title: Convert string representation of an array of json objects to map Elixir
body: <p>Here I have a payload coming to my controller action endpoint:</p>
  
  <pre><code>%{      
    "mandrill_events" =&gt; "[{\"event\":\"send\",\"msg\":{\"ts\":1365109999,\"subject\":\"This an example webhook message\",\"email\":\"example.webhook@mandrillapp.com\",\"sender\":\"example.sender@mandrillapp.com\",\"tags\":[\"webhook-example\"],\"opens\":[],\"clicks\":[],\"state\":\"sent\",\"metadata\":{\"user_id\":111},\"_id\":\"exampleaaaaaaaaaaaaaaaaaaaaaaaaa\",\"_version\":\"exampleaaaaaaaaaaaaaaa\"},\"_id\":\"exampleaaaaaaaaaaaaaaaaaaaaaaaaa\",\"ts\":1518203456},{\"event\":\"send\",\"msg\":{\"ts\":1365109999,\"subject\":\"This an example webhook message\",\"email\":\"example.webhook@mandrillapp.com\",\"sender\":\"example.sender@mandrillapp.com\",\"tags\":[\"webhook-example\"],\"opens\":[],\"clicks\":[],\"state\":\"sent\",\"metadata\":{\"user_id\":111},\"_id\":\"exampleaaaaaaaaaaaaaaaaaaaaaaaaa1\",\"_version\":\"exampleaaaaaaaaaaaaaaa\"},\"_id\":\"exampleaaaaaaaaaaaaaaaaaaaaaaaaa1\",\"ts\":1518203456}]"
  }
  </code></pre>
  
  <p>I am trying to decode the content of <code>mandrill_events</code>, so that I can then access some values, but I think the bracket is throwing it off.</p>
  
  <pre><code>get_in(payload, ["mandrill_events"]) |&gt; Base.url_decode64 |&gt; Poison.decode!
  </code></pre>
  
  <p>But that didn't work either.</p>
  
  <pre><code>** (ArgumentError) argument error
      :erlang.iolist_to_binary(:error)
      (poison) lib/poison/parser.ex:35: Poison.Parser.parse/2
      (poison) lib/poison/parser.ex:51: Poison.Parser.parse!/2
      (poison) lib/poison.ex:83: Poison.decode!/2
      (stdlib) erl_eval.erl:670: :erl_eval.do_apply/6
      (iex) lib/iex/evaluator.ex:250: IEx.Evaluator.handle_eval/5
      (iex) lib/iex/evaluator.ex:230: IEx.Evaluator.do_eval/3
      (iex) lib/iex/evaluator.ex:208: IEx.Evaluator.eval/3
      (iex) lib/iex/evaluator.ex:94: IEx.Evaluator.loop/1
      (iex) lib/iex/evaluator.ex:24: IEx.Evaluator.init/4
  </code></pre>