I'm attempting to include an image asset pipeline url in my model serializer output by including ActiveView::Helpers:
class PostSerializer < ActiveModel::Serializer
include ActiveView::Helpers
attributes :post_image
def post_image
image_path "posts/#{object.id}"
end
end
The result is /images/posts/{id} rather than a valid path to the asset pipeline path, ie. /assets/images/posts/{id}. How can I include valid asset pipeline paths in my serializer output?
Maybe this could work:
def post_image
_helpers = ActionController::Base.helpers
_helpers.image_url "posts/#{object.id}"
end
(Very) late to the party, but you can solve the problem by adding this to your ApplicationController :
serialization_scope :view_context
and then in the serializer :
def post_image
scope.image_url('my-image.png')
end
Explanation : When your controller instanciates a serializer, it passes a scope (context) object along (by default, the controller itself I think). Passing the view_context allows you to use any helper that you would be able to use in a view.
So I have been struggling with this for a little bit today. I found a slightly less then ideal solution. The ActionController::Base.helpers solution didn't work for me.
This is certainly not the most optimal solution. My thinking is that the proper solution might be to add a 'set_configs' initializer to ActiveModelSerializer.
The ActionView::Helpers::AssetUrlHelper utilizes a function called compute_asset_host which reads config.asset_host. This property looks to be set in railtie initializers for ActionViews and ActionControllers. ActionController::RailTie
So I ended up subclassing the ActiveModel::Serializer and setting the config.asset_host property in the constructor, like so.
class BaseSerializer < ActiveModel::Serializer
include ActiveSupport::Configurable
include AbstractController::AssetPaths
include ActionView::Helpers::AssetUrlHelper
def initialize(object, options={})
config.asset_host = YourApp::Application.config.action_controller.asset_host
super
end
end
This got me most of the way. These helpers methods also use a protocol value; it can be passed in as a param in an options hash, a config variable, or read from the request variable. so I added a helper method in my BaseSerializer to pass the correct options along.
def image_url(path)
path_to_asset(path, {:type=>:image, :protocol=>:https})
end
Related
Within a Plain Old Ruby Object (PORO) in my rails app: I have the following method:
def some_method
content_tag(:li, link_to("Do something", somewhere_path(object.id)))
end
First: the object didn't understand the method content_tag, so I added the following which made the object understand that method:
include ActionView::Helpers::TagHelper
Then the object didn't understand link_to so I added the following which made the object understand that method:
include ActionView::Helpers::UrlHelper
Now, it doesn't understand my route: somewhere_path(object.id).
Question: How can I make the PORO in my rails app understand the helpers which generate routes?
Followup Question: Is there an easier way to include all of this functionality into my PORO object? Perhaps there is a way to only include one major module and get all of this functionality (as opposed to perhaps needing to require 3 different modules).
You either have to do what you describe in your self-answer (link to revision I refer to), or inject some context into your POROs. Where context is something which knows all those methods. Something like this:
class ProjectsController
def update
project = Project.find(params[:id])
presenter = Presenters::Project.new(project, context: view_context) # your PORO
# do something with presenter
end
end
And your PORO would look like this:
module Presenters
class Project
attr_reader :presentable, :context
def initialize(presentable, context:)
#presentable = presentable
#context = context
end
def special_link
context.somewhere_path(presentable)
end
end
end
Me, I like neither of them. But sometimes we have to choose a lesser evil.
If anyone happens to know of a current way to get access to all of these methods with one include statement then let me know.
Why, yes. There is a way.
module MyViewCompatibilityPack
include ActionView::Helpers::TagHelper
include ActionView::Helpers::UrlHelper
def url_helpers
Rails.application.routes.url_helpers
end
end
class MyPoro
include MyViewCompatibilityPack
...
end
The issue is that actionview-related methods are not available to POROs.
In order to get all the great stuff from actionview: you need to utilize the view_context keyword. Then: you can simply call upon actionview-related methods from your view_context:
class BuildLink
attr_accessor :blog, :view_context
def initialize(blog, view_context)
#blog = blog
#view_context = view_context
end
def some_method
content_tag(:li, link_to(“Show Blog“, view_context.blog_path(blog)))
end
end
So for example: from your controller you would call upon this PORO like so:
BuildLink.new(#blog, view_context).some_method
For more information, see below references:
Rails doc on view_context
Utilization of view_context via presenter pattern, shown in this article
Railscast which talks through utilizing view_context via presenter pattern
I need some help with my plugin. I want to extend ActiveRecord::Base with a method that initializes another method that can be called in the controller.
It will look like this:
class Article < ActiveRecord::Base
robot_catch :title, :text
...
end
My attempt at extending the ActiveRecord::Base class with robot_catch method looks like following. The function will initialize the specified attributes (in this case :title and :text) in a variable and use class_eval to make the robot? function available for the user to call it in the controller:
module Plugin
module Base
extend ActiveSupport::Concern
module ClassMethods
def robot_catch(*attr)
##robot_params = attr
self.class_eval do
def robot?(params_hash)
# Input is the params hash, and this function
# will check if the some hashed attributes in this hash
# correspond to the attribute values as expected,
# and return true or false.
end
end
end
end
end
end
ActiveRecord::Base.send :include, Plugin::Base
So, in the controller, this could be done:
class ArticlesController < ApplicationController
...
def create
#article = Article.new(params[:article])
if #article.robot? params
# Do not save this in database, but render
# the page as if it would have succeeded
...
end
end
end
My question is whether if I am right that robot_catch is class method. This function is to be called inside a model, as shown above. I wonder if I am extending the ActiveRecord::Base the right way. The robot? function is an instance method without any doubt.
I am using Rails 3.2.22 and I installed this plugin as a gem in another project where I want to use this functionality.
Right now, it only works if I specifically require the gem in the model. However, I want it the functionality to be included as a part of ActiveRecord::Base without requiring it, otherwise I'd have to require it in every model I want to use it, not particularly DRY. Shouldn't the gem be automatically loaded into the project on Rails start-up?
EDIT: Maybe callbacks (http://api.rubyonrails.org/classes/ActiveSupport/Callbacks/ClassMethods.html) would be a solution to this problem, but I do not know how to use it. It seems a bit obscure.
First, I would suggest you make sure that none of the many many built in Rails validators meet your needs.
Then if that's the case, what you actually want is a custom validator.
Building a custom validator is not as simple as it might seem, the basic class you'll build will have this structure:
class SpecialValidator < ActiveModel::EachValidator
def validate_each(record, attribute, value)
# Fill this with your validation logic
# Add to record.errors if validation fails
end
end
Then in your model:
class Article < ActiveRecord::Base
validates :title, :text, special: true
end
I would strongly suggest making sure what you want is not already built, chances are it is. Then use resources like this or ruby guides resources to continue going down the custom validator route.
Answer
I found out the solution myself. Bundler will not autoload dependencies from a gemspec that my project uses, so I had to require all third party gems in an engine.rb file in the lib/ directory of my app in order to load the gems. Now everything is working as it should.
Second: the robot_catch method is a class method.
I know this version is still not officially released but I was checking out rc3 today and I noticed that I can no longer use Rails url helpers inside my serializers. In version 0.8.x, I could do the following:
class BrandSerializer < BaseSerializer
attributes :id, :name, :slug, :state
attributes :_links
def _links
{
self: api_v1_company_brand_path(object.company_id, object.id),
company: api_v1_company_path(object.company_id),
products: api_v1_company_brand_products_path(object.company_id, object.id)
}
end
end
But this is a no go in the new version. What's the best way of resolving this so that I can keep my links in my serializer?
Edit:
For now I'm doing the following but would love to hear if there's a more idiomatic way.
class BaseSerializer < ActiveModel::Serializer
include Rails.application.routes.url_helpers
If you add this to your ApplicationController or even probably to the controller generating the response:
serialization_scope :view_context
You can then use the view_context in the serialiser to access the URL helpers (or any view methods really).
Example: view_context.api_v1_company_brand_path(object.company_id, object.id)
I thought this was probably cleaner than including all those URL helpers etc... into the serialiser class.
including the library which had been excluded (as you had done) would most definitely be the shortest route (outside of revising the gem itself, in terms of idiomacy)
I'm writing a script for my rails application and I'm trying to format the numbers with delimeters so they're easier to read. But I have a problem in calling the number_with_delimeter method from ActionView::Helpers::NumberHelpers
I tried
class MyClass < ActiveRecord::base
extend ActiveView::Helpers::NumberHelper
def self.run
puts "#{number_with_delimeter(1234567)}"
end
end
MyClass.run
but it just doesn't work. I always get undefined method errors. I tried it with include instead of extend and some other variations. None of them worked. I don't know how to proceed.
Is there any way to call this method in a script?
*Note: * I call the script with rails r script/my_script.rb
An elegant solution consists in delegation:
def self.run
puts "#{helper.number_with_delimiter(1234567)}"
end
def self.helper
Helper.instance
end
class Helper
include Singleton
include ActionView::Helpers::NumberHelper
end
Sidenotes:
including modules overloads your class
including the helpers didn't help because you were working at the class level.
formatting should not be model's job, you should extract this kind of logic within presenters.
I have several models that share a concern. Each model passes in a hash, which is meant to handle minor differences in the way they use the concern. I pass the hash in through a class method like so:
add_update_to :group, :user
The full code for the concern is:
module Updateable
extend ActiveSupport::Concern
attr_accessor :streams
module ClassMethods
def add_updates_to(*streams)
#streams = streams
end
end
module InstanceMethods
def update_streams
#streams.collect{|stream| self.public_send(stream)}
end
end
included do
has_one :update, :as => :updatable
after_create :create_update_and_history
end
private
def create_update_and_history
update = self.create_update(:user_id => User.current.id)
self.update_streams.each do |stream|
stream.histories.create(:update_id => update.id)
end
end
end
Most of this code works, but I'm having trouble passing the hash from the class to an instance. At the moment, I'm trying to achieve this effect by creating a virtual attribute, passing the hash to the attribute, and then retrieving it in the instance. Not only does this feel hacky, it doesn't work. I'm assuming it doesn't work because #streams is an instance variable, so the class method add_update_to can't actually set it?
Whatever the case, is there a better way to approach this problem?
You could probably use class variables here, but those are pretty reviled in the Ruby community due to their unpredictable nature. The thing to remember is that classes in Ruby are actually also instances of classes, and can have their own instance variables that are only accessible to themselves, and not accessible to their instances (if that is in any way clear).
In this case, you are defining behavior, and not data, so I think neither instance nor class variables are appropriate. Instead, I think your best bet is to define the instance methods directly within the class method, like this:
module Updateable
extend ActiveSupport::Concern
module ClassMethods
def add_updates_to(*streams)
define_method :update_streams do
streams.collect {|stream| public_send(stream) }
end
end
end
end
BTW, there is no hash involved here, so I'm not sure what you were referring to. *streams collects your arguments into an Array.