Question

我正在使用带有jpa注释的Spring-Data创建一个应用程序。

我在Question和Choice之间定义了多对多的关系，所以我有一个QuestionChoice对象来打破两个中的多对多关系。

我想要完成的是，在保存问题时，所有相关选项都会随问题一起保存/更新。

到目前为止，这是我的代码：

@Entity
@Table(name = "question")
public class Question {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "ID")
    private long id;


    @OneToMany(fetch = FetchType.EAGER, mappedBy = "question",
         cascade={CascadeType.PERSIST, CascadeType.MERGE})
    private Set<QuestionChoice> questionChoices;
…
}

@Entity
@Table(name="question_choice")
public class QuestionChoice {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="id")
    private long id;

    @ManyToOne
    @JoinColumn(name="questionId", referencedColumnName="id")
    private Question question;

    @ManyToOne(cascade={CascadeType.PERSIST, CascadeType.MERGE})
    @JoinColumn(name="choiceId", referencedColumnName="id")
    private Choice choice;

     …
 }

@Entity
@Table(name = "CHOICE")
public class Choice {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "ID")
    private long id;


    @OneToMany(mappedBy = "choice")
    private List<QuestionChoice> questions;
 …

}

@Repository
public interface QuestionRepository extends JpaRepository<Question,Long> {

}

代码工作得很好。当我创建一个新对象时，会正确创建Question，Question_Choice和Choice表记录。

问题是当我在保存Question对象后尝试添加新的Chocie时...存储库再次插入所有选项，而不是仅插入新添加的选项......

在下面的JUnit示例中，最后一个assertEquals告诉我有3个孩子而不是2个孩子：

@Test 
public void TestSaveQuestionAndAddChoices(){
    Question testQuestion = new Question();
    testQuestion.setDescription("Test");
    testQuestion.setClarification("Test Clarification");
    testQuestion.setAnswerExplanation("Test Answer");
    testQuestion.setLinkForAdditionalInformation("https://link5.com");
    testQuestion.setPoints(7);
    testQuestion.setTimeToAnswer(100);

    /** Check if the Question Id is correct Changed by the Save Method */
    Assert.assertEquals(0, testQuestion.getId());
    dao.getQuestionRepo().save(testQuestion);
    Assert.assertNotEquals(0, testQuestion.getId());

    /** Check Adding a Choice after the Question was saved & save*/
    Choice choice1 = new Choice("Test - Choice 1");
    testQuestion.addChoice(choice1, false);

    dao.getQuestionRepo().save(testQuestion);

    /* Retrieve the Question and verify the Size of the Array */
    Question retrievedQuestion =         dao.getQuestionRepo().findOne(testQuestion.getId());
    Assert.assertEquals(1, retrievedQuestion.getQuestionChoices().size());

    /** Check Adding a Second Choice and save  */       
    testQuestion.addChoice(new Choice("Test - Choice 2"), false);

    dao.getQuestionRepo().save(testQuestion);

    Question retrievedQuestion2 = dao.getQuestionRepo().findOne(testQuestion.getId());

    Assert.assertEquals(2, retrievedQuestion2.getQuestionChoices().size());

}

任何解释都会得到很大的解释。

更新时的Spring数据对象级联关系重复的子项

0 个答案: