Getting error parsing List in map with Poison in elixir

Question

I am trying to parse an api query but I get an error in the following code:

apiUrl = "https://api.trivia.willfry.co.uk/questions?limit=1"
HTTPoison.start()
{:ok, req} = HTTPoison.get(apiUrl)

# Parses the request.
json = Poison.decode!(req.body)
parsed = Map.fetch!(json, :root)

The error says:

(BadMapError) expected a map, got: [%{"category" => "Film and TV", "correctAnswer" => "\"A martini. Shaken, not stirred.\"", "id" => 29312, "incorrectAnswers" => ["\"Elementary, my dear Watson.\"", "\"Carpe diem. Seize the day, boys. Make your lives extraordinary.\"", "\"Go ahead, make my day.\"", "\"I am a golden god!\"", "\"Toga! Toga!\"", "\"We rob banks.\"", "\"E.T. phone home.\"", "\"Here's Johnny!\"", "\"Made it, Ma! Top of the world!\"", "\"I have always depended on the kindness of strangers.\""], "question" => "Which of these quotes is from the film 'Goldfinger'?", "type" => "Multiple Choice"}]   
:erlang.map_get(:root, [%{"category" => "Film and TV", "correctAnswer" => "\"A martini. Shaken, not stirred.\"", "id" => 29312, "incorrectAnswers" => ["\"Elementary, my dear Watson.\"", "\"Carpe diem. Seize the day, boys. Make your lives extraordinary.\"", "\"Go ahead, make my day.\"", "\"I am a golden god!\"", "\"Toga! Toga!\"", "\"We rob banks.\"", "\"E.T. phone home.\"", "\"Here's Johnny!\"", "\"Made it, Ma! Top of the world!\"", "\"I have always depended on the kindness of strangers.\""], "question" => "Which of these quotes is from the film 'Goldfinger'?", "type" => "Multiple Choice"}])
(triv 0.1.0) lib/mix/tasks/request.ex:15: Mix.Tasks.Request.run/1
(mix 1.13.3) lib/mix/task.ex:397: anonymous fn/3 in Mix.Task.run_task/3
(mix 1.13.3) lib/mix/cli.ex:84: Mix.CLI.run_task/2

I am running this code from a module which implements the Mix.Task behaviour.

Please share the output of `IO.inspect(req.body)`. – Aleksei Matiushkin Feb 11 '22 at 15:20 — Aleksei Matiushkin, Feb 11 '22 at 15:20

score 0 · Accepted Answer · answered Feb 11 '22 at 16:07

Your parsed JSON appears to be a list, not a map:

[
  %{
    "category" => "Film and TV",
    "correctAnswer" => "\"A martini. Shaken, not stirred.\"",
    "id" => 29312,
    "incorrectAnswers" => ["\"Elementary, my dear Watson.\"",
     "\"Carpe diem. Seize the day, boys. Make your lives extraordinary.\"",
     "\"Go ahead, make my day.\"", "\"I am a golden god!\"", "\"Toga! Toga!\"",
     "\"We rob banks.\"", "\"E.T. phone home.\"", "\"Here's Johnny!\"",
     "\"Made it, Ma! Top of the world!\"",
     "\"I have always depended on the kindness of strangers.\""],
    "question" => "Which of these quotes is from the film 'Goldfinger'?",
    "type" => "Multiple Choice"
  }
]

When you try calling Map.fetch!/2 on it, you're getting an exception because it's a list, not a map.

This seems to be it, on te webiste of the api there was only one list but I think the json or http module added a extra list somewhere, thanks for the help! — Rik Smits, Feb 11 '22 at 17:46

Getting error parsing List in map with Poison in elixir

1 Answers1