Linq to SQL-删除子属性

Question

I'm trying to delete a child property of a domain entity. In the UI, the user selects Delete to remove a CustomVariableGroup from an Application entity.

I thought deleting the property from the LINQ-to-SQL entity & then submitting changes, would cause LINQ-to-SQL to take care of the work on the Database side. But the row never gets deleted from the table. When I refresh the page in my application, the property is still there because it's still there in the Database.

public void Save(Application application)
{
    ApplicationRecord appRecord = application.Map();  // Maps domain entity to L2S entity

    // Before this line executes, appRecord has 0 CustomVariableGroups, which is correct.
    this.Database.ApplicationRecords.Attach(appRecord, true);
    // After the attach, appRecord now has 1 CustomVariableGroup again. This is wrong.

    appRecord = application.Map();  // Hack to remove the CustomVariableGroup again.

    // This doesn't delete the CustomVariableGroup from appRecord. Do I need
    // to delete it explicitly? Or should removing it from appRecord, and
    // calling SubmitChanges() do it?
    this.Database.SubmitChanges();
}

What is the right way for me to get rid of this child property on the entity? I guess I could loop through the list and delete each item individually, but I don't think LINQ-to-SQL is supposed to work that way.

Any ideas are appreciated.

Note: The property ApplicationCustomVariableGroupRecords represents a table that resolves a many-to-many association in the Database. An Application can have one or more CustomVariableGroups , and a CustomVariableGroup can belong to one or more Applications .

Answer 1

Normally you have to specifically delete the object - removing it from a parent collection just means you don't want it to be associated with that particular parent anymore. It can't tell that you don't want to then associate it with a different parent. If you want it to get deleted, you need to make the call to have it deleted (DeleteOnSubmit for L2S, IIRC)

Answer 2

if im not wrong the tables which have n to n relations between them are works like nested..So try to first delete from the 3rd table (which contains IDs of 2 table) and then remove from main table..

[Sorry, i can't see add comment button on the page.. so i wrote this idea as answer ]