BAEL-203: Querying Couchbase with MapReduce Views

2017-01-30 21:48:28 -06:00
parent 99e75746f3
commit e371bb9093
9 changed files with 492 additions and 0 deletions
@@ -0,0 +1,6 @@
+package com.baeldung.couchbase.mapreduce;
+
+public interface CouchbaseKeyGenerator<T> {
+
+    String generateKey(T t);
+}
@@ -0,0 +1,10 @@
+package com.baeldung.couchbase.mapreduce;
+
+@SuppressWarnings("serial")
+public class DuplicateKeyException extends Exception {
+
+    public DuplicateKeyException(String s) {
+        super(s);
+    }
+
+}
@@ -0,0 +1,11 @@
+package com.baeldung.couchbase.mapreduce;
+
+import java.util.UUID;
+
+public class RandomUUIDGenerator<T> implements CouchbaseKeyGenerator<T> {
+
+    @Override
+    public String generateKey(T t) {
+        return UUID.randomUUID().toString();
+    }
+}
@@ -0,0 +1,50 @@
+package com.baeldung.couchbase.mapreduce;
+
+public class StudentGrade {
+
+    private String name;
+    private String course;
+    private Integer grade;
+    private Integer hours;
+    
+    public StudentGrade() { }
+    
+    public StudentGrade(String name, String course, Integer grade, Integer hours) {
+        this.name = name;
+        this.course = course;
+        this.grade = grade;
+        this.hours = hours;
+    }
+    
+    public String getName() {
+        return name;
+    }
+    
+    public void setName(String name) {
+        this.name = name;
+    }
+    
+    public String getCourse() {
+        return course;
+    }
+    
+    public void setCourse(String course) {
+        this.course = course;
+    }
+    
+    public Integer getGrade() {
+        return grade;
+    }
+    
+    public void setGrade(Integer grade) {
+        this.grade = grade;
+    }
+
+    public Integer getHours() {
+        return hours;
+    }
+
+    public void setHours(Integer hours) {
+        this.hours = hours;
+    }
+}
@@ -0,0 +1,9 @@
+package com.baeldung.couchbase.mapreduce;
+
+public class StudentGradeKeyGenerator implements CouchbaseKeyGenerator<StudentGrade> {
+
+    @Override
+    public String generateKey(StudentGrade g) {
+        return g.getName() + ":" + g.getCourse();
+    }
+}
@@ -0,0 +1,70 @@
+package com.baeldung.couchbase.mapreduce;
+
+import com.couchbase.client.deps.com.fasterxml.jackson.databind.ObjectMapper;
+import com.couchbase.client.java.document.json.JsonArray;
+import com.couchbase.client.java.view.ViewQuery;
+
+public class StudentGradeQueryBuilder {
+
+    final ObjectMapper om = new ObjectMapper();
+    
+    public ViewQuery findAll() {
+        return ViewQuery.from("studentGrades", "findByCourse");
+    }
+    
+    public ViewQuery findByCourse(String course) {
+        return ViewQuery.from("studentGrades", "findByCourse")
+                .key(course);
+    }
+    
+    public ViewQuery findByCourses(String... courses) {
+        return ViewQuery.from("studentGrades", "findByCourse")
+                .keys(JsonArray.from(courses));
+    }
+    
+    public ViewQuery findByGradeInRange(int lower, int upper, boolean inclusiveEnd) {
+        return ViewQuery.from("studentGrades", "findByGrade")
+                .startKey(lower)
+                .endKey(upper)
+                .inclusiveEnd(inclusiveEnd);
+    }
+    
+    public ViewQuery findByGradeLessThan(int upper) {
+        return ViewQuery.from("studentGrades", "findByGrade")
+                .endKey(upper)
+                .inclusiveEnd(false);
+    }
+    
+    public ViewQuery findByGradeGreaterThan(int lower) {
+        return ViewQuery.from("studentGrades", "findByGrade")
+                .startKey(lower);
+    }
+        
+    public ViewQuery findByCourseAndGradeInRange(String course, int minGrade, int maxGrade, boolean inclusiveEnd) {
+        return ViewQuery.from("studentGrades", "findByCourseAndGrade")
+                .startKey(JsonArray.from(course, minGrade))
+                .endKey(JsonArray.from(course, maxGrade))
+                .inclusiveEnd(inclusiveEnd);
+    }
+    
+    public ViewQuery findTopGradesByCourse(String course, int limit) {
+        return ViewQuery.from("studentGrades", "findByCourseAndGrade")
+                .startKey(JsonArray.from(course, 100))
+                .endKey(JsonArray.from(course, 0))
+                .inclusiveEnd(true)
+                .descending()
+                .limit(limit);
+    }
+    
+    public ViewQuery countStudentsByCourse() {
+        return ViewQuery.from("studentGrades", "countStudentsByCourse")
+                .reduce()
+                .groupLevel(1);
+    }
+    
+    public ViewQuery sumCreditsByStudent() {
+        return ViewQuery.from("studentGrades", "sumCreditsByStudent")
+                .reduce()
+                .groupLevel(1);
+    }
+}
@@ -0,0 +1,169 @@
+package com.baeldung.couchbase.mapreduce;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import com.couchbase.client.deps.com.fasterxml.jackson.databind.ObjectMapper;
+import com.couchbase.client.java.Bucket;
+import com.couchbase.client.java.CouchbaseCluster;
+import com.couchbase.client.java.document.JsonDocument;
+import com.couchbase.client.java.document.json.JsonArray;
+import com.couchbase.client.java.document.json.JsonObject;
+import com.couchbase.client.java.view.ViewQuery;
+import com.couchbase.client.java.view.ViewResult;
+import com.couchbase.client.java.view.ViewRow;
+
+public class StudentGradeService {
+
+    final CouchbaseKeyGenerator<StudentGrade> keyGenerator;
+    final CouchbaseCluster cluster;
+    final Bucket bucket;
+    final ObjectMapper om = new ObjectMapper();
+    final StudentGradeQueryBuilder queryBuilder;
+    
+    public StudentGradeService(CouchbaseKeyGenerator<StudentGrade> keyGenerator) {
+        this.keyGenerator = keyGenerator;
+        this.queryBuilder = new StudentGradeQueryBuilder();
+        cluster = CouchbaseCluster.create("127.0.0.1");
+        bucket = cluster.openBucket("baeldung-tutorial");
+    }
+    
+    public String insert(StudentGrade studentGrade) throws DuplicateKeyException {
+        String id = keyGenerator.generateKey(studentGrade);
+        if(bucket.exists(id)) {
+            throw new DuplicateKeyException("document already exists with key " + id);
+        }
+        JsonObject content = JsonObject.empty()
+                .put("type", "StudentGrade")
+                .put("name", studentGrade.getName())
+                .put("course", studentGrade.getCourse())
+                .put("grade", studentGrade.getGrade())
+                .put("hours", studentGrade.getHours());
+        JsonDocument doc = JsonDocument.create(id, content);
+        bucket.insert(doc);
+        return id;
+    }
+    
+    public List<JsonDocument> findAll() {
+        ViewQuery query = queryBuilder.findAll();
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+    
+    private List<JsonDocument> extractDocuments(ViewResult result) {
+        List<JsonDocument> docs = new ArrayList<>();
+        for(ViewRow row : result.allRows()) {
+            JsonDocument doc = row.document();
+            docs.add(doc);
+        }
+        return docs;
+    }
+    
+    public List<JsonDocument> findByCourse(String course) {
+        ViewQuery query = queryBuilder.findByCourse(course);
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+    
+    public List<JsonDocument> findByCourses(String... courses) {
+        ViewQuery query = queryBuilder.findByCourses(courses);
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+    
+    public List<JsonDocument> findByGradeInRange(int lower, int upper, boolean inclusiveEnd) {
+        ViewQuery query = queryBuilder.findByGradeInRange(lower, upper, inclusiveEnd);
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+    
+    public List<JsonDocument> findByGradeLessThan(int upper) {
+        ViewQuery query = queryBuilder.findByGradeLessThan(upper);
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+    
+    public List<JsonDocument> findByGradeGreaterThan(int lower) {
+        ViewQuery query = queryBuilder.findByGradeGreaterThan(lower);
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+        
+    public List<JsonDocument> findByCourseAndGradeInRange(String course, int minGrade, int maxGrade, boolean inclusiveEnd) {
+        ViewQuery query = queryBuilder.findByCourseAndGradeInRange(course, minGrade, maxGrade, inclusiveEnd);
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+    
+    public List<JsonDocument> findTopGradesByCourse(String course, int limit) {
+        ViewQuery query = queryBuilder.findTopGradesByCourse(course, limit);
+        ViewResult result = bucket.query(query);
+        return extractDocuments(result);
+    }
+    
+    public Map<String, Long> countStudentsByCourse() {
+        ViewQuery query = ViewQuery.from("studentGrades", "countStudentsByCourse")
+                .reduce()
+                .groupLevel(1);
+        ViewResult result = bucket.query(query);
+        
+        Map<String, Long> numStudentsByCourse = new HashMap<>();
+        for(ViewRow row : result.allRows()) {
+            JsonArray keyArray = (JsonArray) row.key();
+            String course = keyArray.getString(0);
+            long count = Long.valueOf(row.value().toString());
+            numStudentsByCourse.put(course, count);
+        }
+        
+        return numStudentsByCourse;
+    }
+    
+    public Map<String, Long> sumCreditHoursByStudent() {
+        ViewQuery query = ViewQuery.from("studentGrades", "sumHoursByStudent")
+                .reduce()
+                .groupLevel(1);
+        ViewResult result = bucket.query(query);
+        
+        Map<String, Long> creditHoursByStudent = new HashMap<>();
+        for(ViewRow row : result.allRows()) {
+            String course = (String) row.key();
+            long sum = Long.valueOf(row.value().toString());
+            creditHoursByStudent.put(course, sum);
+        }
+        
+        return creditHoursByStudent;
+    }
+    
+    public Map<String, Long> sumGradePointsByStudent() {
+        ViewQuery query = ViewQuery.from("studentGrades", "sumGradePointsByStudent")
+                .reduce()
+                .groupLevel(1);
+        ViewResult result = bucket.query(query);
+        
+        Map<String, Long> gradePointsByStudent = new HashMap<>();
+        for(ViewRow row : result.allRows()) {
+            String course = (String) row.key();
+            long sum = Long.valueOf(row.value().toString());
+            gradePointsByStudent.put(course, sum);
+        }
+        
+        return gradePointsByStudent;
+    }
+    
+    public Map<String, Float> calculateGpaByStudent() {
+        Map<String, Long> creditHoursByStudent = sumCreditHoursByStudent();
+        Map<String, Long> gradePointsByStudent = sumGradePointsByStudent();
+        
+        Map<String, Float> result = new HashMap<>();
+        for(Entry<String, Long> creditHoursEntry : creditHoursByStudent.entrySet()) {
+            String name = creditHoursEntry.getKey();
+            long totalHours = creditHoursEntry.getValue();
+            long totalGradePoints = gradePointsByStudent.get(name);
+            result.put(name, ((float) totalGradePoints / totalHours));
+        }
+        return result;
+    }
+}