Entity Framework: Assign entity to property of another entity

Question

I have these entities (this is just an abstraction I created for this post):

• Language
• District
• Description

These are the references between them:

• District * - 1 Language
• Description * - 1 Language
• District 1 - 1 Description

If I fetch like this:

var myFetch = from c in context.Districts
              where c.Id = 10
              select new { DistrictId = c.Id, Lang = c.Language };

and after that, I try to assign it to Description like this:

Description desc = Description.CreateDescription(0, "My description");
desc.DistrictReference.EntityKey = new EntityKey("MyEntities.Descriptions", "DistrictId", myFetch.DistrictId);
desc.Language = myFetch.Lang; //throws error

The error thrown is:

System.InvalidOperationException: The relationship cannot be defined because the EntitySet name 'MyEntities.Descriptions' is not valid for the role 'District' in association set name 'MyEntities.District_Description'.

What am I doing wrong?

Answer 1

if myFetch were to be an instance of the class District you could do it programmatically:

desc.DistrictReference.EntityKey = new EntityKey(  
  String.Format(  
    "{0}.{1}",   
    myFetch.EntityKey.EntityContainerName,   
    myFetch.EntityKey.EntitySetName),   
  "DistrictId", 
  myFetch.DistrictId);