ASP.NET MVC Entity Framework Id cannot be null

Question

When it comes to ASP Identity, I created a new table, custom table using code first and migration (code below). When I try to inset into that table using DbContext I have the id cannot be null error from entity framework. I tried using id with annotation as computed / identity and the error is the same.

For sure, I missed something but I cannot figure out what.

public class AspNetCountryTable
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public String Id { get; set; }
        public String CountryName { get; set; }
        public String CountryCode { get; set; }
    }

What I want to do is to have and automated generated Id (String) just the way asp identity is generating the id for the user.

Thanks!

Did you update your data base so that it actually generates an ID? — Fabiano, Jun 20 '17 at 08:26
@Fabiano I used add-migration "new_migration_name" and update-database from package console to generate (in theory) the new sql table. Was there something else to do? — Iosif Bancioiu, Jun 20 '17 at 08:28
Could you try with `[DatabaseGenerated(DatabaseGeneratedOption.None)]` instead of `[DatabaseGenerated(DatabaseGeneratedOption.Identity)]`? — Keyur PATEL, Jun 20 '17 at 08:33
String is a nullable type, hence it doesn't use computed values unlike `int` does when applying `DatabaseGeneratedOption.Identity` option. Try using `[DatabaseGenerated(DatabaseGeneratedOption.None)]` instead, or follow similar steps [here](https://stackoverflow.com/questions/36022901/how-can-i-change-an-int-id-column-to-guid-with-ef-migration) and [here](https://stackoverflow.com/questions/31926542/code-first-migration-from-int-to-guid-primary-key-issue) but instead of GUID it stores string. — Tetsuya Yamamoto, Jun 20 '17 at 08:33
What do expect SQL to generate an identity column from `string`? — mshwf, Jun 20 '17 at 08:39
did not work, changed at db level to uniqueidentifier and added addsequentialid() as default sql value — Iosif Bancioiu, Jun 20 '17 at 10:26

score 0 · Accepted Answer · answered Jun 20 '17 at 10:27

0

Had to add at SQL level Id column as uniqueidentifier instead of string and default sql value in migration script: newsequentialid()

answered Jun 20 '17 at 10:27

Iosif Bancioiu

193
16

ASP.NET MVC Entity Framework Id cannot be null

1 Answers1