else_reaches_always_evenif_ifstatementissatified

@app.route('/create',methods=['POST'])
def create():
    print "create called"
    data_rec = {'username' : request.json['username'], 'password' : request.json['password']}
    users = [i.serialize['username'] for i in session.query(UsersLoginInfo).all()]
    print users, data_rec['username']
    if data_rec['username'] in users: #check account exists
        account_exists=True
        msg="An account with that username already exists, please choose another username."
        #return jsonify({'account_exists' : account_exists ,"msg": msg})
    else:
        account_exists=False
        id=len(users)
        user = UsersLoginInfo(username = unicode(data_rec['username']), password = unicode(data_rec['password']), id = id)
        session.add(user)
        session.commit()
        msg="Your account has been created. Please login with it."
        return jsonify({'account_exists' : account_exists ,"msg": msg})


Error:
127.0.0.1 - - [04/Mar/2016 05:41:41] "POST /create HTTP/1.1" 500 -
Traceback (most recent call last):
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "C:\Anaconda\lib\site-packages\flask\app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "C:\Users\sony\Dropbox\notepad_app\note_app_server\home.py", line 38, in create
    session.add(user)
UnboundLocalError: local variable 'user' referenced before assignment