CODEWITHSUNDEEP
ruby-on-railsjson
davidgyoung
davidgyoung

Reputation: 64941

Overriding the default Content-Type

I have a Rails API which accepts only JSON as input. If I fail to include a header of Content-Type: application/json, then request.headers['Content-Type'] defaults to application/x-www-form-urlencoded and the params do not get parsed properly. The whole json body becomes a key in the params. The result is a 422, which is confusing to API users.

How can I change this to default to parsing as json if no Content-Type header is supplied?

Lots of other questions answer how to do this with the response format. To change this default, you can specify it in the controller with:

 request.format = :json

Or in a route namespace with something like:

 namespace :api, defaults: {format: :json} do

This, however, changes the default response format and does not change the default request format. What I need to do is to change the default request format for parsing parameters.

Upvotes: 4

Views: 3781

Answers (3)

equivalent8
equivalent8

Reputation: 14227

I've solved it with middleware this way for Rails API (rails new my_project --api)

config:

# config/application.rb
# ...
require './lib/middleware/consider_all_request_json_middleware'
# ...

module MyApplication
    # ...
  class Application < Rails::Application
        # ...
        config.middleware.insert_before(ActionDispatch::Static,ConsiderAllRequestJsonMiddleware)
        # ...

middleware:

# lib/middleware/consider_all_request_json_middleware.rb
class ConsiderAllRequestJsonMiddleware
  def initialize app
    @app = app
  end

  def call(env)
    if env["CONTENT_TYPE"] == 'application/x-www-form-urlencoded'
      env["CONTENT_TYPE"] = 'application/json'
    end
    @app.call(env)
  end
end

original: https://blog.eq8.eu/til/content-type-applicationjson-by-default-in-rails-5.html

Upvotes: 3

davidgyoung
davidgyoung

Reputation: 64941

Here is my admittedly terrible solution derived from the suggestion in Micael Nussbaumer's answer. I'd love it if some Rubyists could magically turn this ugly hack into a pithy one liner.

module Api
  class BaseApiController < ActionController::API

  private
    # This is an ugly hack needed to make it default to json if you do not
    # specify a Content-Type.  If you see this and know of a better way please
    # say so!
    def params
      if !@params
        if request.headers["Content-Type"]=="application/x-www-form-urlencoded"
          body_string = request.body.read
          begin
            hash = JSON.parse(body_string)
            @params = ActionController::Parameters.new(hash)
          rescue
            # do nothing
          end
        end
        if !@params
          @params = super
        end
      end
      @params
    end

    ...

end

Upvotes: 3

m3characters
m3characters

Reputation: 2290

parsed = JSON.parse(json_body) unless request.headers["Content-Type"] == 'application/json'

Upvotes: 2

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