Create an array of user

Hi everyone,

I must let the possibility to my users to subscribe to a list, then send them a notification. (I use notifications with oneignal). I need to retrieve at the end a user format array just like this [“user id 1”, “user id 2”, “user id 3”, “user id 4”….]
Then, I could retrieve this array, and pass it as a parameter of my request and therefore send a notification to all the users in this array.

Here is the typical userflow that I hope to have:

1 - The user clicks on “register”
2- his id is sent to my backend (for example id. n°314)
3- his id is added to all the other id’s [“12”, “678”, “33”, “90”, 314.]
4- I get this array and I make my request

I don’t know what kind of content to choose (JSON? Or repeatable components?)

Please feel free to tel me if I was not been clear
thank you.

So i create a JSON to a collection type and I did a custom route and a custom controller to push the value inside the request body into the array that I declare in the JSON. So now I can post notification to specific segment of users