c# - Creating string index with Code first

Question

I'm using Entity Framework 6.1 code-first and my domain model is below.

class Item
{
    [Index]
    public string CreatedBy { set; get; }
} 

When I use update-database for migration, I get the following error. However as far as I researched [Index] should work as annotation to string.

Column 'CreatedBy' in table 'dbo.Items' is of a type that is invalid for use as a key column in an index.

question from:https://stackoverflow.com/questions/27687080/creating-string-index-with-code-first

Answer 1

Usually you get this error when you use a VARCHAR(Max) try using:

[Column(TypeName = "VARCHAR")]
[StringLength(n)]
[Index]
public string CreatedBy { set; get; }

where n is between 1 and 450.