Entity Framework Code first making a column non-nullable

Question

I am using EF code first for my project. I have following code in my DataModel

[HiddenInput(DisplayValue = false)]        
public DateTime? PasswordDate { get; s         


        

Answer 1

That's because you allowed NULL values in that column, then tried to make it non-nullable. It will subsequently try to migrate your existing data into that newly non-nullable column, which will break because you already have NULL values in there.

Two solutions:

1) Change it back to nullable
2) Give it a default value for items that don't have a value.

Answer 2

It's not possible to directly add a non-nullable column to a table that has historical data in the table if no default value is provided for that column.

What I do is

1. add the column as nullable.
2. provide an sql script to populate this newly added column.
3. alter the column to make is as non-nullable.

Code example(with postgres database):

 public override void Up()
    {            
        AddColumn("public.YourTableName", "YourColumnName", c => c.Int(nullable: true));
        Sql(@"UPDATE ""public"".""YourTableName""
              SET ""YourColumnName"" = Value you want to set
            ");

        AlterColumn("public.YourTableName", "YourColumnName", c => c.Int(nullable: false));
    }