Handling Invalid JSON Error in Rails 

Hi Friends,
Sometimes by mistake, when we send an incorrect JSON to server, the server is not able of handle the improper JSON so it throws an error, and the client doesn't get any proper error message. Today I am going to tell you how we can handle that.
If you try to handle the json parse errors inside controller, you won't be able to do that because, parsing of the JSON is done in middleware ActionDispatch::ParamsParser, that throws an exception before the controller comes into picture. So we need to handle it, before it reaches to controller, In Rails we can do this using the rake middleware. For handling the json parse error you need to create a middleware file like this:

## app/middleware/handle_incorrect_json.rb

class HandleIncorrectJson
  def initialize(app)
    @app = app
  end

  def call(env)
    begin
      @app.call(env)
    rescue ActionDispatch::ParamsParser::ParseError => e
      if env['HTTP_ACCEPT'] =~ /application\/json/
        return [
          400, 
          { "Content-Type" => "application/json" },
          [ { status: 400, error_message: "The JSON you sent has this error:
          	#{e}" }.to_json 
          ]
        ]
      else
        raise e
      end
    end
  end
end

Now at last you need to insert the middleware before the ActionDispatch::ParamsParser inside config/application.rb

## config/application.rb
module AppName
  class Application < Rails::Application
 		...........................
 		...........................
    config.middleware.insert_before ActionDispatch::ParamsParser, "HandleIncorrectJson"
    ...........................
    ...........................
  end
end

Now from now your application will deal all kind of improper json formatting errors in your way. Hope you liked reading this.