How to pass a URL parameter to FormPage?

I’m trying to pass a parameter on a FormPage. I know that passing parameters on a APIFunction works, like:

https://wolframcloud.com/...?x=5&y=10 

But, I see no way of doing this in a FormPage, is there anyway I can pass the parameter to the FormPage‘s fields?

https://wolframcloud.com/...?id=myId