C#•4mo ago

How to create a foreign key pointing to the db table created by ASP.NET Identity (AspNetUsers)?

Hi! I'm making a house listings app for school, using the MVC pattern. Naturally, one of my main db tables is "HouseListings" and naturally one of the columns on that table is UserId and it's supposed to be based on a foreign key pointing to a user ID to associate that particular House Listing to the user that created it. What I wanted to do was avoid creating my own "Users" db table on top of the built in "AspNetUsers" one created automatically when I accepted the Identity schema, so I need to point to that in my HouseListings model class, but obviously AspNetUsers isn't in my Model. From my googling it seems that one can actually bring the Identity models explicitly into my project and work from there, but I don't think that would be necessary. Can I just do a dummy empty class in my Model? Like so:

public class User : IdentityUser
{
}

public class User : IdentityUser
{
}

Thus "bringing in" the AspNetUsers table into my Model and that way I can point to it in my "HouseListings" model class. Would this work? If not how can I make it work to do what I said?

9 Replies

Angius•4mo ago

You can just create a navigation property to IdentityUser

public class Whatever
{
    public IdentityUser Owner { get; set; }
}

public class Whatever
{
    public IdentityUser Owner { get; set; }
}

That said, inheriting from IdentityUser is something you'll have to do anyway, soon as you want to put anything else on the user

Gipper•4mo ago

Ok, so to make sure I understand. I now have this class in my project:

using Microsoft.AspNetCore.Identity;
using System.ComponentModel.DataAnnotations;

namespace MyNamespace
{
    [Keyless]
    public class IdentityOwner
    {
        public IdentityUser? IdentityUser { get; set; }
    }
}

using Microsoft.AspNetCore.Identity;
using System.ComponentModel.DataAnnotations;

namespace MyNamespace
{
    [Keyless]
    public class IdentityOwner
    {
        public IdentityUser? IdentityUser { get; set; }
    }
}

and in my HouseListings class, I now have:

namespace MyNamespace
{
    public class HouseListing
    {
        //other fields above
        [ForeignKey(nameof(IdentityOwner))]
        [Column("user_id")]
        public int UserId { get; set; }
        public IdentityOwner userIdentity {  get; set; }
    }
}

namespace MyNamespace
{
    public class HouseListing
    {
        //other fields above
        [ForeignKey(nameof(IdentityOwner))]
        [Column("user_id")]
        public int UserId { get; set; }
        public IdentityOwner userIdentity {  get; set; }
    }
}

Angius•4mo ago

Why? Scratch that IdentityOwner, it seems useless Just have

namespace MyNamespace
{
    public class HouseListing
    {
        //other fields above
        public int UserId { get; set; }
        public IdentityUser User {  get; set; }
    }
}

namespace MyNamespace
{
    public class HouseListing
    {
        //other fields above
        public int UserId { get; set; }
        public IdentityUser User {  get; set; }
    }
}

Gipper•4mo ago

The foreign key decoration is necessary tho right?

Angius•4mo ago

Not at all By convention, [Name]Id property is the foreign key to the table represented by [Name] property

Gipper•4mo ago

Then in your example, UserId is pointing to the Id of a User class I also have to have? Or just the User object created immediately below it?

Angius•4mo ago

There's no User class in my example Nor does the property create any objects IdentityUser is the base user type used by Identity This property references it Thus, creating a one-to-* relationship

Gipper•4mo ago

and by convention UserId will automatically point to the Users table created by Identity??

Angius•4mo ago

You would have to configure the exact relationship kind UserId will store the foreign key

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How to create a foreign key pointing to the db table created by ASP.NET Identity (AspNetUsers)?