HTTPoison request with authentication

Questions / Help
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1

Hello everyone,

I am trying to access a web page with some pictures in it, so that I can download the pictures and then do some fun things with them. Very much like this post here with the smoothies https://medium.com/@Julien_Corb/web-scraping-with-elixir-using-httpoison-and-floki-26ebaa03b076 .

The difference is, the access is gated behind a login screen → username and password. I am fairly new to all of this, so my rookie mistake was to just send a request to the link, which naturally returns to me a %HTTPoison.Response{} structure. The body of the response being the logging screen.

For some reason the documentation of Httpoison is lacking… or rather not helpful, as it is just “This is an existing function. It takes parameters.” There is no example for what I am trying to do, which I thought would be a very common thing. Should I go to Hackney to find proper documentation?

So my question is, Can I do this all in one go? - Send a request with the appropriate logging parameters and directly receiving the body / the images straight away. How? How do I know, where do I look for further help?

Much appreciated if somebody could help with this. Thank you in advance!

2

First of all you should inspect the login page and find the actual POST request that is done to the server when you input the username and password and press submit, you should be able to identify it in browser debug window → network tab, that is the request you want to use to login with a http client like HTTPoison.

The second part is a little bit more tricky, you need to save the session cookie that you get after successful login and use it in subsequent requests to protected routes, you can take some inspiration from here: Help with HTTPoison POST - #7 by Aetherus

PS: That might not be the best example as its filled with macro magic, what you are interested in are the following lines:

# Options sent to hackney for setting the request cookies
options = [hackney: [cookie: cookies]]]

# Example usage
headers = []
HTTPoison.get("my_url", headers, options)

# Extracting cookies from the response
defp cookies(%HTTPoison.Response{} = resp) do
    resp.headers
    |> Enum.filter(fn
      {"Set-Cookie", _} -> true
      _ -> false
    end)
    |> Enum.map(fn{_, cookie} -> cookie end)
  end
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