Invite to an event with limited spaces

SSime1980 Forms can't do this on its own but there are a couple of approaches you could take, both of which require 2 SharePoint lists, one for the details of the event and one for the registrations for each event.

1) When a response is submitted a flow in Power Automate gets the number of registrations for each event and if it's below the maximum attendees then it saves the response into the registrations list, increments the number registered for that event by 1 and sends a confirmation email to to the responder saying they have registered. If the number registered has already reached the maximum then an email goes back to the responder saying "sorry, the event is now full"

I used to use this approach but don't really like it now because it's not so good for the responder. When they submit the response they think they've registered don't know until a minute or so later hat the event is full. It doesn't create the best impression.But if the attendees include external people this is really the only option you have.

2) If your attendees are internal you could build a Power Apps app with the same 2 lists and you could either have people use it directly in the browser or have it embedded in a SharePoint page.. But in this case the app checks the maximum number of attendees and disables the "Register for this event" button if the maximum has been reached.

The events list is in a gallery down the left side. The user selects one of the event titles to see the details which are displayed in various containers and then if the number of attendees (shown as Reg in the screenshot) is less than than the  maximum (Max) then they click the button.

 You can see an example of this running in the attached video.

Come back if you have any questions or need more details about how this was built (it took about 2 hours in total).

Rob
Los Gallardos
Microsoft Power Automate Community Super User.
Principal Consultant, SharePoint and Power Platform WSP Global (and classic 1967 Morris Traveller driver)