如何有效率地檢索.NET Core 2.1身分使用者及其關聯角色？

public class ApplicationUser : IdentityUser
{
    public ICollection<ApplicationUserRole> UserRoles { get; set; }
}

public class ApplicationUserRole : IdentityUserRole<string>
{
    public virtual ApplicationUser User { get; set; }
    public virtual ApplicationRole Role { get; set; }
}

public class ApplicationRole : IdentityRole
{
    public ICollection<ApplicationUserRole> UserRoles { get; set; }
}

public class ApplicationDbContext
    : IdentityDbContext<ApplicationUser, ApplicationRole, string, IdentityUserClaim<string>,
    ApplicationUserRole, IdentityUserLogin<string>,
    IdentityRoleClaim<string>, IdentityUserToken<string>>
{
    public DbSet<ApplicationUserRole> UserRoles { get; set; }

    // migrations omitted for brevity
}

services.AddIdentity<ApplicationUser, ApplicationRole>(options => options.Stores.MaxLengthForKeys = 128)
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddDefaultTokenProviders();

this.Users = userManager.Users.Include(u => u.UserRoles).ThenInclude(ur => ur.Role).ToList();