Handle views using Phoenix as a RESTful API app - rest

Question

I'm having trouble understanding how to handle phoenix views properly.
Let's say that a client is calling "login_user" api.
My controller will handle the request, checking if user is enabled to access or not. As response, i need to send user's data to the caller.
Now, after controller's login logic, what's the proper way to respond?
1) fetch all data needed by the caller inside the controller:
user_data = function_that_fetch_user_data()
conn
|> put_resp_header("content-type", "application/json")
|> put_status(:ok)
|> send_resp(Status.code(:ok), user_data)
2) render the view
conn
|> put_resp_header("content-type", "application/json")
|> put_status(:ok)
|> render(login.json, user)
and fetch data inside it
defmodule CryptomonitorWeb.UserView do
use MyAppWeb, :view
def render("login.json", user) do
token = generate_user_token(user.mail)
%{
token: token,
email: user.mail,
group: "operators"
}
end
end
Getting data and building my response directly in the controller is more clear and clean to me, but i want to know what's the "right" way to handle api responses. My app will usually just return json to the client and sometimes render some html page.

Answer 1

Views are representation of a data you want to send to as a response. So first you need to have some data, second you have to present it in the way it have to be presented in some API or an HTML page.
You are definitely don't want to go into a database from a view, but if you don't go there, then the border is more subtle.
Still, generate_user_token looks like a data emitter, not like a data presenter. And who knows, maybe one day someone will change the function, so it'll hit a database to generate token.
To avoid related troubles, better to have data generators out of a view. Place them into controller, then send results to a view.
So, I'm voting for option 1.