Yea, what a stupid mistake I made :( Thanks!
On Wednesday, September 19, 2012 9:20:20 PM UTC+8, PeteA wrote:
>
> The 'child' object hasn't been added to the 'parent's Children collection
> in the first example, so there's nothing for NHibernate to cascade the
> delete onto (Children is empty). When you retrieve it from the DB in the
> 2nd piece of code the Children collection is populated and so NHibernate
> can cascade the deletion. So yes, it's a bug, but not in NH :). FWIW,
> when I have a bidirectional parent/child relationship I usually code the
> child's constructor to take the Parent object as a parameter:
>
>
>
> class Child {
>
> protected Child() {} // Required
>
> public Child(Parent myParent) {
>
> if(myParent != null) {
>
> this.Parent = myParent;
>
>
> myParent.Children.Add(this);
>
> } // else throw exception if the parent is
> mandatory
>
> }
>
>
>
> Pete
>
>
>
> *From:* [email protected] <javascript:> [mailto:
> [email protected] <javascript:>] *On Behalf Of *Mouhong Lin
> *Sent:* 19 September 2012 11:27
> *To:* [email protected] <javascript:>
> *Subject:* [nhusers] Save and delete (cascade delete) in the same session
> will fail
>
>
>
> Hi guys,
>
>
>
> *This is my model:*
>
>
>
> public class Category
>
> {
>
> public virtual int Id { get; set; }
>
>
>
> public virtual string Name { get; set; }
>
>
>
> public virtual Category Parent { get; set; }
>
>
>
> public virtual IList<Category> Children { get; protected set; }
>
>
>
> public Category()
>
> {
>
> Children = new List<Category>();
>
> }
>
> }
>
>
>
> This is the mapping:
>
>
>
> class CategoryMap : ClassMapping<Category>
>
> {
>
> public CategoryMap()
>
> {
>
> Table(typeof(Category).Name);
>
>
>
> this.HighLowId(c => c.Id);
>
>
>
> Property(c => c.Name);
>
>
>
> ManyToOne(c => c.Parent, m => m.Column("ParentId"));
>
>
>
> Bag(c => c.Children, m =>
>
> {
>
> m.Key(k => k.Column("ParentId"));
>
> m.Cascade(Cascade.All | Cascade.DeleteOrphans);
>
> m.Inverse(true);
>
> },
>
> m => m.OneToMany());
>
> }
>
> }
>
>
>
> *This is the database script:*
>
>
>
> create table Category
>
> (
>
> Id int not null,
>
> Name nvarchar(50) not null,
>
> ParentId int null,
>
>
>
> constraint PK_Category primary key (Id),
>
> constraint FK_Category_ParentId foreign key (ParentId)
> references Category(Id)
>
> )
>
>
>
> *This is the test code:*
>
>
>
> var parent = new Category { Name = "Category 1" };
>
> var child = new Category
>
> {
>
> Name = "Category 2",
>
> Parent = parent
>
> };
>
>
>
> using (var session = Database.OpenSession())
>
> {
>
> using (var tran = session.BeginTransaction())
>
> {
>
> session.Save(parent);
>
> session.Save(child);
>
>
>
> tran.Commit();
>
> }
>
>
>
> using (var tran = session.BeginTransaction())
>
> {
>
> session.Delete(parent);
>
> tran.Commit(); // Exception:
>
> }
>
> }
>
>
>
> The above code will cause this exception:
>
> The DELETE statement conflicted with the SAME TABLE REFERENCE constraint
> "FK_Category_ParentId". The conflict occurred in database "Test", table
> "dbo.Category", column 'ParentId'. The statement has been terminated."
>
>
>
> But if I delete the parent category in a *NEW *session, it will work:
>
>
>
> var parent = new Category { Name = "Category 1" };
>
> var child = new Category
>
> {
>
> Name = "Category 2",
>
> Parent = parent
>
> };
>
>
>
> using (var session = Database.OpenSession())
>
> {
>
> using (var tran = session.BeginTransaction())
>
> {
>
> session.Save(parent);
>
> session.Save(child);
>
>
>
> tran.Commit();
>
> }
>
> }
>
>
>
> using (var session = Database.OpenSession())
>
> {
>
> parent = session.Get<Category>(parent.Id);
>
>
>
> using (var tran = session.BeginTransaction())
>
> {
>
> session.Delete(parent);
>
> tran.Commit();
>
> }
>
> }
>
>
>
> Is this a bug? I'm using NHibernate.3.3.1.4000. Thanks :)
>
>
>
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