So, the key method of invitation to a private beta is that you mail someone a code allowing them access to the system, for these purposes, let’s just assume that the code is some reasonably long unique string (in my code, it’s actually a uuid.) So, set up a migration something like this to manage them:

  def self.up
    create_table :invites do |t|
# deleted stuff
      t.string :guid
      t.integer :used_yet
# deleted stuff
    end
  end

used_yet isn’t a boolean for reasons that are too laborious to go into here, but reflect some functionality in the code that I’m not going to display. Assuming that you’re using acts_as_authentication and are redirecting anyone who tries to access your app to the default welcome page according to the usual methods, set up something like this in your routes.rb:

  map.root :controller => "welcome"

This is probably the case in like half the rails apps out there. Have the index method of the welcome controller put up a form with a field like:

#let's see if the formatter can handle rails erb without exploding.
< % form_tag('welcome/checkinvite', :method=>:get) do -%>
  < %= text_field_tag 'invite' %>
  < %= submit_tag 'begin' %>
< % end -%>

This lets the user enter their invite in more or less the normal method. Now in your ‘welcome’ controller, you’ll need a ‘checkinvite’ method that looks something like the following:

 def checkinvite
    @inviteguid = params[:invite]
    @invite = Invite.find_by_guid(@inviteguid)
    if(@invite == nil)
      flash[:notice] = "Your invite was invalid"
      redirect_to root_url
      return
    end
    if(@invite.used_yet == 1)
      flash[:notice] = "Your invite had already been used"
      redirect_to root_url
      return
    end
  end

After this, you’ll need to have some code in your HTML page that links you to the account/signup functionality of acts_as_authenticated. I’m not going to include that because I’m too lazy to fish it out of my app functionality, but you can do that pretty much with a link_to using :invite=%gt;@invite_guid as an extra parameter.

You need to put the same invite detection code in account/signup, and then when you’ve created the account, set invite.used_yet = 1. This is about as simple as a method that I can think of for doing the private beta functionality that seems to be so much in vogue these days. Enjoy.

I think the single most useful thing I’ve figured out recently in programming for MacOSX and the iPhone is this little snippet right here.

- (void) updateListForEntityNamed:(NSString*) entityName andSearchString:(NSString*) queryString
{
[...]
 
	MyDocument* current = [[NSDocumentController sharedDocumentController] currentDocument];
	if(current && current != self)
	{
		NSLog(@"CurrentDocument:%@ != self:%@", current, self);
		[current updateListForEntityNamed: entityName andSearchString: queryString];
		return;
	}
[...]
}

What this does is intercept incoming messages that are supposed to go to the current window, and redirect them to that instance. I’ve run into issues in Leopard (MacOSX 10.5) where this is an issue. To some extent, this is probably a misconfiguration in interface builder somewhere, but it also an issue when using CoreData, because the ManagedObjectContexts are particular to instances of NSManagedDocument, and there are issues that arise if you end up using the wrong context.

I am slowly becoming a great fan of CoreData, it’s a great persistence/object-graph-management layer. More on this later.