How to use [Index] attribute in Entity Framework 6.1.1 with Code First

Question

I'm using Entity Framework 6.1.1 and Code first. EF 6.1 should have added support for the Index attribute, but neither the editor auto-completion or compiler accept the [Index] attribute such as:

[Index]
public DateTime TimeOfSale { get; set; }

All project references point to the DLLs for EF 6.1.1.

I'm also running SQL Server Compact Edition 4.0.

How to enable the use of the new [Index] attribute?

Do you have the relevant using statement in the file with this code in? — DavidG
– DavidG, Commented Sep 25, 2014 at 16:29
Yes - I have using System.ComponentModel.DataAnnotations; , and the [Key] attribute is accepted. — Mike
– Mike, Commented Sep 25, 2014 at 16:31

DavidG · Accepted Answer · 2014-09-25 16:31:42Z

10

While the KeyAttribute is in the System.ComponentModel.DataAnnotations namespace, the IndexAttribute class is in the System.ComponentModel.DataAnnotations.Schema namespace. You are likely missing the following using statement:

using System.ComponentModel.DataAnnotations.Schema;

answered Sep 25, 2014 at 16:31

DavidG

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3 Comments

Meeting Attender Over a year ago

I have the same problem. Adding Schema with a using statement didn't help.

Anne Gunn Over a year ago

Worked perfectly for me. But I had already upgraded my package to 6.1.2. Note that the Visual Studio 2013 Community Edition uses 6.0.something out of the <virtual> box and you have to upgrade to the new version of EF before the Using will help.

Kake_Fisk Over a year ago

@MeetingAttender you may be on an older version of .Net. Try using Microsoft.EntityFrameworkCore;

Opsimath · Accepted Answer · 2017-08-18 16:16:30Z

4

Note if you are working in ASP.NET Core as of this writing the Index attribute is not supported. An alternative is nicely outlined in this SO post though: Asp.net Core Entity Framework cannot find IndexAttribute

answered Aug 18, 2017 at 16:16

Opsimath

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