unable to add new record to a table with "auto increment" set using mvc

Question

Hello
I am trying to add a new record using class

    public partial class TP004Master
    {
        public int APP_ID { get; set; }
        public string Site_Coord_ID { get; set; }
        public string PTL_ID { get; set; }
        public string TTL_ID { get; set; }
        public string STL_ID { get; set; }
        public string Create_By { get; set; }
        public Nullable<System.DateTime> Created_on { get; set; }
        public string modified_By { get; set; }
        public Nullable<System.DateTime> modified_on { get; set; }
    }

In database , the APP_ID is a primary key and it is auto incremented.

//save into TP004Master
                TP004Master tp004Master = new TP004Master();

                tp004Master.Site_Coord_ID = Engs.Coord_ID;
                tp004Master.PTL_ID = Engs.PTL_ID;
                tp004Master.TTL_ID = Engs.TTL_ID;
                tp004Master.STL_ID = Engs.STL_ID;
                tp004Master.Create_By = "1";
                tp004Master.Created_on = DateTime.UtcNow.AddHours(3);

                DB.TP004Master.Add(tp004Master);
                DB.SaveChanges();

It throws this error :
"SqlException: Cannot insert explicit value for identity column in table 'TP004Master' when IDENTITY_INSERT is set to OFF."

when I debug, I find that the tp004Master.APP_ID get the value : 0
Though I didn't set it to any value any where.

Answer 1

Hi @خالد الريمي ,
It' s a EF problem not MVC.I think you need to add the [DatabaseGenerated(..)] annotation to indicate an IDENTITY column in the table.Just like this:

 [DatabaseGenerated(DatabaseGeneratedOption.Identity)]  

You need to either make sure the value in the object mapped to this column is not modified or marked as modified.
Best regards,
Yijing Sun

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