实体框架数据库优先配置

Question

I have the following tables in my database

Notes Table:

• NoteID
• Description
• TaskID (Can be NULL)

Task Table:

• TaskID
• TaskType
• TaskDescription

I an using Entity Framework 5.0 Database First approach.

In some cases there will be notes which linked to a single task but there will be cases that note are standalone that means that they not linked to single task.

My question is how do i need to configure the edmx (model) file so when i am asking for a single task he will give me the associated noted?

I think it something that i need to configure the mapping no?

Answer 1

You don't have to configure anything. Just gen the model from the db and then

 var query = context.Tasks.Include("Notes");

Answer 2

If you are doing code first then this will do it automatically. Simply make the TaskId nullable:

public class Note
{
    public int NoteID {get; set;}
    public string Description {get; set;}
    public int? TaskId {get; set;} // Notice the int is nullable

    public virtual Task {get; set;}
}

public class Task
{
    public int TaskID {get; set;}
    public TaskTypeEnum TaskType {get; set;}
    public string Description {get; set;}

    public virtual ICollection<Note> Notes {get; set;}
}