor_thenExpectedJsonIsReturned() throws IOException {
+        GraphQLResponseEntity<Data> responseEntity = AmericanExpressNodes.callGraphQLService(serviceUrl, "{allBooks{title,author{name,surname}}}");
+
+        assertAll(
+          () -> assertThat(responseEntity.getResponse().getAllBooks()).hasSize(2),
+          () -> assertThat(responseEntity.getResponse().getAllBooks().get(0).getTitle()).isEqualTo("Title 1"),
+          () -> assertThat(responseEntity.getResponse().getAllBooks().get(0).getAuthor().getFullName()).isEqualTo("Pero Peric"),
+          () -> assertThat(responseEntity.getResponse().getAllBooks().get(1).getTitle()).isEqualTo("Title 2"),
+          () -> assertThat(responseEntity.getResponse().getAllBooks().get(1).getAuthor().getFullName()).isEqualTo("Marko Maric")
+        );
+    }
+
+}
@@ -0,0 +1,49 @@
+package com.baeldung.graphql.clients;
+
+import com.baeldung.graphql.GraphQLMockServer;
+import com.baeldung.graphql.data.Response;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.commons.io.IOUtils;
+import org.apache.http.HttpResponse;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.nio.charset.StandardCharsets;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertAll;
+
+class ApacheHttpClientUnitTest extends GraphQLMockServer {
+
+    private static final ObjectMapper objectMapper = new ObjectMapper();
+
+    @Test
+    void givenGraphQLEndpoint_whenRequestingAllBooksWithTitle_thenExpectedJsonIsReturned() throws IOException, URISyntaxException {
+        HttpResponse httpResponse = ApacheHttpClient.callGraphQLService(serviceUrl, "{allBooks{title}}");
+        String actualResponse = IOUtils.toString(httpResponse.getEntity().getContent(), StandardCharsets.UTF_8.name());
+        Response parsedResponse = objectMapper.readValue(actualResponse, Response.class);
+
+        assertAll(
+            () -> assertThat(parsedResponse.getData().getAllBooks()).hasSize(2),
+            () -> assertThat(parsedResponse.getData().getAllBooks().get(0).getTitle()).isEqualTo("Title 1"),
+            () -> assertThat(parsedResponse.getData().getAllBooks().get(1).getTitle()).isEqualTo("Title 2")
+        );
+    }
+
+    @Test
+    void givenGraphQLEndpoint_whenRequestingAllBooksWithTitleAndAuthor_thenExpectedJsonIsReturned() throws IOException, URISyntaxException {
+        HttpResponse httpResponse = ApacheHttpClient.callGraphQLService(serviceUrl, "{allBooks{title,author{name,surname}}}");
+        String actualResponse = IOUtils.toString(httpResponse.getEntity().getContent(), StandardCharsets.UTF_8.name());
+        Response parsedResponse = objectMapper.readValue(actualResponse, Response.class);
+
+        assertAll(
+          () -> assertThat(parsedResponse.getData().getAllBooks()).hasSize(2),
+          () -> assertThat(parsedResponse.getData().getAllBooks().get(0).getTitle()).isEqualTo("Title 1"),
+          () -> assertThat(parsedResponse.getData().getAllBooks().get(0).getAuthor().getFullName()).isEqualTo("Pero Peric"),
+          () -> assertThat(parsedResponse.getData().getAllBooks().get(1).getTitle()).isEqualTo("Title 2"),
+          () -> assertThat(parsedResponse.getData().getAllBooks().get(1).getAuthor().getFullName()).isEqualTo("Marko Maric")
+        );
+    }
+
+}
@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Getting Started With GraphQL SPQR and Spring Boot](https://www.baeldung.com/spring-boot-graphql-spqr)
@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>graphql-spqr</artifactId>
+    <version>1.0</version>
+    <name>graphql-spqr</name>
+
+    <parent>
+        <groupId>com.baeldung.graphql</groupId>
+        <artifactId>graphql-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.leangen.graphql</groupId>
+            <artifactId>graphql-spqr-spring-boot-starter</artifactId>
+            <version>${graphql-spqr-spring-boot-starter-version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <graphql-spqr-spring-boot-starter-version>0.0.6</graphql-spqr-spring-boot-starter-version>
+    </properties>
+
+</project>
@@ -0,0 +1,11 @@
+package com.baeldung;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SpringBootApp {
+    public static void main(String[] args) {
+        SpringApplication.run(SpringBootApp.class, args);
+    }
+}
@@ -0,0 +1,57 @@
+package com.baeldung.spqr;
+
+import java.util.Objects;
+
+public class Book {
+    private Integer id;
+    private String author;
+    private String title;
+
+    public Book(Integer id, String author, String title) {
+        this.id = id;
+        this.author = author;
+        this.title = title;
+    }
+
+    public Book() {
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Book book = (Book) o;
+        return id.equals(book.id);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id);
+    }
+}
@@ -0,0 +1,51 @@
+package com.baeldung.spqr;
+
+import io.leangen.graphql.annotations.GraphQLArgument;
+import io.leangen.graphql.annotations.GraphQLMutation;
+import io.leangen.graphql.annotations.GraphQLQuery;
+import io.leangen.graphql.spqr.spring.annotations.GraphQLApi;
+import org.springframework.stereotype.Service;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+@Service
+@GraphQLApi
+public class BookService implements IBookService {
+
+    Set<Book> books = new HashSet<>();
+
+    @GraphQLQuery(name = "getBookWithTitle")
+    public Book getBookWithTitle(@GraphQLArgument(name = "title") String title) {
+        return books.stream()
+            .filter(book -> book.getTitle()
+                .equals(title))
+            .findFirst()
+            .orElse(null);
+    }
+
+    @GraphQLQuery(name = "getAllBooks", description = "Get all books")
+    public List<Book> getAllBooks() {
+        return books.stream().collect(Collectors.toList());
+    }
+
+    @GraphQLMutation(name = "addBook")
+    public Book addBook(@GraphQLArgument(name = "newBook") Book book) {
+        books.add(book);
+        return book;
+    }
+
+    @GraphQLMutation(name = "updateBook")
+    public Book updateBook(@GraphQLArgument(name = "modifiedBook") Book book) {
+        books.remove(book);
+        books.add(book);
+        return book;
+    }
+
+    @GraphQLMutation(name = "deleteBook")
+    public boolean deleteBook(@GraphQLArgument(name = "book") Book book) {
+        return books.remove(book);
+    }
+}
@@ -0,0 +1,15 @@
+package com.baeldung.spqr;
+
+import java.util.List;
+
+public interface IBookService {
+    Book getBookWithTitle(String title);
+
+    List<Book> getAllBooks();
+
+    Book addBook(Book book);
+
+    Book updateBook(Book book);
+
+    boolean deleteBook(Book book);
+}
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.graphql</groupId>
+    <artifactId>graphql-modules</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <name>graphql-modules</name>
+    <packaging>pom</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-boot-2</relativePath>
+    </parent>
+
+    <modules>
+        <module>graphql-dgs</module>
+        <module>graphql-error-handling</module>
+        <module>graphql-java</module>
+        <module>graphql-spqr</module>
+    </modules>
+
+</project>