How to add unique non primary-key field to entity using Entity Framework 4.1?

Question

We are using Entity Framework 4.1 Code first.

We've got user entity with primary key set to UserId and need UserLogin to be unique. How can it be done?

possible duplicate of [Unique key with EF code first](http://stackoverflow.com/questions/5701608/unique-key-with-ef-code-first) — Ladislav Mrnka, Sep 05 '11 at 09:54

score 15 · Accepted Answer · edited Jan 21 '16 at 20:19

15

Entity Framework does not support Unique constraints. You can create them using a SQL Query to generate unique constrains when initializing the database. Write your custom initializer for the model and execute SQL command to generate constrain.

Edit

Now (EF 6.1 onwards )you can easily have unique constrains ,

[Index("UserLoginIndex", IsUnique = True)]
public string UserLogin { get; set; }

edited Jan 21 '16 at 20:19

Ehsan88

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answered Sep 05 '11 at 09:56

Jayantha Lal Sirisena

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As of EF 6.1 the `[Index(IsUnique = true)]` data annotation is available – calebboyd Apr 29 '14 at 15:45
Yeah it's not released yet though. – Jayantha Lal Sirisena Apr 30 '14 at 03:17
The [nuget](http://www.nuget.org/packages/EntityFramework/) package was released on 3/17/14.. – calebboyd Apr 30 '14 at 03:42

score 2 · Answer 2 · answered Sep 05 '11 at 09:53

2

Check out the unique constraints, I think that's what you're looking for?

http://weblogs.asp.net/manavi/archive/2011/01/23/associations-in-ef-code-first-ctp5-part-3-one-to-one-foreign-key-associations.aspx

answered Sep 05 '11 at 09:53

Smudge202

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That is answer pointing to non existing API. No EF version supports this yet. – Ladislav Mrnka Sep 05 '11 at 09:54
New link supported by CTP5 added, that any use? – Smudge202 Sep 05 '11 at 09:56

How to add unique non primary-key field to entity using Entity Framework 4.1?

2 Answers2