I have the following scenario
I want to add methods dynamically to a controller. All my method names are in a table . Please refer the following example
-table (method_names)-
1 - Walk
2 - Speek
3 - Run
and I have a controller
class UsersController < ApplicationController
def index
end
end
Inside this index action i want to call my methods dynamically. Those methods were actually implemented else ware.
I have another controller like
class ActionImplementController < ApplicationController
def walk
puts "I'm walking"
end
def speek
puts "I'm sppeking"
end
def run
puts "I'm running"
end
end
** I have done something like below and its working
class UsersController < ApplicationController
def index
a = eval("ActionImplementController.new.run")
end
end
But my question is , is this the right way or is there anyother way to do this
Thanks in advance
cheers
sameera
While the first answer works, i would prefer something like this
module ImplementsActions
def run
...
end
def walk
..
end
def ...
end
and then in your controller write
class UsersController < ActionController::Base
include ImplementsActions
# now you can just use run/speek/walk
def index
run
end
end
Much cleaner because the code can be shared, but it is defined where you need it.
I think it's generally best to avoid the use of eval. If you can, I would make all your methods class methods and then run them like so:
def index
ActionImplementController.send :run
# ActionImplementController.new.send(:run) works if you can't use class methods
end
Related
I'm relatively new to Rails and am working on creating a simple user authentication system to get to grips with how Rails works.
I'm currently at the point where I'd like to create some methods that I can use in my controllers like so:
is_logged? # => true
and
current_user_id # => 6
These would be used to interact with sessions, mainly so I'm not repeating myself in the controller.
Where would I define these functions and how would I include them in a controller?
Thanks a lot in advance for any help.
Method 1
You can define these method in helper files, inside app/helpers/my_module.rb. You can create a module there, put all the methods inside of it, and then include the modules in your control to use these method.
module MyMoule
def is_logged?
...
end
end
Then in you class include the module
class MyClassController < ApplicationController
include MyModule
def my_method
#Use it like this
logged_in = MyModule.is_logged?
end
end
Method 2
If you using session related stuff you can always put them inside application_controller.rb. And since all your controller will inherit ApplicationController the methods will be available to you.
class ApplicationController < ActionController::Base
def is_logged?
...
end
end
In your other controller you can use them directly.
class MyClassController < ApplicationController
def my_method
logged_in = is_logged?
end
end
class UsersController < ApplicationController
def create
# call the action do_something from ImagesController
# continue in the normal flow
end
end
class ImagesController < ApplicationController
def do_something
...
end
end
I want to call the action do_something in the ImagesController from UsersController but after it is executed I want to continue in the normal flow of the create action, few questions:
Is it a bad practice?
How can I do that? Do I have to create an instance of the ImagesController and then call the action or is there another way?
You could technically create an instance of the other controller and call methods on that, but it is tedious, error prone and highly not recommended.
If that function is common to both controllers, you should probably have it in ApplicationController or another superclass controller of your creation.
class ApplicationController < ActionController::Base
def common_to_all_controllers
# some code
end
end
class SuperController < ApplicationController
def common_to_some_controllers
# some other code
end
end
class MyController < SuperController
# has access to common_to_all_controllers and common_to_some_controllers
end
class MyOtherController < ApplicationController
# has access to common_to_all_controllers only
end
another method is
# lib/common_stuff.rb
module CommonStuff
def common_thing
# code
end
end
# app/controllers/my_controller.rb
require 'common_stuff'
class MyController < ApplicationController
include CommonStuff
# has access to common_thing
end
source - Calling a method from another controller
this is possible actually. And not that hard.
That said. It is bad practice. Very bad practice.
What you want to do is extract the logic you do in the controller you want to invoke into a service object or move it into a model. Alternativly you could also make your first controller inherit from the one you are trying to invoke.
So, how to call a controller?
TheController.new.dispatch(:index, request)
Suppose I have some logic in a base controller to pass information to the view to build something like a breadcrumb:
class ContextAwareController < ApplicationController
after_filter :build_breadcrumb
def build_breadcumb
#...
end
end
I want this build_breadcrumb method to run after the main controller logic, but before the view is rendered.
The above code runs too late, but a before_filter would be too early.
Can anybody suggest a way to accomplish this without explicitly calling build_breadcumb at the end of each of the actions in the child controllers?
Thanks
I had the same problem and solved it like this:
class ApplicationController < ActionController::Base
def render *args
add_breadcrumbs
super
end
end
There are also some gems to achieve this. One of them is rails3_before_render.
It works similarly to filters, for example:
class PostsController < ApplicationController
before_render :ping, :except => [:destroy]
def index; end
def new; end
def show; end
def destroy; end
private
def ping
Rails.logger.info "Ping-Pong actions"
end
end
(code snipped copied from gem documentation)
I believe rendering starts when render is called, and there's no default way to defer it. Here's one thing you could do:
filters are applied in the same order declared. So make a second after-filter that calls render with an array args stored in a class variable. Then anywhere you would normally call render, set the variable.
If we're overriding render, we're not really using the filter chain at all, so it might be simpler to determine which action we're in using the #_action_name.
StuffController < ApplicationController
def my_filter
# Do the stuff
end
def render(*args)
my_filter if #_action_name == "show"
super
end
end
You can use alias_method_chain like this
alias_method_chain :render, :before_render_action
this will create 2 methods :render_with_before_render_action and :render_without_before_render_action. If you call render, then :render_with_before_render_action will be called. You can override this method
def render_with_before_render_action(*options, &block)
<your code>
render_without_before_render_action(*options, &block)
end
If you don't want your code to be executed and you want to have default render then you should directly call the :render_without_before_render_action
You can do like this to fake a before_render:
class StuffController < ApplicationController
before_filter :my_filter, only: [:index, :show]
def my_filter
#my_filter = true
end
def _my_filter
# Do the actual stuff here
end
def render(*args)
_my_filter if #my_filter
super
end
end
Thanks to #joshua-muheim for the tip about using render
I have a controller called ProjectsController. Its actions, by default, look for views inside app/views/projects. I'd like to change that path for all methods (index, show, new, edit etc...) in the controller.
For example:
class ProjectsController < ApplicationController
#I'd like to be able to do something like this
views_path 'views/mycustomfolder'
def index
#some code
end
def show
#some code
end
def new
#some code
end
def edit
#some code
end
end
Please note I am not changing each method with render but defining a default path for all of them. Is this possible? If so, how?
Thank you!
See ActionView::ViewPaths::ClassMethods#prepend_view_path.
class ProjectsController < ApplicationController
prepend_view_path 'app/views/mycustomfolder'
...
You can do this inside your controller:
def self.controller_path
"mycustomfolder"
end
If there's no built-in method for this, perhaps you can override render for that controller?
class MyController < ApplicationController
# actions ..
private
def render(*args)
options = args.extract_options!
options[:template] = "/mycustomfolder/#{params[:action]}"
super(*(args << options))
end
end
Not sure how well this works out in practice, or if it works at all.
You can add something like:
paths.app.views << "app/views/myspecialdir"
in the config/application.rb file to have rails look in another directory for view templates. The one caveat is that it'll still look for view files that match the controller. So if you have a controller named HomeController with the above config for the views it'll look for something named "app/views/myspecialdir/home/index.html.erb" to render.
If you want to change the default path for all your views at app level, you could do something like following -
class ApplicationController < ActionController::Base
before_action :set_views
private
def set_views
prepend_view_path "#{Rails.root.join('app', 'views', 'new_views')}"
end
end
And write all your views in the folder new_views following the same directory structure as original.
P.S. - This answer is inspired from #mmell's answer.
The accepted answer no longer works for me. After much wailing and gnashing of teeth, I've managed to find that if render is not called in the action, then the default_render method is called. In my case, I needed to override the default_render message in my controller as follows:
def default_render
render "path/to/views/#{action_name.to_s}"
end
To the rails experts out there I was wondering where/how you would execute the same code for every action in your web application? If you can point me to an article or provide a short code snippet I would greatly appreciate it.
Thanks in advance to anyone who can help.
Use a filter in your ApplicationController to run the code for every action in your application. All your controllers descend from ApplicationController, so putting the filter there will ensure the filter gets run.
class ApplicationController
before_filter :verify_security_token
def verify_security_token; puts "Run"; end;
end
It sounds to me like you're talking about filters.
class MyController < ActionController::Base
before_filter :execute_this_for_every_action
def index
#foo = #bar
end
def new
#foo = #bar.to_s
end
def execute_this_for_every_action
#bar = :baz
end
end
You can put the filter on the ApplicationController, too, if you want every controller to run it.
before_filter if you want the code to be executed "before" each action.
If you want the action to be declared each time you use it, you can put it in ApplicationController and call the method in any controller.
Another approach is to use helpers like:
module PersonHelper
def eat
{.. some code ..}
end
end
And in your controller:
class MyController < ActionController::Base
include PersonHelper
def index
eat
end
end