Gated creation of entities (Users etc) depending on existing count in the database MVC5

Question

I have an application where an Administrator can create new users. New users can only be created if existing user count is less than what is allowed to the administrator (value set in the database in the account table)

Now i can easily just create an action filter checking the existing users count and depending on it, return an HttPStatusCodeResult for Bad request, or UnAuthorizedResult.

But what i want is that the "Create Button" should be disabled too. The create button is on the Index view. I can also do this by creating a custom html helper that renders the button as disabled depending on the count of existing users from the database.

But further on, I have other Entity Creation that needs to be gated depending on the count of existing entities in the database.

I would want to figure out a standard way of doing this accross the application, rather than create a seperate ActionLink helper and a seperate ActionFilter for each requirement.

Any pointers will be much appreciated.

Thanks

Answer 1

What you can do is setup a role for the ability to create users and remove it when they have created too many. Whenever they create a user, check to see if they meet the threshold, if they do, remove this privilege from their account. The code would be something like this...

[HttpPost]
[Authorize(Roles="CanCreateUsers")]
public ActionResult CreateUser(User u){
    var currentUser = GetCurrentUser(User.Identity.GetUserId());
    if(currentUser.UsersCreated >= 5){
        UserManager.RemoveFromRoleAsync(currentUser.UserID, "CanCreateUsers");
        //Probably want to refresh their cookies to refresh their roles too
    }

    UserManager.CreateAsync(u);
}

Then checking to see if a user can create users is as simple as checking their role

@if(User.IsInRole("CanCreateUsers"))
{
    <a>Create User</a>
}