Unique columns values in Entity Framework - Code First

Question

I have an entity like this:

public class User
{
    public string Name { get; set; }
    public string LastName { get; set; }
    public string Username { get; set; }   // this is an EmailAddress

    [Key]
    public Guid Id { get; set; }      
}

How can I define the Username to be unique too?

Using Entity Framework 6.1.3

score 3 · Accepted Answer · edited May 23 '17 at 11:45

3

If you’re using the newest EF (6.1+) then you can use this code:

[Index("UserNameIndex", IsUnique = true)]
[MaxLength(100)]
 public string UserName { get; set; }

With EF of earlier versions there’s more complex approach which you can check here: Unique key with EF code first

edited May 23 '17 at 11:45

Community

1
1

answered Jun 04 '16 at 22:00

Ivan Yurchenko

3,762
1
21
35

ty will try that immediately :D – Felix D. Jun 04 '16 at 22:01
I am getting this exception: "Column 'Username' in table 'dbo.Users' is of a type that is invalid for use as a key column in an index." – Felix D. Jun 04 '16 at 22:05
it seems to correspond to http://stackoverflow.com/a/23055838/4610605 can you help me out ? I don't get whats wrong .... – Felix D. Jun 04 '16 at 22:07
Try to add the MaxLength attribute. The Indexes length is limited so you have to specify the max length value for your property. – Ivan Yurchenko Jun 04 '16 at 22:08

Unique columns values in Entity Framework - Code First

1 Answers1