How to modify the default AspNetUsers table in ASP.NET Core 6.0 MVC?

Here is the detailed steps for you. In my sample, I am using DBContext and MVCUser.

1. MVCUser, add <int> like below.

public class MVCUser : IdentityUser<int>
{
}

2. DBContext

using ASPNETCore6MVC.Areas.Identity.Data;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

namespace ASPNETCore6MVC.Areas.Identity.Data;

public class DBContext : IdentityDbContext<MVCUser, IdentityRole<int>, int>
{
    public DBContext(DbContextOptions<DBContext> options)
        : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);
        // Customize the ASP.NET Identity model and override the defaults if needed.
        // For example, you can rename the ASP.NET Identity table names and more.
        // Add your customizations after calling base.OnModelCreating(builder);
        
        // Rename Table
        builder.Entity<MVCUser>(entity =>
        {
            entity.ToTable("CompanyUsers");
            entity.Property(e => e.Id).HasColumnName("CompanyID");
        });

        builder.Entity<IdentityRole<int>>(entity => entity.ToTable("Roles"));
        builder.Entity<IdentityUserRole<int>>(entity => entity.ToTable("UserRoles"));
        builder.Entity<IdentityUserClaim<int>>(entity => entity.ToTable("UserClaims"));
        builder.Entity<IdentityUserLogin<int>>(entity => entity.ToTable("UserLogins"));
        builder.Entity<IdentityUserToken<int>>(entity => entity.ToTable("UserTokens"));
        builder.Entity<IdentityRoleClaim<int>>(entity => entity.ToTable("RoleClaims"));
    }
}

3. Program.cs

// Add services to the container.
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection") ?? throw new InvalidOperationException("Connection string 'DefaultConnection' not found.");
builder.Services.AddDbContext<DBContext>(options =>
            options.UseSqlServer(connectionString));
builder.Services.AddDatabaseDeveloperPageExceptionFilter();

//builder.Services.AddDefaultIdentity<MVCUser>(options => options.SignIn.RequireConfirmedAccount = true)
//    .AddEntityFrameworkStores<DBContext>();

builder.Services.AddIdentity<MVCUser, IdentityRole<int>>().AddEntityFrameworkStores<DBContext>().AddDefaultTokenProviders();

4. Backup your current database, or change the dbname in connectionString.

If not doing this, we may face To change the IDENTITY property of a column, the column needs to be dropped and recreated error.

5. Then we can restore the data from backup db.

The steps 4 is necessary, if the table name and structure are changed and there is already a lot of data, the previous data will affect the migration, so it is best not to change the table structure during later migration.

Test Result