Can I use powerautomate to stop a choice or selection field when the amount of choices exceeds a certain number ?

[Anonymous]

I want to invite for example 100 persons for day 1 and 100 persons for day 2. When the subscriptions for day 1 or day 2 are exceeding the 100, the choice of this day should be blocked with a message or just removed from the choice list. Is there someone who could give me a hint how to do this ?

I create a list with a field of the name of the person and then a simple selection field with the choices of the days.

[RobElliott]

Yes, using the "Send an HTTP request to SharePoint" action (more than once) it is possible to remove a choice option for a course when the number of people who have signed up reaches 100. I will post up screenshots of the flow shortly.

[RobElliott · Accepted solution]

@Anonymous ok the flow is as follows and it will remove the option from the SharePoint choices options when the number of people who have signed up is 3 or more (to take account of people signing up at exactly the same time). Yours will be 100 but I couldn't take the time to add that many items.

The initial SharePoint list has a Choice column for the course and there are 3 options: SharePoint, Power Apps and Forms. There are currently 2 signups each for SharePoint and Power Apps, nothing for Forms. We will add 1 more to SharePoint.

1. In the flow the trigger is the SharePoint "when an item is created" in the list named Course and the column is also named Course.

2. The first action is a SharePoint "send an http request to SharePoint" and the only thing you need in this is the Uri field which is _api/web/lists/GetByTitle('Course')/Fields/getbytitle('Course')

3. At this point add a terminate action and test the flow. 

 4. In the results of the flow click the output raw data link to open the panel below. You want to copy (ctrl+c) everything after "d": to (but including) the closing curly brackets after EditFormat

5. Next, add a Parse JSON action and click the Generate from Sample button. In the screen that appears paste in what you've just copied. Then in the Content field paste in the expression (making sure the name of the action is correct, you'll see mine is called Send an HTTP request to SharePoint 2 which yours might not be - it's just due to the order I did things in!

outputs('Send_an_HTTP_request_to_SharePoint_2')?['body']?['d']

6. Next, initialise an array variable called varAllCourses and for the value field select results from the Parse JSON section of the dynamic content box.

7. Initialize string variable called varCourse and set the value to Course Value selected from the dynamic content box. (it uses value because it's a choice column).

Next, add a Filter array action and in the From field select the varAllCourses from the variables section of the dynamic content box. Then in the left field select varCourse is not equal to  then in the right field add the expression item()

8. Add a set variable action and select varAllCourses and in the value field select Body from the filter array section of the dynamic content box.

Next, add an initialise variable action, set it to Float and leave the value empty.

9. Add a SharePoint get items action and set the filter query to Course eq '' and inside the single quotes select the varCourse variable. So we are only bringing back the course that the user has selected.

10. Add an Apply to each action and select value from the dynamic content box. Inside the apply to each add an increment variable action, select the varCount variable and set the value to 1. This will count however many of the currently selected course have been booked.

11. We now need a condition that looks at whether the varCount variable is greater than or equal to 3 (in your case 100).

12. The red if no channel can be left empty.

In the green if yes channel add a compose action and for the inputs select varAllCourses:

13. Finally, and still in the red if yes channel, add another send an http requeswt to SharePoint action as before but this time we need headers which are:

Accept - application/json;odata=verbose

Content-Type - application/json;odata=verbose

X-HTTP-Method - MERGE

Then the body field has the following with an expression for the outputs of the previous compose:

{'__metadata':
{ 'type': 'SP.FieldChoice' },
'Choices': { 'results': @{outputs('Compose')} }
}

14. When a new item is added to the list it will check if the current count (for SharePoint in my example) is 3 or more:

15. If it is it will remove that choice from the options, leaving those who have already selected it intact. The options for the user to select will now only be the other options and the option where the count is more than 3 (SharePoint in my case) will no longer be an option.

Hope that helps.

Rob
Los Gallardos
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