jpql 加入查询答案

【问题标题】：jpql Join queryjpql 加入查询
【发布时间】：2011-09-17 17:43:17
【问题描述】：

我在两个名为 Menu 和 Previlege 的表之间有一个名为 MenuPrevilege 的关联表。为了获取特定权限的所有菜单，我在菜单实体中创建了一个命名查询：

   @Entity
   @NamedQueries( {
   @NamedQuery(name = "getAllMenus", query = "select m from Menu m"),
   @NamedQuery(name = "getMenusByPrevilegeId", query = "select m from Menu m
            JOIN m.menuPrevilege mp where mp.previlege_id = :p")})


public class Menu implements Serializable {

private String url;
private String description;
private List<MenuPrevilege> menuPrevilges;
private static final long serialVersionUID = 1L;

public Menu() {
    super();
}

@Id
public String getUrl() {
    return this.url;
}

public void setUrl(String url) {
    this.url = url;
}

public String getDescription() {
    return this.description;
}

public void setDescription(String description) {
    this.description = description;
}

public void setMenuPrevilges(List<MenuPrevilege> menuPrevilges) {
    if (menuPrevilges == null)
        menuPrevilges = new ArrayList<MenuPrevilege>();
    this.menuPrevilges = menuPrevilges;
}

@OneToMany(mappedBy = "menu", cascade = CascadeType.REMOVE)
public List<MenuPrevilege> getMenuPrevilges() {
    if (menuPrevilges == null)
        menuPrevilges = new ArrayList<MenuPrevilege>();
    return menuPrevilges;
}

public Menu(String url, String description) {
    super();
    this.url = url;
    this.description = description;
}
    }

我遇到了这个异常 org.hibernate.QueryException: could not resolve property:menuPrevilege ，我不知道如何处理它。这是 MenuPrevilege 实体：

    @Entity
    @Table(name = "Menu_Previlege")

    public class MenuPrevilege implements Serializable {

private IdMenuPrevilege idmenuPrevilege = new IdMenuPrevilege();
private Date activationDate;
private Date deactivationDate;
private Menu menu;
private Previlege previlege;
private static final long serialVersionUID = 1L;

public MenuPrevilege() {
    super();
}

@EmbeddedId
public IdMenuPrevilege getIdmenuPrevilege() {
    return this.idmenuPrevilege;
}

public void setIdmenuPrevilege(IdMenuPrevilege idmenuPrevilege) {
    this.idmenuPrevilege = idmenuPrevilege;
}

@Temporal(TemporalType.DATE)
public Date getActivationDate() {
    return this.activationDate;
}

public void setActivationDate(Date activationDate) {
    this.activationDate = activationDate;
}

@Temporal(TemporalType.DATE)
public Date getDeactivationDate() {
    return this.deactivationDate;
}

public void setDeactivationDate(Date deactivationDate) {
    this.deactivationDate = deactivationDate;
}

public void setMenu(Menu menu) {
    this.menu = menu;
}

@ManyToOne
@JoinColumn(name = "menu_id", insertable = false, updatable = false)
public Menu getMenu() {
    return menu;
}

public void setPrevilege(Previlege previlege) {
    this.previlege = previlege;
}

@ManyToOne
@JoinColumn(name = "previlege_id", insertable = false, updatable = false)
public Previlege getPrevilege() {
    return previlege;
}

public MenuPrevilege(Menu menu, Previlege previlege) {
    super();
    getIdmenuPrevilege().setIdMenu(menu.getUrl());
    getIdmenuPrevilege().setIdPrevilege(previlege.getPrevilegeId());
    this.setMenu(menu);
    this.setPrevilege(previlege);
    menu.getMenuPrevilges().add(this);
    previlege.getPrevilegeMenus().add(this);
}

  }

【问题讨论】：

标签： jsf join ejb-3.0 jpql

【解决方案1】：

我对我的代码进行了名称重构，编辑了我的查询，一切似乎都在工作。以下是变化：

在命名查询中：

@NamedQuery(name = "getMenusByPrevilegeId", query = "select m from Menu m  JOIN 
 m.previleges p where p.previlege.previlegeId = :p")})

实体属性

private List<MenuPrevilege> previleges;
// getters and setters as well

在 MenuPrevilege 实体的构造函数中

public MenuPrevilege(Menu menu, Previlege previlege) {
super();
getIdmenuPrevilege().setIdMenu(menu.getUrl());
getIdmenuPrevilege().setIdPrevilege(previlege.getPrevilegeId());
this.setMenu(menu);
this.setPrevilege(previlege);
menu.getPrevileges().add(this);
previlege.getMenus().add(this);
}

您可以注意到这是我的查询中的语法错误导致了异常。

【讨论】：