BAEL-4577: Fix @MapsIs usage and add integration test (#9930)

persistence-modules/spring-jpa-2/src/main/java/com/baeldung/manytomany/model/Course.java

@@ -1,14 +1,9 @@
 package com.baeldung.manytomany.model;
 
+import javax.persistence.*;
+import java.util.HashSet;
 import java.util.Set;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.ManyToMany;
-import javax.persistence.OneToMany;
-import javax.persistence.Table;
-
 @Entity
 @Table(name = "course")
 public class Course {
@@ -18,31 +13,55 @@ public class Course {
     private Long id;
 
     @ManyToMany(mappedBy = "likedCourses")
-    private Set<Student> likes;
+    private Set<Student> likes = new HashSet<>();
 
     @OneToMany(mappedBy = "course")
-    private Set<CourseRating> ratings;
+    private Set<CourseRating> ratings = new HashSet<>();
 
     @OneToMany(mappedBy = "course")
-    private Set<CourseRegistration> registrations;
+    private Set<CourseRegistration> registrations = new HashSet<>();
 
     // additional properties
 
     public Course() {
     }
 
+    public Course(Long id) {
+        this.id = id;
+    }
+
     public Long getId() {
         return id;
     }
 
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Set<Student> getLikes() {
+        return likes;
+    }
+
+    public void setLikes(Set<Student> likes) {
+        this.likes = likes;
+    }
+
     public Set<CourseRating> getRatings() {
         return ratings;
     }
 
+    public void setRatings(Set<CourseRating> ratings) {
+        this.ratings = ratings;
+    }
+
     public Set<CourseRegistration> getRegistrations() {
         return registrations;
     }
 
+    public void setRegistrations(Set<CourseRegistration> registrations) {
+        this.registrations = registrations;
+    }
+
     @Override
     public int hashCode() {
         final int prime = 31;

persistence-modules/spring-jpa-2/src/main/java/com/baeldung/manytomany/model/CourseRating.java

@@ -1,12 +1,6 @@
 package com.baeldung.manytomany.model;
 
-import javax.persistence.Column;
+import javax.persistence.*;
-import javax.persistence.EmbeddedId;
-import javax.persistence.Entity;
-import javax.persistence.JoinColumn;
-import javax.persistence.ManyToOne;
-import javax.persistence.MapsId;
-import javax.persistence.Table;
 
 @Entity
 @Table(name = "course_rating")
@@ -16,12 +10,12 @@ public class CourseRating {
     private CourseRatingKey id;
 
     @ManyToOne
-    @MapsId("student_id")
+    @MapsId("studentId")
     @JoinColumn(name = "student_id")
     private Student student;
 
     @ManyToOne
-    @MapsId("course_id")
+    @MapsId("courseId")
     @JoinColumn(name = "course_id")
     private Course course;
 
@@ -31,26 +25,38 @@ public class CourseRating {
     public CourseRating() {
     }
 
-    public int getRating() {
-        return rating;
-    }
-
-    public void setRating(int rating) {
-        this.rating = rating;
-    }
-
     public CourseRatingKey getId() {
         return id;
     }
 
+    public void setId(CourseRatingKey id) {
+        this.id = id;
+    }
+
     public Student getStudent() {
         return student;
     }
 
+    public void setStudent(Student student) {
+        this.student = student;
+    }
+
     public Course getCourse() {
         return course;
     }
 
+    public void setCourse(Course course) {
+        this.course = course;
+    }
+
+    public int getRating() {
+        return rating;
+    }
+
+    public void setRating(int rating) {
+        this.rating = rating;
+    }
+
     @Override
     public int hashCode() {
         final int prime = 31;

persistence-modules/spring-jpa-2/src/main/java/com/baeldung/manytomany/model/CourseRatingKey.java

@@ -1,9 +1,8 @@
 package com.baeldung.manytomany.model;
 
-import java.io.Serializable;
-
 import javax.persistence.Column;
 import javax.persistence.Embeddable;
+import java.io.Serializable;
 
 @Embeddable
 public class CourseRatingKey implements Serializable {
@@ -17,14 +16,27 @@ public class CourseRatingKey implements Serializable {
     public CourseRatingKey() {
     }
 
+    public CourseRatingKey(Long studentId, Long courseId) {
+        this.studentId = studentId;
+        this.courseId = courseId;
+    }
+
     public Long getStudentId() {
         return studentId;
     }
 
+    public void setStudentId(Long studentId) {
+        this.studentId = studentId;
+    }
+
     public Long getCourseId() {
         return courseId;
     }
 
+    public void setCourseId(Long courseId) {
+        this.courseId = courseId;
+    }
+
     @Override
     public int hashCode() {
         final int prime = 31;

persistence-modules/spring-jpa-2/src/main/java/com/baeldung/manytomany/model/CourseRegistration.java

@@ -1,14 +1,8 @@
 package com.baeldung.manytomany.model;
 
+import javax.persistence.*;
 import java.time.LocalDateTime;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.JoinColumn;
-import javax.persistence.ManyToOne;
-import javax.persistence.Table;
-
 @Entity
 @Table(name = "course_registration")
 public class CourseRegistration {
@@ -36,6 +30,14 @@ public class CourseRegistration {
     public CourseRegistration() {
     }
 
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
     public Student getStudent() {
         return student;
     }
@@ -68,10 +70,6 @@ public class CourseRegistration {
         this.grade = grade;
     }
 
-    public Long getId() {
-        return id;
-    }
-
     @Override
     public int hashCode() {
         final int prime = 31;

persistence-modules/spring-jpa-2/src/main/java/com/baeldung/manytomany/model/Student.java

@@ -1,16 +1,9 @@
 package com.baeldung.manytomany.model;
 
+import javax.persistence.*;
+import java.util.HashSet;
 import java.util.Set;
 
-import javax.persistence.Column;
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.JoinColumn;
-import javax.persistence.JoinTable;
-import javax.persistence.ManyToMany;
-import javax.persistence.OneToMany;
-import javax.persistence.Table;
-
 @Entity
 @Table(name = "student")
 public class Student {
@@ -21,35 +14,55 @@ public class Student {
 
     @ManyToMany
     @JoinTable(name = "course_like", joinColumns = @JoinColumn(name = "student_id"), inverseJoinColumns = @JoinColumn(name = "course_id"))
-    private Set<Course> likedCourses;
+    private Set<Course> likedCourses = new HashSet<>();
 
     @OneToMany(mappedBy = "student")
-    private Set<CourseRating> ratings;
+    private Set<CourseRating> ratings = new HashSet<>();
 
     @OneToMany(mappedBy = "student")
-    private Set<CourseRegistration> registrations;
+    private Set<CourseRegistration> registrations = new HashSet<>();
 
     // additional properties
 
     public Student() {
     }
 
+    public Student(Long id) {
+        this.id = id;
+    }
+
     public Long getId() {
         return id;
     }
 
+    public void setId(Long id) {
+        this.id = id;
+    }
+
     public Set<Course> getLikedCourses() {
         return likedCourses;
     }
 
+    public void setLikedCourses(Set<Course> likedCourses) {
+        this.likedCourses = likedCourses;
+    }
+
     public Set<CourseRating> getRatings() {
         return ratings;
     }
 
+    public void setRatings(Set<CourseRating> ratings) {
+        this.ratings = ratings;
+    }
+
     public Set<CourseRegistration> getRegistrations() {
         return registrations;
     }
 
+    public void setRegistrations(Set<CourseRegistration> registrations) {
+        this.registrations = registrations;
+    }
+
     @Override
     public int hashCode() {
         final int prime = 31;

persistence-modules/spring-jpa-2/src/test/java/com/baeldung/manytomany/ManyToManyIntegrationTest.java

@@ -1,17 +1,27 @@
 package com.baeldung.manytomany;
 
-import javax.persistence.EntityManager;
+import com.baeldung.manytomany.model.Course;
-import javax.persistence.PersistenceContext;
+import com.baeldung.manytomany.model.CourseRating;
-
+import com.baeldung.manytomany.model.CourseRatingKey;
+import com.baeldung.manytomany.model.Student;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.transaction.annotation.Transactional;
+
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.notNullValue;
+import static org.junit.Assert.assertThat;
 
 @RunWith(SpringRunner.class)
 @ContextConfiguration(classes = ManyToManyTestConfiguration.class)
 @DirtiesContext
+@Transactional
 public class ManyToManyIntegrationTest {
 
     @PersistenceContext
@@ -21,4 +31,25 @@ public class ManyToManyIntegrationTest {
     public void contextStarted() {
     }
 
+    @Test
+    public void whenCourseRatingPersisted_thenCorrect() {
+        Student student = new Student(101L);
+        entityManager.persist(student);
+
+        Course course = new Course(201L);
+        entityManager.persist(course);
+
+        CourseRating courseRating = new CourseRating();
+        courseRating.setId(new CourseRatingKey());
+        courseRating.setStudent(student);
+        courseRating.setCourse(course);
+        courseRating.setRating(100);
+        entityManager.persist(courseRating);
+
+        CourseRating persistedCourseRating = entityManager.find(CourseRating.class, new CourseRatingKey(101L, 201L));
+
+        assertThat(persistedCourseRating, notNullValue());
+        assertThat(persistedCourseRating.getStudent().getId(), is(101L));
+        assertThat(persistedCourseRating.getCourse().getId(), is(201L));
+    }
 }

persistence-modules/spring-jpa-2/src/test/java/com/baeldung/manytomany/ManyToManyTestConfiguration.java

@@ -1,20 +1,21 @@
 package com.baeldung.manytomany;
 
-import java.util.HashMap;
-import java.util.Map;
-
-import javax.sql.DataSource;
-
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.PropertySource;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
+import org.springframework.orm.jpa.JpaTransactionManager;
 import org.springframework.orm.jpa.JpaVendorAdapter;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
 import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
 
+import javax.persistence.EntityManagerFactory;
+import javax.sql.DataSource;
+import java.util.HashMap;
+import java.util.Map;
+
 @Configuration
 @PropertySource("manytomany/test.properties")
 public class ManyToManyTestConfiguration {
@@ -44,6 +45,13 @@ public class ManyToManyTestConfiguration {
         return result;
     }
 
+    @Bean
+    JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
+        JpaTransactionManager transactionManager = new JpaTransactionManager();
+        transactionManager.setEntityManagerFactory(entityManagerFactory);
+        return transactionManager;
+    }
+
     public JpaVendorAdapter jpaVendorAdapter() {
         return new HibernateJpaVendorAdapter();
     }