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休眠-OneToMany仅检索一行

one-to-many hibernate postgresql java

Luke SpringWalker · 技术社区 · 7 年前

我有下面一节课 @OneToMany 关系,但它只返回两行中的一行:

@Entity
@javax.persistence.Table(name = "as_itm_ext")
public class ItemExtensionEntity implements java.io.Serializable {

    @OneToMany(fetch = FetchType.EAGER, cascade = { CascadeType.ALL })
    @JoinColumns({ @JoinColumn(name = "id_itm", referencedColumnName = "id_itm", insertable = false, updatable = false) })
    public Set<ItemAttributeEntity> getItemAttributeEntities() {
        return this.itemAttributeEntities;
    }

    public void setItemAttributeEntities(Set<ItemAttributeEntity> itemAttributeEntities) {
        this.itemAttributeEntities = itemAttributeEntities;
    }
}

以及要检索的类:

@Entity
@javax.persistence.Table(name = "as_itm_att")
public class ItemAttributeEntity implements java.io.Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * AttributeKey,The key of the attribute.
     */
    private ItemAttributeEntityId id;

    /**
     * AttributeValue,The value of the attribute.
     */
    private String attributeValue;

    public ItemAttributeEntity() {
    }

    public ItemAttributeEntity(ItemAttributeEntityId id, String attributeValue) {
        this.id = id;
        this.attributeValue = attributeValue;
    }

    /**
     * AttributeKey,The key of the attribute.
     */
    @EmbeddedId
    @AttributeOverrides({
            @AttributeOverride(name = "itemId", column = @Column(name = "id_itm", nullable = false, length = 32)),
            @AttributeOverride(name = "attributeKey", column = @Column(name = "att_key", nullable = false, length = 32)) })
    public ItemAttributeEntityId getId() {
        return this.id;
    }

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

    /**
     * AttributeValue,The value of the attribute.
     */
    @Column(name = "att_value", nullable = false, length = 32)
    public String getAttributeValue() {
        return this.attributeValue;
    }

    public void setAttributeValue(String attributeValue) {
        this.attributeValue = attributeValue;
    }

}

我已经试着改变 Set 到 List 但是运气不好(读了一点他们之间的差异之后,改变它是没有意义的)。

我不知道发生了什么,也不确定它是否总是这样。

谢谢

更新 :已尝试实施 equals ,什么也没发生。

2 回复 | 直到 7 年前

Anton Tupy 7 年前

尝试使用 fetch=FetchType。懒惰的 在…上 项目属性属性 .

Ankit 7 年前

根据我的理解,您需要添加以下引用(如@manytone) ItemExtensionEntity 在您的 ItemAttributeEntity 类别和在实体的@OneToMany注释中添加mappedby属性 项目扩展性

参考号: Can someone please explain mappedBy in hibernate?

@Entity
@javax.persistence.Table(name = "as_itm_ext")
public class ItemExtensionEntity implements java.io.Serializable {

    @OneToMany(mappedBy="parentEntity" ,fetch = FetchType.EAGER, cascade = { CascadeType.ALL })
    //@JoinColumns({ @JoinColumn(name = "id_itm", referencedColumnName = "id_itm", insertable = false, updatable = false) })
    public Set<ItemAttributeEntity> getItemAttributeEntities() {
        return this.itemAttributeEntities;
    }

    public void setItemAttributeEntities(Set<ItemAttributeEntity> itemAttributeEntities) {
        this.itemAttributeEntities = itemAttributeEntities;
    }
}


@Entity
@javax.persistence.Table(name = "as_itm_att")
public class ItemAttributeEntity implements java.io.Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * AttributeKey,The key of the attribute.
     */
    private ItemAttributeEntityId id;

    /**
     * AttributeValue,The value of the attribute.
     */
    private String attributeValue;

    @ManyToOne
    @JoinColumn(name="<columnname>", nullable=false)
    private ItemExtensionEntity parentEntity;

    //add getter and setters

    public ItemAttributeEntity() {
    }

    public ItemAttributeEntity(ItemAttributeEntityId id, String attributeValue) {
        this.id = id;
        this.attributeValue = attributeValue;
    }

    /**
     * AttributeKey,The key of the attribute.
     */
    @EmbeddedId
    @AttributeOverrides({
            @AttributeOverride(name = "itemId", column = @Column(name = "id_itm", nullable = false, length = 32)),
            @AttributeOverride(name = "attributeKey", column = @Column(name = "att_key", nullable = false, length = 32)) })
    public ItemAttributeEntityId getId() {
        return this.id;
    }

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

    /**
     * AttributeValue,The value of the attribute.
     */
    @Column(name = "att_value", nullable = false, length = 32)
    public String getAttributeValue() {
        return this.attributeValue;
    }

    public void setAttributeValue(String attributeValue) {
        this.attributeValue = attributeValue;
    }

}