Entity Framework 4 (using EDMX), how to add a field into to model that DB does not have the field actually

Question

I need to add a field into model that Database does not have the field actually.

Because, firstly I tried to add the field into Entity class only.

public partial class Weborder
{
  (Auto Generated)
  public int orderno {get; set;}
  .
  .
  .
  (Add Manually)
  public string newField1 {get; set;} //this is new field that DB does not have
  public string newField2 {get; set;} //this is new field that DB does not have
}

and later, when I update EDXM then EDMX remove the new fields because the database does not have the field. :(

So I add the field into EDMX model manually. (Add -> Scalar Property)

then an error occur while compiling, the error message say :

Error   1   Error 3004: Problem in mapping fragments starting at line 399:No mapping specified for properties ...
An Entity with Key (PK) will not round-trip when:...

Anybody know how to add new fields into entity class ?

Thank you!

EDITED FOR : If your model is a representation of your database and in the database you don't have the field, why do you want to add it manually?

=>

When retrieve data, the return type of object is the entity class.

and before passing data from controller to view, I need to add more data(fields) into the IQueryable result.

ex)

public DbSet<WEBORDERLN> WEBORDERLNs { get; set; }

//repository
public IQueryable<WEBORDERLN> WebOrderLns
{
      get { return context.WEBORDERLNs; }
}

and now I get the weborderln data in controller. and before passing view, I need to

add extra data into the result.

var data = webOrderLnRepository.WebOrderLns.Where(e => e.PICKNO == OrderNo).ToList();

foreach (WEBORDERLN weborderln in data)
{
   weborderln.[NEW FIELD] = "EXTRA DATA";   //// FOR THIS, I NEED TO ADD NEW FILED INTO ENTITY CLASS
}

//return data

I hope it could explain the question :)

Thanks again.

Answer 1

You must create a new partial part of your entity class (in the new .cs file) and add new fields to that class. You must not modify the partial part created by autogeneration because autogenerated files will be overwritten every time you change EDMX file. You also must not include the field in EDMX because EDMX defines your mapping to database = it contains only fields in database.

Create a new file WebOrderPart.cs in the same assembly and namespace as your autogenerated classes containing:

public partial class Weborder
{
  public string newField1 {get; set;} 
  public string newField2 {get; set;} 
}

Answer 2

Dosn't [NotMapped] work.

 [NotMapped]
 public string newField1 {get; set;}

Answer 3

First of all, you shouldn't modify the data model file. This file represents your data.

Second, you shouldn't be returning your data model objects/collections from your Repository. This is a very bad practice because you are creating a dependency between the Controller/View and the Model. I suggest you create custom Model objects that contain the properties you need in your View, map your entities to those Model objects and only return Model objects or collections of Model objects from your Repository.