Getting the rails 'params' without the defaults?

问题:

Is there a neat way in rails to get a hash of the params without the default ones of 'action' and 'controller'? Essentially without any param that wasn't added by me.

I've settled for:

parm = params.clone parm.delete('action') parm.delete('controller'); 

But wondering if there is a neater way to do this?

回答1:

You could use except:

params.except(:action, :controller) 

http://as.rubyonrails.org/classes/ActiveSupport/CoreExtensions/Hash/Except.html

回答2:

If you are working in a controller, you should also have access to the request object.

To make a long story short, rails and rack groom incoming GET/POST requests (form, xml, json) and pull out the parameters so that developers have a consistent way of accessing them.

ActionDispatch exposes the consolidated list of params via:

# ActionPack 3.1.8 - action_dispatch/http/parameters.rb # Returns both GET and POST \parameters in a single hash. def parameters   @env["action_dispatch.request.parameters"] ||= begin     params = request_parameters.merge(query_parameters)     params.merge!(path_parameters)     encode_params(params).with_indifferent_access   end end alias :params :parameters 

As you can see, params is an alias for the parameters method which is a merged hash of two sub-hashes: request_parameters and path_parameters.

In your case, you don't want the path_parameters. Rather than using except, which forces you to know which path parameters you want to exclude, you can access your data via: request.request_parameters.

A word of caution: You may be better off using :except if you require the hash to be encoded and keys to be accessed as either strings or symbols. The last line of the parameters method handles that for you:

encode_params(params).with_indifferent_access 

An alternative approach using except and ensuring that you are removing all rails non-request parameters:

path_params = request.path_parameters params.except(*path_params.keys) 

回答3:

request.path_parameters 

returns path_parameters

request.query_parameters 

returns request_parameters

You are looking for the latter.

回答4:

use

request.request_parameters 

it excludes the path_parameters (controller and action)

回答5:

I use

request.request_parameters.except(controller_name.singularize) 

This strips out the nested object that is named after the active controller. For example with the following controller:

Class SessionController > ActionController::Base   def create           User.find_by(params[:email]).login(password: params[:password])    puts request.request_parameters   end end 

With the following posted value from a web form:

{email: 'test@example.com', password: 'password123'} 

The console output will be:

{"email"=>"test@example.com", "password"=>"password123", "session"=>{"email"=>"test@example.com", "password"=>"password123"}} 

The above lines of code avoid this.

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