```ruby
require 'rails/railtie'

module Transit
  module Rails
    class Railtie < ::Rails::Railtie
      config.before_initialize do
        require 'transit/rails/renderer'
        require 'action_controller/metal/renderers'

        Mime::Type.register "application/transit+json", :transit
        Mime::Type.register_alias "application/transit+json", :transit_verbose
        Mime::Type.register "application/transit+msgpack", :transit_msgpack

      end

      config.after_initialize do
        ActionController.add_renderer :transit do |obj, options|
          Transit::Rails::Renderer.new(obj, options).render
        end
      end

      initializer "transit.configure_rails_initialization" do |app|
        require 'transit/rails/reader'
        parameter_parsers = { Mime[:TRANSIT] => Transit::Rails::Reader.make_reader(:json),
                              Mime[:TRANSIT_MSGPACK] => Transit::Rails::Reader.make_reader(:msgpack) }
        if ActionDispatch::Request.respond_to?(:parameter_parsers=)
          ActionDispatch::Request.parameter_parsers = (ActionDispatch::Request.parameter_parsers || {}).merge(parameter_parsers)
        else
          app.middleware.swap("ActionDispatch::ParamsParser",
                              "ActionDispatch::ParamsParser", parameter_parsers)
        end
      end
    end
  end
end
```

Access MIME types by correct keys
user
```ruby
require 'rails/railtie'

module Transit
  module Rails
    class Railtie < ::Rails::Railtie
      config.before_initialize do
        require 'transit/rails/renderer'
        require 'action_controller/metal/renderers'

        Mime::Type.register "application/transit+json", :transit
        Mime::Type.register_alias "application/transit+json", :transit_verbose
        Mime::Type.register "application/transit+msgpack", :transit_msgpack

      end

      config.after_initialize do
        ActionController.add_renderer :transit do |obj, options|
          Transit::Rails::Renderer.new(obj, options).render
        end
      end

      initializer "transit.configure_rails_initialization" do |app|
        require 'transit/rails/reader'
        parameter_parsers = { Mime[:transit] => Transit::Rails::Reader.make_reader(:json),
                              Mime[:transit_msgpack] => Transit::Rails::Reader.make_reader(:msgpack) }
        if ActionDispatch::Request.respond_to?(:parameter_parsers=)
          ActionDispatch::Request.parameter_parsers = (ActionDispatch::Request.parameter_parsers || {}).merge(parameter_parsers)
        else
          app.middleware.swap("ActionDispatch::ParamsParser",
                              "ActionDispatch::ParamsParser", parameter_parsers)
        end
      end
    end
  end
end
```
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