本章来看看Castle ActiveRecord中的级联(cascade)操作

还是以post和comment为例

post.cs 修改为

1:  [ActiveRecord("Posts")]

2:  public class Post : ActiveRecordBase
     

3:  {

4:      [PrimaryKey("PostId")]

5:      public int Id { get; set; }

6:   

7:      [Property]

8:      public string Subject { get; set; }

9:   

10:      [Property]

11:      public string Text { get; set; }

12:   

13:      [Property]

14:      public DateTime DateAdded { get; set; }

15:   

16:      [BelongsTo("CategoryId")]

17:      public Category Category { get; set; }

18:   

19:      [HasMany(Lazy=true,Cascade=ManyRelationCascadeEnum.AllDeleteOrphan,Inverse = true)]

20:      public IList
     
       Comments { get; set; }
     

21:   

22:      [HasAndBelongsToMany(typeof(Tag), Table = "TagPost", ColumnKey = "PostId", ColumnRef = "TagId")]

23:      public IList
     
       Tag { get; set; }
     

24:   

25:  }

HasMany特性添加Cascade

枚举属性

枚举	值
ManyRelationCascadeEnum	None	不做级联操作
	All	增删改都做级联操作
	AllDeleteOrphan	都做级联操作，并且删除孤儿数据。即删除没有对应Post的Comment对象
	SaveUpdate	在增加和更新的时候做级联操作
	Delete	在删除的时候做级联操作

1、级联添加

创建一个post ，并添加多个comment

1:  //创建post

2:  Post post = new Post();

3:  post.DateAdded = DateTime.Now;

4:  post.Subject = "castle active record 7";

5:  post.Text = "content";

6:  List
      
        list = new List
       
        ();
       
      

7:  list.Add(1);

8:  list.Add(2);

9:  post.Category = Category.Find(5);

10:  post.Tag = Tag.FindAll();

11:  using (TransactionScope tran=new TransactionScope ())

12:  {

13:      try

14:      {

15:          post.Create();

16:          for (int i = 0; i < 10; i++)

17:          {

18:              //创建comment

19:              Comment comment = new Comment();

20:              comment.Author = "hzd" + i;

21:              comment.DateAdded = DateTime.Now;

22:              comment.Text = "comment" + i + " content!";

23:              comment.Post = post;

24:              comment.Save();

25:          }

26:          tran.VoteCommit();

27:

28:      }

29:      catch

30:      {

31:          tran.VoteRollBack();

32:      }

33:  }

2、级联更新

为已经存在的post 添加 comment

1:  Post post = new Post();

2:  post = Post.Find(8);

3:  using (TransactionScope tran=new TransactionScope ())

4:  {

5:      try

6:      {

7:          for (int i = 0; i < 5; i++)

8:          {

9:              //创建comment

10:              Comment comment = new Comment();

11:              comment.Author = "hzd-" + i;

12:              comment.DateAdded = DateTime.Now;

13:              comment.Text = "comment" + i + " content!";

14:              comment.Post = post;

15:              comment.Save();

16:          }

17:          post.Text = "castle active record  Cascade";

18:          post.Update();

19:          tran.VoteCommit();

20:

21:      }

22:      catch

23:      {

24:          tran.VoteRollBack();

25:      }

26:  }

27:   

3、级联删除

删除一个post

1:  Post post = new Post();

2:  post = Post.Find(1);

3:  post.Delete();

删除一个post的一个comment

1:  using (new SessionScope())

2:  {

3:      Post post = new Post();

4:      post = Post.Find(8);

5:      int count = post.Comments.Count;

6:      post.Comments.RemoveAt(0);

7:      post.Update();

8:  }

特别注意

1:  [HasMany(Lazy = true, Cascade = ManyRelationCascadeEnum.AllDeleteOrphan, Inverse = true)]

2:  public IList
     
       Comments { get; set; }
     

设置One-To-Many 中 One方(本文中的post) HasManyAttribute的Inverse属性为true

Inverse属性指定了双向关联中的所有者，它的默认值为false。

Inverse 为true是，关联关系的维护者为 主表(即posts表)。

为false时，关联关系的维护者为 子表(即comments表)，如果子表设置了外键不为null，会出现

不能将值 NULL 插入列 '外键列'

的错误。