ADO.NET Entity Connection String for Multiple Projects

I suggest a slight variation on the suggestions given above.

It's not a huge improvement, but at least it gives you some separation of concerns.

When the EF wizard creates the .edmx file and its associated .Designer.cs file, the C# code declares a partial class. So you can simply add another.cs file to the project containing the two EDM files.

This new file defines an additional static function for the same namespace and class.

This new static function will return an instance of the desired type (the descendant of ObjectContext).

The new file is a separate file, so it won't be overwritten if you re-create the .edmx and .Designer.cs.

You copy and paste the connection string from the .config of the EDM project, which is kind of a hack, but at least it keeps the connection string hidden in the EDM project.

The new file looks like this:

namespace MyNamespace
{
  public partial class MyEntities : ObjectContext
  {
    public static MyEntities New_MyEntities()
    {
      string connStr;
      MyEntities theContext;

      connStr = "metadata=res://*/MyClass.csdl|res://*/MyClass.ssdl|res://*/MyClass.msl;provider=System.Data.SqlClient;provider connection string=\"Data Source=localhost\\SQLSERVER;Initial Catalog=MyDb;Integrated Security=True;MultipleActiveResultSets=True\"";
      // set the connection string

      theContext = new MyEntities(connStr);
      // allocate it

      return theContext;
      // return it
    }
  }
}

To get a new entities object, you simply call the static function New_MyEntities() from your calling project.