使用HQL移除項條款

Question

「從哪裏是空刪除」我有一個關係

tag <-m:n-> software 

內的兩個實體，我想刪除這不是鏈接標記刪除特定的標籤後，再全部軟件。我寫的HQL查詢的..

我使用playframework

我重寫Tag.delete（）

@Override 
public Tag delete() { 

    Tag t = null; 

    // t = super.delete(); // commented for now 

    // it should delete ONLY that softwares which are not linked with tags (tags is empty) 
    Query q = Tag.em().createQuery("delete from Software s where s.tags is empty "); 
    q.executeUpdate(); 

    return t; 
} 

我的測試：

@Test 
public void testDelete() throws InterruptedException { 

    Tag tag1 = new Tag("tag1").save(); 
    Tag tag2 = new Tag("tag2").save(); 

    Author author1 = new Author("name", "email").save(); 

    Software s1 = new Software("soft1", "description1", author1, tag1).save(); // this should be deleted when tag1 is deleting 

    Software s2 = new Software("soft2", "description2", author1, tag1, tag2).save(); // this should be deleted, because it links to tag2 

    // checks, just in case: 
    Software ss = Software.findById(s1.id); 
    assertTrue(ss.isPersistent()); 
    assertTrue(!ss.tags.isEmpty()); 
    assertEquals(1, ss.tags.size()); 

    tag1.delete(); 

    // try to find the software 
    assertEquals(1, Software.findAll().size()); // here it faults, it deletes all!!! 
}  

現在我有問題它會刪除所有軟件，即使它們有鏈接到標籤。這是從HQL形成

，但我得到的SQL是這樣的：

delete from Software where not (exists (select tag.id from Tag_Software ts, Tag tag where Software.id=ts.softwares_id and ts.tags_id=tag.id))

，這是很好的SQL（我檢查），但爲什麼這一切不爲HQL工作我的背景......？

我的測試說：

故障，預計：< 1>卻被：< 0>

兩個類的代碼是：

public class Tag extends Model { 

    @Column(nullable = false, unique = true) 
    public String title; 

    public Tag(String title) { 
     this.title = title; 
    } 

    @ManyToMany 
    public List<Software> softwares = new LinkedList<Software>(); 

....

@Entity 
public class Software extends Model { 

    public String title; 
    public String description; 

    @ManyToOne(optional = false) 
    public Author author; 

    @ManyToMany(mappedBy = "softwares") 
    public List<Tag> tags = new LinkedList<Tag>(); 

...

Answer 1

有倍數的方式：

`softwares.size = 0

大小（軟件）= 0 `

你可以看到這篇詳細瞭解他們：

http://docs.jboss.org/hibernate/core/3.3/reference/en/html/queryhql.html#queryhql-expressions