Your create function is not matching the parameters that you are sending via curl. A possible fix is to change the first line from:
def create(conn, %{"user" => user_params}) do
to:
def create(conn, %{"accounts" => user_params}) do
Although personally i prefer to do little to no matching in controller function heads because I find the no function clause matching not very informative. If you changed your create to function to:
def create(conn, params) do
%{"user" => user_params} = params
...
end
Then you would have gotten a more informative pattern matching error.
