Parsing JSON POST data sent from Unity to Ruby On Rails - ruby-on-rails

Question

I'm building a Rails service for a Unity front end. One of the controllers is having an issue parsing the JSON blob from my UnityWebRequest. Here is what Unity says it is sending:
[StoryPost] Sending request to localhost:3000/stories/new with post data [words, {"_array":[{"_text":"mailing"}]}]
And here is what Rails is logging when it receives the JSON:
Started POST "/stories/new" for 127.0.0.1 at 2017-08-26 20:08:40 -0400
Error occurred while parsing request parameters.
Contents:
words=%7B%22_array%22%3A%5B%7B%22_text%22%3A%22mailing%22%7D%5D%7D
ActionDispatch::Http::Parameters::ParseError (743: unexpected token at 'words=%7B%22_array%22%3A%5B%7B%22_text%22%3A%22mailing%22%7D%5D%7D'):
actionpack (5.1.3) lib/action_dispatch/http/parameters.rb:113:in `rescue in parse_formatted_parameters'
actionpack (5.1.3) lib/action_dispatch/http/parameters.rb:107:in `parse_formatted_parameters'
It looks like I have some sort of encoding error. This started happening once I added the following code to my web request:
_request.SetRequestHeader("Content-Type", "application/json");
_request.SetRequestHeader("Accept", "application/json");
If I comment out the two SetRequestHeader calls mentioned above, then here is what Rails logs:
Started POST "/stories/new" for 127.0.0.1 at 2017-08-26 23:13:14 -0400
Processing by StoriesController#new as */*
Parameters: {"words"=>"{\"_array\":[{\"_text\":\"inspectors\"}]}"}
I added this code so that Rails would automatically know to parse my POST data as JSON. Anyone seen this type of issue before? New to Rails and HTTP, but not to Unity.
Relevant Code
For reference, here is my Rails Controller:
class StoriesController < ApplicationController
def new
post_data = params["words"]
words_array = post_data["_array"];
puts "words " + words_array
story = Story.new(words_array)
story.save()
end
end
And here is my Unity code. Note: _PostData is a Dictionary<string, string>.
protected ServiceCall()
{
switch (_Type)
{
case RequestType.Get:
_request = UnityWebRequest.Get(_URL);
break;
case RequestType.Post:
_request = UnityWebRequest.Post(_URL, _PostData);
break;
default:
throw new NullReferenceException("Unknown request type " + _Type);
}
_request.SetRequestHeader("Content-Type", "application/json");
_request.SetRequestHeader("Accept", "application/json");
_request.downloadHandler = new DownloadHandlerBuffer();
Diag.Crumb(this, $"Sending request to {_URL} with post data {_PostData.Pretty()}");
_requestOperation = _request.Send();
}
Here is how I am building _PostData
protected override Dictionary<string, string> _PostData
{
get
{
var asArray = new JsonArray<Word>(Luke.GuessWords);
string json = JsonUtility.ToJson(asArray);
return new Dictionary<string, string>{{"words", json}};
}
}
JSONArray is just a simple class that has an _array field, because Unity's JsonUtility cannot serialize top-level arrays.

Answer 1

In response to the feedback that my entire POST body was not formatted as JSON, I instead changed _PostData to return a string, and in my deriving classes serialized _PostData to JSON. Then in the base class, I encoded the JSON as bytes and sent it up as the POST body. Here is my changed code:
In Rails:
def new
words_array = params["_array"]
puts "words " + words_array.to_s
story = Story.new(words_array)
puts "story is " + story.to_s
end
In Unity:
protected override string _PostData
{
get
{
var asArray = new JsonArray<Word>(Luke.GuessWords);
string json = JsonUtility.ToJson(asArray);
return json;
}
}
And...
case RequestType.Post:
_request = UnityWebRequest.Post(_URL, new Dictionary<string, string>());
_request.uploadHandler = new UploadHandlerRaw
(
Encoding.UTF8.GetBytes(_PostData)
);
break;