How to search the picked element of a list in another list


I have two lists, one with all the elements and another one with just a few elements of the first list. What I’m trying to do is find the position of the selected item of the second list in the first list. The first list is a data base that has 1000 elements.


When I pass it to the screen1, It says that the index is smaller than 1 and doesn’t work. Can somebody give me an advice? Thanks in advance!!

Try like this:

see revised version…

It doesn’t work since I’m working with json, there’s another way to do it?

Boths lists are json ?

Please show examples of your json lists