Hibernate 休眠双向关系
如何在hibernate中建立双向关系@OneToMany 我有3个表useraccount、category和item。在MyItem表中,它保存useraccount和category的外键。如果我建立单向,它将在item类中使用如下代码编译:Hibernate 休眠双向关系,hibernate,Hibernate,如何在hibernate中建立双向关系@OneToMany 我有3个表useraccount、category和item。在MyItem表中,它保存useraccount和category的外键。如果我建立单向,它将在item类中使用如下代码编译: @ManyToOne @JoinColumn(name="cat_id") public Category getCategory() { return category; } public void setCategory(Category
@ManyToOne
@JoinColumn(name="cat_id")
public Category getCategory() { return category; }
public void setCategory(Category category) {this.category = category; }
private Category category;
@ManyToOne
@JoinColumn(name="user_id")
public UserAccount getItemOwner() { return itemOwner; }
public void setItemOwner(UserAccount itemOwner) { this.itemOwner = itemOwner; }
private UserAccount itemOwner;
但当我试图通过在useraccount和category中添加这些映射来定义双向时:
@OneToMany(mappedBy="USERACCOUNTS", targetEntity=Item.class, cascade=CascadeType.ALL)
public Set<Item> getOwnedItems() { return ownedItems; }
public void setOwnedItems(Set<Item> ownedItems) { this.ownedItems = ownedItems; }
private Set<Item> ownedItems;
@OneToMany(mappedBy="CATEGORIES", targetEntity=Item.class, cascade=CascadeType.ALL)
public Set<Item> getListOfItem() { return listOfItem; }
public void setListOfItem(Set<Item> listOfItem) { this.listOfItem = listOfItem; }
private Set<Item>listOfItem;
我看了文件,但找不出问题出在哪里。谁能给我一些建议来解决这个问题。感谢注释
@JoinColumn
表示此实体是关系的所有者(即:对应的表中有一列包含引用表的外键),而属性mappedBy
表示此侧的实体是关系的反向,所有者位于“其他”实体中
根据:
由于在JPA规范中,多对一几乎总是双向关系的所有者方,一对多关联由@OneToMany注释(mappedBy=…)
你对@OneToMany的所有“mappedBy”都是错的。其值应为另一端的属性名称,请尝试按以下方式配置:
@OneToMany(mappedBy="itemOwner", cascade=CascadeType.ALL)
public Set<Item> getOwnedItems() { return ownedItems; }
@OneToMany(mappedBy=“itemOwner”,cascade=CascadeType.ALL)
公共集getOwnedItems(){return ownedItems;}
及
@OneToMany(mappedBy=“category”,cascade=CascadeType.ALL)
公共集GetListoItem(){return ListoItem;}
@Entity
public class Troop {
@OneToMany(mappedBy="troop")
public Set<Soldier> getSoldiers() {
...
}
@Entity
public class Soldier {
@ManyToOne
@JoinColumn(name="troop_fk")
public Troop getTroop() {
...
}
@Entity
public class Troop {
@OneToMany
@JoinColumn(name="troop_fk") //we need to duplicate the physical information
public Set<Soldier> getSoldiers() {
...
}
@Entity
public class Soldier {
@ManyToOne
@JoinColumn(name="troop_fk", insertable=false, updatable=false)
public Troop getTroop() {
...
}
@OneToMany(mappedBy="itemOwner", cascade=CascadeType.ALL)
public Set<Item> getOwnedItems() { return ownedItems; }
@OneToMany(mappedBy="category", cascade=CascadeType.ALL)
public Set<Item> getListOfItem() { return listOfItem; }