HTTP Controllers

HTTP Controllers can be used as HTTP endpoints. Volt does most client side communication via websockets (or other socket fallbacks) so it does not use HTTP for data synchronization to the client, except for the initial page load. HTTP Controllers provide an easy way to provide data to third parties who need to access data (a REST API for example) via HTTP.

Routing

To use HTTP Controller you need to set up corresponding routes in your Routes File.

Creating a controller

You can create an HTTP Controller by placing a file under app/component_name/controllers/server/ and inherit from Volt::HttpController

module Main
  class TodosController < Volt::HttpController
    def index
      #perform some action
    end
  end
end

By convention the class name has to end with "Controller". In volt, the server folder denotes that the code should only be loaded on the server. Keep in mind however that your controller name should not be the same as another controller (ModelController or HttpController) in the component.

Params

You have access to the params via the #params method. Unlike the params available in the Controllers, #params inside a Volt::HttpController is a simple hash with symbolized keys. They keys :controller, :action and are set to the controller and performed action. You can overwrite the HTTP method by setting the :method to either

Accessing the store

Within your controller you can access your store via the provided #store method.

Accessing the request body

For now the request body has to be parsed manually. You can access the body via the request object.

module Main
  class TodosController < Volt::HttpController
    def create
      data = JSON.parse(request.body.read)
      store._links! << Link.new(data)
    end
  end
end

Responding to a request

You can respond to a request via the #render, #head or #redirect_to methods.

Rendering a response

You can respond to a request by rendering JSON or plain text using the #render method. #render takes a hash as argument. You need to either set the :json or :text key.

module Main
  class TodosController < Volt::HttpController
    def show
        data = { some: "data" }
        render json: data
    end
  end
end

By default rendering will respond with HTTP status code 200. You can overwrite this by adding the status: key to the argument hash. All remaining keys are processed as additional HTTP headers.

Redirecting

Redirecting can be done with the #redirect_to method. You have to supply a location as first argument and a status code as optional second argument. the default status code is 302.

module Main
  class TodosController < Volt::HttpController
    def create
        #do something
        redirect_to '/todos'
    end
  end
end

head

If neither redirecting nor rendering a response is required, you can just set the status with the #head method.

#head takes a status code as first argument and an optional hash with additional headers as second. You can use the symbols as status code. See the HTTP_STATUS_CODES section in http://www.rubydoc.info/github/rack/rack/Rack/Utils for more details.

module Main
  class TodosController < Volt::HttpController
    def create
        head :no_content
    end
  end
end

Headers

You can add custom HTTP headers to your response. The custom headers will be transformed:

:auth_token will be transformed to 'Auth-Token'. You can either set headers by using a Symbol or a String. :auth_token == 'Auth-Token' == 'auth-token' == 'Auth_Token'