I have a button on my form List A(CAR list) that allows to open new window and create a new item in List B (5why list) . I'm passing value Item ID (CARNumber) in the URL. And I can query this ID on my new item in List B using querystring function.
Question is how to prepopulate a lookup field that corresponds to the passed value itemID and how to auto check the box link to existing CAR.
The purpose is that when users click the button to create a 5WHY action they are taken to a new 5WHY form that is already linked to the CAR list. So they don't have to manually select it.
I know I am a bit late... did u already solved it by urself?
If not (and if I got it right u got the ID on the NewForm in List B):
U could set the Value (Example: 5) via JS in a textbox (that can be hidden somewhere on the form)
after that u could make a little JS function "if textbox isnt empty set the checkbox true" -- or you make a formula that is only activated when something is entered in the hidden textbox and then u could set the value with JS.
and u could link the 5 with a formula with a parselookup and a JS function to set the value.
Just an idea... bcs i dont know if u already solved it (so I didnt go into details).
If you only need the lookup to set itself maybe you could try the example in the following link:
under -Examples- the 2nd one: Automatic Option Selection