Merge pull request #5607 from fanatixan/bael-2190

bael-2190

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

@@ -0,0 +1,71 @@
+package com.baeldung.manytomany.model;
+
+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 {
+
+    @Id
+    @Column(name = "id")
+    private Long id;
+
+    @ManyToMany(mappedBy = "likedCourses")
+    private Set<Student> likes;
+
+    @OneToMany(mappedBy = "course")
+    private Set<CourseRating> ratings;
+
+    @OneToMany(mappedBy = "course")
+    private Set<CourseRegistration> registrations;
+
+    // additional properties
+
+    public Course() {
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public Set<CourseRating> getRatings() {
+        return ratings;
+    }
+
+    public Set<CourseRegistration> getRegistrations() {
+        return registrations;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((id == null) ? 0 : id.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        Course other = (Course) obj;
+        if (id == null) {
+            if (other.id != null)
+                return false;
+        } else if (!id.equals(other.id))
+            return false;
+        return true;
+    }
+
+}

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

@@ -0,0 +1,79 @@
+package com.baeldung.manytomany.model;
+
+import javax.persistence.Column;
+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")
+public class CourseRating {
+
+    @EmbeddedId
+    private CourseRatingKey id;
+
+    @ManyToOne
+    @MapsId("student_id")
+    @JoinColumn(name = "student_id")
+    private Student student;
+
+    @ManyToOne
+    @MapsId("course_id")
+    @JoinColumn(name = "course_id")
+    private Course course;
+
+    @Column(name = "rating")
+    private int rating;
+
+    public CourseRating() {
+    }
+
+    public int getRating() {
+        return rating;
+    }
+
+    public void setRating(int rating) {
+        this.rating = rating;
+    }
+
+    public CourseRatingKey getId() {
+        return id;
+    }
+
+    public Student getStudent() {
+        return student;
+    }
+
+    public Course getCourse() {
+        return course;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((id == null) ? 0 : id.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        CourseRating other = (CourseRating) obj;
+        if (id == null) {
+            if (other.id != null)
+                return false;
+        } else if (!id.equals(other.id))
+            return false;
+        return true;
+    }
+
+}

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

@@ -0,0 +1,59 @@
+package com.baeldung.manytomany.model;
+
+import java.io.Serializable;
+
+import javax.persistence.Column;
+import javax.persistence.Embeddable;
+
+@Embeddable
+public class CourseRatingKey implements Serializable {
+
+    @Column(name = "student_id")
+    private Long studentId;
+
+    @Column(name = "course_id")
+    private Long courseId;
+
+    public CourseRatingKey() {
+    }
+
+    public Long getStudentId() {
+        return studentId;
+    }
+
+    public Long getCourseId() {
+        return courseId;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((courseId == null) ? 0 : courseId.hashCode());
+        result = prime * result + ((studentId == null) ? 0 : studentId.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        CourseRatingKey other = (CourseRatingKey) obj;
+        if (courseId == null) {
+            if (other.courseId != null)
+                return false;
+        } else if (!courseId.equals(other.courseId))
+            return false;
+        if (studentId == null) {
+            if (other.studentId != null)
+                return false;
+        } else if (!studentId.equals(other.studentId))
+            return false;
+        return true;
+    }
+
+}

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

@@ -0,0 +1,100 @@
+package com.baeldung.manytomany.model;
+
+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 {
+
+    @Id
+    @Column(name = "id")
+    private Long id;
+
+    @ManyToOne
+    @JoinColumn(name = "student_id")
+    private Student student;
+
+    @ManyToOne
+    @JoinColumn(name = "course_id")
+    private Course course;
+
+    @Column(name = "registered_at")
+    private LocalDateTime registeredAt;
+
+    @Column(name = "grade")
+    private int grade;
+
+    // additional properties
+
+    public CourseRegistration() {
+    }
+
+    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 LocalDateTime getRegisteredAt() {
+        return registeredAt;
+    }
+
+    public void setRegisteredAt(LocalDateTime registeredAt) {
+        this.registeredAt = registeredAt;
+    }
+
+    public int getGrade() {
+        return grade;
+    }
+
+    public void setGrade(int grade) {
+        this.grade = grade;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((id == null) ? 0 : id.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        CourseRegistration other = (CourseRegistration) obj;
+        if (id == null) {
+            if (other.id != null)
+                return false;
+        } else if (!id.equals(other.id))
+            return false;
+        return true;
+    }
+
+}

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

@@ -0,0 +1,78 @@
+package com.baeldung.manytomany.model;
+
+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 {
+
+    @Id
+    @Column(name = "id")
+    private Long id;
+
+    @ManyToMany
+    @JoinTable(name = "course_like", joinColumns = @JoinColumn(name = "student_id"), inverseJoinColumns = @JoinColumn(name = "course_id"))
+    private Set<Course> likedCourses;
+
+    @OneToMany(mappedBy = "student")
+    private Set<CourseRating> ratings;
+
+    @OneToMany(mappedBy = "student")
+    private Set<CourseRegistration> registrations;
+
+    // additional properties
+
+    public Student() {
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public Set<Course> getLikedCourses() {
+        return likedCourses;
+    }
+
+    public Set<CourseRating> getRatings() {
+        return ratings;
+    }
+
+    public Set<CourseRegistration> getRegistrations() {
+        return registrations;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((id == null) ? 0 : id.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        Student other = (Student) obj;
+        if (id == null) {
+            if (other.id != null)
+                return false;
+        } else if (!id.equals(other.id))
+            return false;
+        return true;
+    }
+
+}

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

@@ -0,0 +1,24 @@
+package com.baeldung.manytomany;
+
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+
+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;
+
+@RunWith(SpringRunner.class)
+@ContextConfiguration(classes = ManyToManyTestConfiguration.class)
+@DirtiesContext
+public class ManyToManyIntegrationTest {
+
+    @PersistenceContext
+    EntityManager entityManager;
+
+    @Test
+    public void contextStarted() {
+    }
+
+}

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

@@ -0,0 +1,51 @@
+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.JpaVendorAdapter;
+import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
+import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
+
+@Configuration
+@PropertySource("classpath:/manytomany/test.properties")
+public class ManyToManyTestConfiguration {
+
+    @Bean
+    public DataSource dataSource() {
+        EmbeddedDatabaseBuilder dbBuilder = new EmbeddedDatabaseBuilder();
+        return dbBuilder.setType(EmbeddedDatabaseType.H2)
+            .addScript("classpath:/manytomany/db.sql")
+            .build();
+    }
+
+    @Bean
+    public LocalContainerEntityManagerFactoryBean entityManagerFactory(@Value("${hibernate.hbm2ddl.auto}") String hbm2ddlType, @Value("${hibernate.dialect}") String dialect, @Value("${hibernate.show_sql}") boolean showSql) {
+        LocalContainerEntityManagerFactoryBean result = new LocalContainerEntityManagerFactoryBean();
+
+        result.setDataSource(dataSource());
+        result.setPackagesToScan("com.baeldung.manytomany.model");
+        result.setJpaVendorAdapter(jpaVendorAdapter());
+
+        Map<String, Object> jpaProperties = new HashMap<>();
+        jpaProperties.put("hibernate.hbm2ddl.auto", hbm2ddlType);
+        jpaProperties.put("hibernate.dialect", dialect);
+        jpaProperties.put("hibernate.show_sql", showSql);
+        result.setJpaPropertyMap(jpaProperties);
+
+        return result;
+    }
+
+    public JpaVendorAdapter jpaVendorAdapter() {
+        return new HibernateJpaVendorAdapter();
+    }
+
+}

persistence-modules/spring-jpa/src/test/resources/manytomany/db.sql

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+CREATE TABLE course (
+  id bigint(20) NOT NULL,
+  PRIMARY KEY (id)
+);
+
+
+CREATE TABLE student (
+  id bigint(20) NOT NULL,
+  PRIMARY KEY (id)
+);
+
+
+CREATE TABLE course_like (
+  student_id bigint(20) NOT NULL,
+  course_id bigint(20) NOT NULL,
+  PRIMARY KEY (student_id, course_id),
+  CONSTRAINT fk_course_like__student FOREIGN KEY (student_id) REFERENCES student (id),
+  CONSTRAINT fk_course_like__course FOREIGN KEY (course_id) REFERENCES course (id)
+);
+
+
+
+CREATE TABLE course_rating (
+  course_id bigint(20) NOT NULL,
+  student_id bigint(20) NOT NULL,
+  rating int(11) NOT NULL,
+  PRIMARY KEY (course_id, student_id),
+  CONSTRAINT fk_course_rating__student FOREIGN KEY (student_id) REFERENCES student (id),
+  CONSTRAINT fk_course_rating__course FOREIGN KEY (course_id) REFERENCES course (id)
+);
+
+
+
+CREATE TABLE course_registration (
+  id bigint(20) NOT NULL,
+  grade int(11),
+  registered_at datetime NOT NULL,
+  course_id bigint(20) NOT NULL,
+  student_id bigint(20) NOT NULL,
+  PRIMARY KEY (id),
+  CONSTRAINT fk_course_registration__student FOREIGN KEY (student_id) REFERENCES student (id),
+  CONSTRAINT fk_course_registration__course FOREIGN KEY (course_id) REFERENCES course (id)
+);
+

persistence-modules/spring-jpa/src/test/resources/manytomany/test.properties

@@ -0,0 +1,6 @@
+jdbc.driverClassName=org.h2.Driver
+jdbc.url=jdbc:h2:mem:myDb;DB_CLOSE_DELAY=-1
+
+hibernate.dialect=org.hibernate.dialect.H2Dialect
+hibernate.show_sql=true
+hibernate.hbm2ddl.auto=validate