CODEWITHSUNDEEP
javahibernatespring-mvc
QGA
QGA

Reputation: 3192

Cannot add or update a child row: a foreign key constraint fails Hibernate

SOLVED

Thanks to Predrag Maric I managed to find a bug which was that referencedColumnName was not referring to the right field. then I had to make the Table2 class implement the Serializable Interface and this made my test pass

Thanks for your help

Question

How can I map Table3 in Hibernate?

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This is my attempt:

@Entity
@Table(name="Table3")
public class Table3 implements Serializable
{
    @Id
    @GeneratedValue
    private long id;

    @NotNull
    @Column(name="field1")
    private String field1;

    @NotNull
    @Column(name="field2")
    private String field2;

    @ManyToOne
    @JoinColumn(name="Table2_id")
    private Table2 Table2_id ;

    @ManyToOne
    @JoinColumn(name="Table2_Table1_username")
    private Table2 Table2_Table1_username;

The error is in my JUnit test:

Cannot add or update a child row: a foreign key constraint fails (database.Table3, CONSTRAINTfk_Table3_Table2FOREIGN KEY (Table2_id,Table2_Table1_username) REFERENCESTable2(id,Table1_username) ON DELETE NO ACTION ON UPDATE NO ACTION)

Constructor:

Table3(String field1, String field2, Table2 table)
{
    this.field1 = field1;
    this.field2 = field2;
    this.Table2_id = table;
    this.Table2_Table1_username = table;
}

JUnit Test

@Before
    public void init() 
    {
        JdbcTemplate jdbc = new JdbcTemplate(dataSource);
        jdbc.execute("DELETE FROM Table3");
        jdbc.execute("DELETE FROM Table2");
        jdbc.execute("DELETE FROM Table1");
    }
 @Test
    public void testCreateMedia()
    {
        table1DAO.createTable(table1Object);
        table2DAO.createTable(table2Object);
        table3DAO.createTable(table3Object); //fails here
    }

Noted: I am not using java naming convention for variables

Upvotes: 1

Views: 1921

Answers (1)

Predrag Maric
Predrag Maric

Reputation: 24403

I think you misunderstood name and referencedColumnName in @JoinColumn.

name is the name of the column in source (Table3) table which is a foreign key to target (Table2) table.

referencedColumnName is the name of the column in target table which is a primari key (Table2.id). This attribute can be omitted in most cases.

In your case, it should look like this

@ManyToOne
@JoinColumn(name="Table2_id")
private Table2 Table2_id ;

@ManyToOne
@JoinColumn(name="Table2_Table1_username")
private Table2 Table2_Table1_username;

Upvotes: 3

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