catch_json_parse_errors.rb

module Middleware
  class CatchJsonParseErrors
    def initialize(app)
      @app = app
    end

    def call(env)
      @app.call(env)
    rescue ActionDispatch::Http::Parameters::ParseError => error
      if env['HTTP_ACCEPT'] =~ /application\/json/ || env['CONTENT_TYPE'] =~ /application\/json/
        error_output = "There was a problem in the JSON you submitted: #{error}"
        Rails.logger.debug(error_output)
        [
          400, { "Content-Type" => "application/json" },
          [{ :status => 400, :error => error_output }.to_json]
        ]
      else
        raise error
      end
    end
  end
end