Validate Unique Value in MVC5 and EF6

Question

In my MVC application I have a requirement where I want user to insert Unique value in a column.

i.e.: Username should be unique in Users table.

I used [Indes(IsUnique = true)] data annotation in my model.

But when I insert duplicate value in the field it throws an exception, but I want to display an Error Message on my View saying Please try with a different Username

Please help me what should I do here?

Possible duplicate: http://stackoverflow.com/q/29421572/861716 — Gert Arnold, Apr 13 '15 at 08:45
Yes, it is almost similar to what you linked, but how can I achive this. Should I validate it implicitly in my business layer or is there any default functionality to do this. — Harsh Sharma, Apr 13 '15 at 09:01

score 2 · Answer 1 · edited Apr 13 '15 at 13:31

You can use one of those:

Write your CustomValidator (ny recommendation)

[CustomRemoteValidator(ErrorMessage = @"Username already in use")]
public string Username{ get; set; }`

And override IsValid method

public override bool IsValid(object value)
{
    return !(this.DbContext.Set<User>().Any(a => 
        a.Username.Equals((string)value));
}

Check it in your business layer.
Check it before save entity in database by overriding SaveChanges() method.

Validate Unique Value in MVC5 and EF6

1 Answers1