ASP.NET with Entity Framework: EF does not generate identity automatically

Question

I'm quite new to ASP and I'm creating a simple ASP.NET MVC App that stores personal info in a database. Using a DB First approach, I created the following db table:

CREATE TABLE [dbo].[Author] (
[PersonID]  INT           IDENTITY (1, 1) NOT NULL,
[MobileNum] NVARCHAR (50) NULL,
[Location]  NVARCHAR (50) NULL,
[LinkedIn]  NVARCHAR (50) NULL,
[FaceBook]  NVARCHAR (50) NULL,
[Picture]   IMAGE         NULL,
[Name]      NVARCHAR (50) NULL,
[Email]     NVARCHAR (50) NULL,
PRIMARY KEY CLUSTERED ([PersonID] ASC)

);

I use PersonID as a PrimaryKey and I want EF to autogenerate this for me, but for some reason this does not happen. I adjusted the identity options manually among the properties:

and I also attached the necessary attributes to my model (although I read somewhere that autogeneration is supposed to work without them as well):

public partial class Author
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int PersonID { get; set; }
    public string MobileNum { get; set; }
    public string Location { get; set; }
    public string LinkedIn { get; set; }
    public string FaceBook { get; set; }
    public byte[] Picture { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
}

Yet, the ModelState of the db is always false during the creation of a new entry:

and taking a closer look at it in the debugger, the problem seems to be that EF expects PersonID to be assigned by the user.

I have the following View belonging to the Create Action:

<div class="form-group">
    @Html.HiddenFor(model => model.PersonID, htmlAttributes: new { @class = "control-label col-md-2" })
</div>

Is there something else I'm supposed to do to enable the autogeneration of PersonIDs? What am I missing? Pointing me to a beginner level, DB First article is also much appreciated, since most articles I found did not make any mention of this problem whatsoever (e.g., here, here, or here).

It would be really great, if you could post your create table script instead of using a picture, so we can reproduce it more easily by just copy pasting everything in. — Marco
– Marco, Commented Feb 2, 2018 at 20:53
Code looks valid. What is the value of a.PersonID when you hit the post? You might want to consider using ViewModels with automapper. That cleans up a lot of these issues. — Steve Greene
– Steve Greene, Commented Feb 2, 2018 at 21:15
Marco: true, I update my post, @Lalithanand Barla: I have an int autoporperty and I started up with no annotations, so I have a different problem. — oneManArmin
– oneManArmin, Commented Feb 2, 2018 at 21:39
@SteveGreene: PersonID is 0, while my IdentitySeed is 1, so this is probably becuase of the default value of an int. — oneManArmin
– oneManArmin, Commented Feb 2, 2018 at 21:43

oneManArmin · Accepted Answer · 2018-02-03 15:59:48Z

Thank you for all your suggestions in the comment section, but surprisingly, the problem had nothing to do with the DB or the Model: I recreated the whole DB, but still got the same error. Turns out, the problem was in the view responsible for prompting input from the user upon creating a new entry, to be more specific, this was the problematic part:

<div class="form-group">
    @Html.HiddenFor(model => model.PersonID, htmlAttributes: new { @class = "control-label col-md-2" })
</div>

SOLUTION: I just deleted the whole <div> with the @Html.HiddenFor html helper for the id and the db now accepts new entries. Simple as that.

What I think caused the problem is that the db seemed to expect ID to be provided by the user even though the helper was set to hidden and I suppose, this is why ModelState.IsValid was always false. I used @Html.HiddenFor in the Edit feature (I wrote edit before create to test the db with mock data) and it had no problems, so I thought by disallowing the user to interact with a piece of data, ASP will automatically know not to expect it from the user, but clearly, I was wrong.

Rasitha Ariyarathna · Accepted Answer · 2018-02-03 03:58:16Z

0

Try this code to declare primary key

[PersonID] int IDENTITY(1,1) PRIMARY KEY

answered Feb 3, 2018 at 3:58

Rasitha Ariyarathna

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