Identify GET and POST parameters in Ruby on Rails

Question

What is the simplest way to identify and separate GET and POST parameters from a controller in Ruby on Rails, which will be equivalent to $_GET and $_POST variables in PHP?

Answer 1

You can use the request.get? and request.post? methods to distinguish between HTTP Gets and Posts.

• See http://api.rubyonrails.org/classes/ActionDispatch/Request.html

Answer 2

I don't know of any convenience methods in Rails for this, but you can access the querystring directly to parse out parameters that are set there. Something like the following:

request.query_string.split(/&/).inject({}) do |hash, setting|
  key, val = setting.split(/=/)
  hash[key.to_sym] = val
  hash
end

Answer 3

You can do it using:

request.POST

and

request.GET

Answer 4

There are three very-lightly-documented hash accessors on the request object for this:

• request.query_parameters - sent as part of the query string, i.e. after a ?
• request.path_parameters - decoded from the URL via routing, i.e. controller, action, id
• request.request_parameters - All params, including above as well as any sent as part of the POST body

You can use Hash#reject to get to the POST-only params as needed.

Source: http://guides.rubyonrails.org/v2.3.8/action_controller_overview.html section 9.1.1

I looked in an old Rails 1.2.6 app and these accessors existed back then as well.

Answer 5

There is a difference between GET and POST params. A POST HTTP request can still have GET params.

GET parameters are URL query parameters.

POST parameters are parameters in the body of the HTTP request.

you can access these separately from the request.GET and request.POST hashes.

Answer 6

request.get? will return boolean true if it is GET method,

request.post? will return boolean true if it is POST method,

Answer 7

If you want to check the type of request in order to prevent doing anything when the wrong method is used, be aware that you can also specify it in your routes.rb file:

map.connect '/posts/:post_id', :controller => 'posts', :action => 'update', :conditions => {:method => :post} 

or

map.resources :posts, :conditions => {:method => :post} 

Your PostsController's update method will now only be called when you effectively had a post. Check out the doc for resources.

Answer 8

I think what you want to do isn't very "Rails", if you know what I mean. Your GET requests should be idempotent - you should be able to issue the same GET request many times and get the same result each time.

Answer 9

You don't need to know that level of detail in the controller. Your routes and forms will cause appropriate items to be added to the params hash. Then in the controller you just access say params[:foo] to get the foo parameter and do whatever you need to with it.

The mapping between GET and POST (and PUT and DELETE) and controller actions is set up in config/routes.rb in most modern Rails code.

Answer 10

I think what Jesse Reiss is talking about is a situation where in your routes.rb file you have

post 'ctrllr/:a/:b' => 'ctrllr#an_action'

and you POST to "/ctrllr/foo/bar?a=not_foo" POST values {'a' => 'still_not_foo'}, you will have three different values of 'a': 'foo', 'not_foo', and 'still_not_foo'

'params' in the controller will have 'a' set to 'foo'. To find 'a' set to 'not_foo' and 'still_not_foo', you need to examine request.GET and request.POST

I wrote a gem which distinguishes between these different key=>value pairs at https://github.com/pdxrod/routesfordummies.

Answer 11

if request.query_parameters().to_a.empty?