James James - 2 months ago 13
ASP.NET (C#) Question

Why does this violate the type constraint?

I'm trying to customise ASP.NET Identity 3 so that it uses integer keys:

public class ApplicationUserLogin : IdentityUserLogin<int> { }
public class ApplicationUserRole : IdentityUserRole<int> { }
public class ApplicationUserClaim : IdentityUserClaim<int> { }

public sealed class ApplicationRole : IdentityRole<int>
{
public ApplicationRole() { }
public ApplicationRole(string name) { Name = name; }
}

public class ApplicationUserStore : UserStore<ApplicationUser, ApplicationRole, ApplicationDbContext, int>
{
public ApplicationUserStore(ApplicationDbContext context) : base(context) { }
}

public class ApplicationRoleStore : RoleStore<ApplicationRole, ApplicationDbContext, int>
{
public ApplicationRoleStore(ApplicationDbContext context) : base(context) { }
}

public class ApplicationUser : IdentityUser<int>
{
}

public sealed class ApplicationDbContext : IdentityDbContext<ApplicationUser, ApplicationRole, int>
{
private static bool _created;

public ApplicationDbContext()
{
// Create the database and schema if it doesn't exist
if (!_created) {
Database.AsRelational().Create();
Database.AsRelational().CreateTables();
_created = true;
}
}
}


This compiles okay, but then throws a runtime error:


System.TypeLoadException

GenericArguments[0], 'TeacherPlanner.Models.ApplicationUser', on 'Microsoft.AspNet.Identity.EntityFramework.UserStore`4[TUser,TRole,TContext,TKey]' violates the constraint of type parameter 'TUser'.


The signature for
UserStore
is:

public class UserStore<TUser, TRole, TContext, TKey>
where TUser : Microsoft.AspNet.Identity.EntityFramework.IdentityUser<TKey>
where TRole : Microsoft.AspNet.Identity.EntityFramework.IdentityRole<TKey>
where TContext : Microsoft.Data.Entity.DbContext
where TKey : System.IEquatable<TKey>


ApplicationUser
is precisely an
IdentityUser<int>
. Isn't this what it's looking for?

Answer

Ran into this problem. It was crashing on the startup.cs file. changed

services.AddIdentity<ApplicationUser, ApplicationIdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>()
                .AddDefaultTokenProviders();

to

services.AddIdentity<ApplicationUser, ApplicationIdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext,int>()
                .AddDefaultTokenProviders();

declaring the key type seemed to get past the crash

Comments