Determine the domain in an ActiveRecord model - ruby-on-rails

I am in the middle of migrating my application from using subdirectories for userspace to subdomains (ie. domain.com/~user to user.domain.com). I've got a method in my user class currently to get the "home" URL for each user:
class User
def home_url
"~#{self.username}"
# How I'd like to do it for subdomains:
#"http://#{self.username}.#{SubdomainFu.host_without_subdomain(request.host)}"
end
end
I'd like to update this for subdomains, but without hardcoding the domain into the method. As you can see, I am using the subdomain-fu plugin, which provides some methods that I could use to do this, except that they need access to request, which is not available to the model.
I know it's considered bad form to make request available in a model, so I'd like to avoid doing that, but I'm not sure if there's a good way to do this. I could pass the domain along every time the model is initialized, I guess, but I don't think this is a good solution, because I'd have to remember to do so every time a class is initialized, which happens often.

The model shouldn't know about the request, you're right. I would do something like this:
# app/models/user.rb
class User
def home_url(domain)
"http://#{username}.#{domain}"
end
end
# app/controllers/application_controller.rb
class ApplicationController < ActionController::Base
# ...
def domain
SubdomainFu.host_without_subdomain(request.host)
end
# Make domain available to all views too
helper_method :domain
end
# where you need it (controller or view)
user.home_url(domain)
If there is such a thing as a canonical user home URL, I would make a configurable default domain (e.g. YourApp.domain) that you can use if you call User#home_url without arguments. This allows you to construct a home URL in places where, conceptually, the "current domain" does not exist.

While molf's answer is good, it did not solve my specific problem as there were some instances where other models needed to call User#home_url, and so there would be a lot of methods I'd have to update in order to pass along the domain.
Instead, I took inspiration from his last paragraph and added a base_domain variable to my app's config class, which is the set in a before_filter in ApplicationController:
module App
class << self
attr_accessor :base_domain
end
end
class ApplicationController < ActionController::Base
before_filter :set_base_domain
def set_base_domain
App.base_domain = SubdomainFu.host_without_subdomain(request.host)
end
end
And thus, when I need to get the domain in a model, I can just use App.base_domain.

Related

Rails: How to POST internally to another controller action?

This is going to sound strange, but hear me out...I need to be able to make the equivalent of a POST request to one of my other controllers. The SimpleController is basically a simplified version of a more verbose controller. How can I do this appropriately?
class VerboseController < ApplicationController
def create
# lots of required params
end
end
class SimpleController < ApplicationController
def create
# prepare the params required for VerboseController.create
# now call the VerboseController.create with the new params
end
end
Maybe I am over-thinking this, but I don't know how to do this.
Inter-controller communication in a Rails app (or any web app following the same model-adapter-view pattern for that matter) is something you should actively avoid. When you are tempted to do so consider it a sign that you are fighting the patterns and framework your app is built on and that you are relying on logic has been implemented at the wrong layer of your application.
As #ismaelga suggested in a comment; both controllers should invoke some common component to handle this shared behavior and keep your controllers "skinny". In Rails that's often a method on a model object, especially for the sort of creation behavior you seem to be worried about in this case.
You shouldn't be doing this. Are you creating a model? Then having two class methods on the model would be much better. It also separates the code much better. Then you can use the methods not only in controllers but also background jobs (etc.) in the future.
For example if you're creating a Person:
class VerboseController < ApplicationController
def create
Person.verbose_create(params)
end
end
class SimpleController < ApplicationController
def create
Person.simple_create(params)
end
end
Then in the Person-model you could go like this:
class Person
def self.verbose_create(options)
# ... do the creating stuff here
end
def self.simple_create(options)
# Prepare the options as you were trying to do in the controller...
prepared_options = options.merge(some: "option")
# ... and pass them to the verbose_create method
verbose_create(prepared_options)
end
end
I hope this can help a little. :-)

Rails convention for method in multiple controllers

I have an app that has users whose profiles are accessible via site.com/username. When choosing a username, I make an AJAX call to a method in my UsersController to make sure the username is available (and check on the back end as well when submitted). I now want to add groups that will also be accessible through site.com/groupname. Since group and user names cannot collide, whatever controller method that responds to the AJAX call will need to check both so the check_username_available and check_groupname_available methods will do the exact same thing. What's the best practice / Rails way to handle this since I don't want to replicate code in both UsersController and GroupsController?
Having a method for each controller seems a bit redundant, even if the functionality is pulled out to a helper, since there will still be two routes that do the same thing. Having a separate controller solves the problem too but not sure this is good Rails practice.
code that is reused can be shared via a module
class UsersController < ActionController::Base
include NameUniqueness
end
class GroupsController < ActionController::Base
include NameUniqueness
end
module NameUniqueness
protected
def check_name
# implementation here
end
end
both controllers will now have access the check_name instance method.
DanPickett's answer is great.
Another choice is to make a class method in the user model and just call it from each controller. Since this name checking seems like a job for the model, that's what I would do.
class User
def self.check(stuff) ...

How to get the current instance module in Ruby

That title doesn't really explain everything so here goes. I have two Rails engines that share some functionality (ie. user model and authentication). I have a base User class and then two other User classes that inherit from this base class for each app like so:
class User; end
class App1::User < ::User; end
class App2::User < ::User; end
My authentication has a method similar to the following
def user_from_session
User.find_by_id(session[:user_id])
end
which is included in my application_controller. My problem here is that when a user is fetched... it always uses the base User class. What I really want is to be able to fetch a User that is the same type as the app calling that method.
For instance, if a user is on SomeController:
class App1::SomeController < ApplicationController; end
I want the method in the application_controller to pull out the App1 so that it instantiates an App1::User rather than just a User
Is this possible?
I'm NOT looking for a solution that involves two user_from_session methods, one for each application. I am aware of how to implement that. I'm more interested in know if this type of thing is possible in Ruby.
Though I'd caution you to find a better, less hacky way to do this, here's how you might do it:
def user_from_session
# App1::Whatever::FooController -> App1::Whatever
module_name = self.class.name.split('::')[0..-2].join('::')
# App1::Whatever -> App1::Whatever::User
user_class = "#{module_name}::User".constantize
# App1::Whatever::User.find_by_id(...)
user_class.find_by_id(session[:user_id])
end

Ruby on Rails - Access controller variable from model

I am trying to access an instance variable which is set in the controller in the model. The controller is the products controller and the model is the products model. The instance variable is a instance of another model called account.
The instance variable is #current_account
When I run the code nothing happens, I do not get an error. Does anyone know where I can find something read about access instance variables set in the controller from the model?
Thanks
Eef
You shouldn't generally try to access the controller from the model for high-minded issues I won't go into.
I solved a similar problem like so:
class Account < ActiveRecord::Base
cattr_accessor :current
end
class ApplicationController < ActionController::Base
before_filter :set_current_account
def set_current_account
# set #current_account from session data here
Account.current = #current_account
end
end
Then just access the current account with Account.current
DISCLAIMER: The following code breaks MVC conventions, that said...
Using class attributes can probably lead to thread safety issues. I would use Thread.current + around_filter to store controller related data at thread level, and ensure it gets cleared
just before the request finishes:
class ApplicationController < ActionController::Base
around_filter :wrap_with_hack
def wrap_with_hack
# We could do this (greener solution):
# http://coderrr.wordpress.com/2008/04/10/lets-stop-polluting-the-threadcurrent-hash/
# ... but for simplicity sake:
Thread.current[:controller] = self
begin
yield
ensure
# Prevent cross request access if thread is reused later
Thread.current[:controller] = nil
end
end
end
Now the current controller instance will be avaliable globaly during the request processing through Thread.current[:controller]
If you need to access a controller variable from a model it generally means your design is wrong because a controller serves as bridge between view and model (at least in Rails), controller gets info from models, models shouldn't know anything about controllers, but if you want to do it anyway you can do it just as jeem said, but I'd rather do:
class << self
attr_accessor :current
end
instead of cattr_accessor :current
you can see why here => cattr_accessor doesn't work as it should
I can't comment directly so I'll post here: the accepted answer does not seem to be right. As #vise notes, class variables are shared across requests. So unless there's just one current account for the entire app, this won't behave as expected.
For more, see the accepted answer by #molf here: Is Rails shared-nothing or can separate requests access the same runtime variables?
I'm not sure if I understand the question exactly, but I'll take a stab.
I think if you need to access a controller instance variable from the model then you either need to make it an attribute in the model, or move your logic to the other class controller, not model.

Rails: macro style functions

In models and controllers, we often use Rails macros like before_validation, skip_before_filter on top of the class definition.
How is this implemented? How do I add custom ones?
Thanks!
They're just standard Ruby functions. Ruby's flexible approach to syntax makes it look better than it is. You can create your own simply by writing your method as a normal Ruby function and doing one of the following:
putting it somewhere that's accessible by your controllers such as application.rb
putting it in a file and requiring it in.
mixing the code into a class via the Ruby include keyword.
That last option is great for model classes and the first option is really only for controllers.
An Example
An example of the first approach is shown below. In this example we add code into the ApplicationController class (in application.rb) and use it in the other controllers.
class BusinessEntitiesController < ApplicationController
nested_within :Glossary
private
# Standard controller code here ....
The nested_within provides helper functions and variables to help identify the id of the "parent" resource. In effect it parses the URL on the fly and is accessible by every one of our controllers. For example when a request comes into the controller, it is automatically parsed and the class attribute #parent_resource is set to the result of a Rails find. A side effect is that a "Not Found" response is sent back if the parent resource doesn't exist. That saves us from typing boiler plate code in every nested resource.
That all sounds pretty clever but it is just a standard Ruby function at heart ...
def self.nested_within(resource)
#
# Add a filter to the about-to-be-created method find_parent_id
#
before_filter :find_parent_id
#
# Work out what the names of things
#
resource_name = "#{resource.to_s.tableize.singularize}"
resource_id = "#{resource_name}_id"
resource_path = "#{resource.to_s.tableize}_path"
#
# Get a reference to the find method in the model layer
#
finder = instance_eval("#{resource}.method :find_#{resource_name}")
#
# Create a new method which gets executed by the before_filter above
#
define_method(:find_parent_id) do
#parent_resource = finder.call(params[resource_id])
head :status => :not_found, :location => resource_path
unless #parent_resource
end
end
The nested_within function is defined in ApplicationController (controllers/application.rb) and therefore gets pulled in automatically.
Note that nested_within gets executed inside the body of the controller class. This adds the method find_parent_id to the controller.
Summary
A combination of Ruby's flexible syntax and Rail's convention-over-configuration makes this all look more powerful (or weirder) than it actually is.
Next time you find a cool method, just stick a breakpoint in front of it and trace through it. Ahh Open Source!
Let me know if I can help further or if you want some pointers on how that nested_within code works.
Chris
Chris's answer is right. But here's where you want to throw your code to write your own:
The easiest way to add Controller methods like that is to define it in ApplicationController:
class ApplicationController < ActionController::Base
...
def self.acts_as_awesome
do_awesome_things
end
end
Then you can access it from individual controllers like so:
class AwesomeController < ApplicationController
acts_as_awesome
end
For models, you want to reopen ActiveRecord::Base:
module ActiveRecord
class Base
def self.acts_as_super_awesome
do_more_awesome_stuff
end
end
end
I personally would put that in a file in config/initializers so that it gets loaded once, and so that I know where to look for it always.
Then you can access it in models like so:
class MySuperAwesomeModel < ActiveRecord::Base
acts_as_super_awesome
end

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