Question

I am using Entity Framework 4, and I am getting this error:

A foreign key value cannot be inserted because a corresponding primary
key value does not exist. [ Foreign key constraint name =
FK_Table1_Table2_ColumnId ]

Where Table1 is in one DBContext:

public class Database1DB : DbContext
{
   public DbSet<Table1> TableOne { get; set; }
}

and Table 2 is in another DBContext:

public class Database2DB : DbContext
{
   public DbSet<Table2> TabeTwo {get;set;}
}

Table 1 has a foreign key reference to Table2‘s column like this:

public class Table1
{
   [Key]
   public int Id {get;set;}

   [ForeignKey("Table2")
   public int ColumnId {get;set;}

   public virtual Table2 Table2 {get;set;}
}

public class Table2
{
   [Key]
   public int Id {get;set;}
}

Answer 1

You cannot model relations between entities defined in different contexts. Related entities must be in the same context to make it work. In your case you can simply use:

public class Table1
{
   [Key]
   public int Id {get;set;}
   public int ColumnId {get;set;}
}

public class Table2
{
   [Key]
   public int Id {get;set;}
}

And you will have to handle relation manually.