Hibernate MappingException：外鍵必須具有與引用的主鍵相同的列數

Question

我有一個名為FatRabbitCarrot的實體：

@Entity
public class FatRabbitCarrot {
    private Long id;
    private FatRabbit fatRabbit;
    private Carrot carrot;

@Id
@Column(name = "id", nullable = false)
@GeneratedValue(strategy = GenerationType.IDENTITY)
public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

@ManyToOne
@JoinColumn(name = "fatRabbit_id", foreignKey = @ForeignKey(name = "FK_FatRabbitCarrot_fatRabbit"))
public FatRabbit getFatRabbit() {
    return fatRabbit;
}

public void setFatRabbit(FatRabbit fatRabbit) {
    this.fatRabbit = fatRabbit;
}

@ManyToOne
@JoinColumn(name = "carrot_id", foreignKey = @ForeignKey(name = "FK_FatRabbitCarrot_carrot"))
public Carrot getCarrot() {
    return carrot;
}

public void setCarrot(Carrot carrot) {
    this.carrot = carrot;
}
}

而且有效。 現在，上述類已替換了字段名稱，但結構與我們的存儲庫中的相同。

然后，我嘗試添加一個新實體，該實體具有上述類的外鍵。 我們稱此類為NutToffee。 FatRabbitCarrot與此新實體具有OneToMany關系，而實體本身應具有ManyToOne關系：

@Entity
public class NutToffee {

private Long id;
private String text;
private FatRabbitCarrot fatRabbitCarrot;

@Id
@Column(name = "id", nullable = false)
@GeneratedValue(strategy = GenerationType.IDENTITY)
public Long getId() {
    return id;
}

public void setId(Long id){
    this.id = id;
}

@Basic
@Column(name = "text")
public String getText() {
    return text;
}

public void setText(String text) {
    this.text = text;
}

@ManyToOne
@JoinColumn(name="fatRabbitCarrot_id", foreignKey = @ForeignKey(name = "FK_NutToffee_fatRabbitCarrot"))
public FatRabbitCarrot getFatRabbitCarrot() {
    return fatRabbitCarrot;
}

public void setFatRabbitCarrot(FatRabbitCarrot fatRabbitCarrot) {
    this.fatRabbitCarrot = fatRabbitCarrot;
}
}

現在這對我來說似乎是一個有效的課程。 但這看起來並不像。 我們正在使用Java 8，Hibernate JPA 2.1，Java EE 7和gradle構建我們要部署的工件。 我們嘗試將其部署在Wildfly 10應用程序服務器上，但是出現以下錯誤：

[2019-07-08 03:53:45,441] Artifact Gradle : com.solveralynx.wildrunner : fatties.war: java.lang.Exception: {"WFLYCTL0080: Failed services" => {"jboss.persistenceunit.\"fatties.war#FatUnit\"" => "org.jboss.msc.service.StartException in service jboss.persistenceunit.\"fatties.war#FatUnit\": org.hibernate.MappingException: Foreign key (FK_NutToffee_fatRabbitCarrot:NutToffee [fatRabbitCarrot_id])) must have same number of columns as the referenced primary key (FatRabbitCarrot [fatRabbit_id,carrot_id])
Caused by: org.hibernate.MappingException: Foreign key (FK_NutToffee_fatRabbitCarrot:NutToffee [fatRabbitCarrot_id])) must have same number of columns as the referenced primary key (FatRabbitCarrot [fatRabbit_id,carrot_id])"},"WFLYCTL0412: Required services that are not installed:" => ["jboss.persistenceunit.\"fatties.war#FatUnit\""],"WFLYCTL0180: Services with missing/unavailable dependencies" => undefined}

據我了解，Hibernate找到了FatRabbitCarrot的復合主鍵？ 即使我們從未定義一個？ 似乎撿到了一個偽造的主鍵，在其中它使用了來自實體FatRabbitCarrot的兩個外鍵。

至於我的測試。 我相信這是一個休眠問題。 無論數據庫狀態如何，我總是會收到此錯誤。 我在連接該實體的吸氣劑上測試了各種參數，但沒有成功。 如果我同時刪除了新的OneToMany和ManyToOne連接，則將部署工件。

有誰知道為什么Hibernate這樣做？

Answer 1

您使用的@JoinColumn注解不正確。

@Entity
public class FatRabbitCarrot {

    @Id
    @GeneratedValue
    private Long id;

    @OnToMany
    private List<NutToffee> toffies;

}

@Entity
public class NutToffee {

    @Id
    @GeneratedValue
    private Long id;

    @ManyToOne
    @JoinColumn(name = "fatRabbitCarrot_id")
    private FatRabbitCarrot fatRabbitCarrot;

}

這意味着您將使用NutToffee表在FatRabbitCarrot和NutToffee之間FatRabbitCarrot關聯。 您將在NutToffee表中增加一個fatRabbitCarrot_id列。

您需要使用mappedBy

    @Entity
    public class FatRabbitCarrot {

        @Id
        @GeneratedValue
        private Long id;

        @OnToMany(mappedBy = "fatRabbitCarrot")
        private List<NutToffee> toffies;

    }

    @Entity
    public class NutToffee {

        @Id
        @GeneratedValue
        private Long id;

        @ManyToOne
        @JoinColumn(name = "fatRabbitCarrot_id")
        private FatRabbitCarrot fatRabbitCarrot;

    }

如果你不需要@ManyToOne關聯，您可以使用@JoinColumn與@OneToMany沒有mappedBy

    @Entity
    public class FatRabbitCarrot {

        @Id
        @GeneratedValue
        private Long id;

        @OnToMany
        @JoinColumn(name = "fatRabbitCarrot_id")
        private List<NutToffee> toffies;

    }

    @Entity
    public class NutToffee {

        @Id
        @GeneratedValue
        private Long id;


    }

https://stackoverflow.com/a/37542849/3405171