In case you are wondering the form post data is not being processed by server side in Flask framework, then you are definitely in the right place. Sadly, its very subtle in the flask documentation and I wasted considerable amount of time for such a trivial issue.
Server side Flask Code is :
Simple form submission was giving me 400 Bad request and much to my chagrin, I see a simple curl call giving me the desired result .. . .
So what went wrong ? apparently I had forgotten to set input name for my form elements and Flask uses input name instead of id which I feel is kinda weird.. anyways.. that solved the problem for me. Hope fully no more surprises in flask.