Need Help Rails 3.2.3 -Pre-populating User data into simple_form for book resource passed into gmaps4rails to render marker into map.
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thanks for reading, I need help;

scenario: User registers onto website, entering in their "address" ex. San Francisco, CA -gmaps4rails then does it's magic & it shows in the user profile show view -user location -San Francisco.  {Not displaying map here}

Displaying map on book show.
User can upload a book -I'm using Simple_form {do I add a hidden field here with @user.address? -sorry confused, did this & it didn't work.}

So then if I put in the show view Location <%= @book.user.address %> -it shows San Francisco.

But, on the map below -nothing shows up.

How do I get the 2 to interlink?  So that people don't have to spend time filling in their location, if it's already associated with their account? 
Do I have to render an association for user address & book address for simple_form, but then how do I make that work correctly in the gmaps4rails.

Also, was looking at people using JS to render the marker, would you recommend that?
I'd like to use purely server-side though -as I want to use Ajax to submit the book form & display in an index with maybe hover over to display the map.  

Looking forward to your responses, as I've been stuck on it.  