I'm using the Rails gem SimpleForm, but I think my question may be applicable to any gem.
https://github.com/plataformatec/simple_form
It has a lot of great features and customization, but I'm looking to go a bit further. For example, I really wish the markup generated had no default classes inserted into it, but I'd still like the ability to insert my own manually. I found that I could remove some of the classes by commenting out lines in the gem files. However this is outside of my project-- I would want a DRY solution that will stay with my project when I deploy to production, preferably without having to pack all of my gems.
I imagine this is a common situation that could apply to any gem, and I should be able to override any gem wholly or partially probably by adding customs files in my project that override the gem... but I'm not sure how.
Any help would be appreciated! Thanks.
Are you talking about monkey patching? Say your gem has a class in a file
# simple_form_gem/lib/some_file.rb
class A
def some_method
puts 'A'
end
end
If you want to change the output of #some_method then you can create an initializer file and do
# config/initializers/my_monkey_patch_for_simple_form_gem.rb
class A
def some_method
puts 'duck punching'
end
end
Your monkey patch will only affect A#some_method, and not other methods in A. Just make sure the output of your monkey patch won't break something else in the gem.
Related
The README for the annotate gem mentions models, fixtures, specs, and files generated by specific gems, but not presenters.
Is there any way to make annotate add annotations to presenters?
There doesn't seem to be a gem-supported way to add model annotations to other types of classes which wrap around models, like presenters, decorators, and exhibitors. But, since pretty much all the main code in the gem is in a single file (lib/annotate/annotate_models.rb), you could bundle open annotate and hack around on it to get what you want, assuming you don't mind a bit of monkey patching. For example, assuming your presenters are in app/presenters, you could make the following kinds of edits to the file directly:
module AnnotateModels
# Towards the top of the file where all the directory
# declarations are...
PRESENTER_DIR = File.join("app", "presenters")
PRESENTER_TEST_DIR = File.join("test", "presenters")
PRESENTER_SPEC_DIR = File.join("spec", "presenters")
PRESENTER_PATTERNS = [
File.join(PRESENTER_DIR, "%MODEL_NAME%_presenter.rb"),
File.join(PRESENTER_TEST_DIR, "%MODEL_NAME%_presenter_test.rb"),
File.join(PRESENTER_SPEC_DIR, "%MODEL_NAME%_presenter_spec.rb"),
]
# ...
def annotate
# ...
# add in presenters to the list of file types that require annotations
%w(test fixture factory serializer presenter).each do |key|
# ...
end
end
def remove_annotations
# ...
# add presenter files to list needing annotation removal
(TEST_PATTERNS + FIXTURE_PATTERNS + FACTORY_PATTERNS + SERIALIZER_PATTERNS + PRESENTER_PATTERNS).map { ... }
end
# ...
end
Certainly not an elegant solution, but if this kind of change works for you, you could consider forking the gem and moving any changes there, or maybe even submit a pull request back to the gem. Looking at the annotate gem issue tracker, there doesn't seem to have been any feature requests or discussion around the addition of presenters or decorators to the file types that could be annotated.
I have a Rails app that uses a gem called ActsAsTaggableOnSteroids, which is a Rails Engine. Specifically, I'm using PavelNartov's fork of the gem. But nevermind that.
I need to add specific functionality to the Tag model, which is supplied by the engine.
But, according to my understanding of Rails engines and the magical loading functionality in Rails, if I put a file called "tag.rb" in my models directory, then it will completely replace the one from the Engine.
Ideally, I would be able to do something like:
class Tag < ActsAsTaggable::Tag
# my stuff
end
...but alas, that doesn't work because the model supplied by the engine is not namespaced.
So, I came up with this nightmare, which I put in app/models/tag.rb:
path = ActsAsTaggable::Engine.config.eager_load_paths.grep(/models/).first
require File.join(path, 'tag')
Tag.class_eval { include TagConcern }
But there has to be a better way! I feel like I'm missing something. I'd prefer not to add this strangeness to my app if possible.
Just require the file by looking up the path of the gem's model:
require File.join(Gem::Specification.find_by_name("bborn-acts_as_taggable_on_steroids").gem_dir, 'app/models/tag')
Tag.class_eval do
# ...
end
This is more a theoretical question, but I am curious anyway. I am a ruby / ruby on rails newbie (but with a lot of ancient experience in other languages / frameworks) so this is mainly a curious / learning question. Thanks in advance for any help!
I thought I could do a quick extension to a ruby gem using alias as follows:
module InstallMyExtension
def self.included(base)
base.class_eval {
alias :some_method_in_gem_without_my_extension :some_method_in_gem
alias :some_method_in_gem :some_method_in_gem_with_my_extension
}
end
def some_method_in_gem_with_my_extension
debugger
# ... do fun stuff here
some_method_in_gem_without_my_extension
end
end
Then in some initialization file I do:
Foo::SomeControllerInFoo.send :include, InstallMyExtension
I learned this technique in the Radiant CMS where its used all over the place to extend base behavior. I understand this technique is now disapproved of, but it seemed like a quick way to just try some ideas out, before forking a branch on the gem, etc, etc
First off is there a better way in Rails 3 to do a quick hack extension like this (which might be useful just to test a theory, before forking the gems etc???)
Second off, its not working, and there are multiple things I don't understand
Then let me explain the weirdness I am seeing:
Even if I do do the the "include" as shown above, when I go into the console I see some really weird behavior, that I don't understand:
1) I type Foo::SomeControllerInFoo i get back Foo::SomeControllerInFoo as I would expect. HOWEVER if run the same exact expression a second time, Foo::SomeControllerInFoo comes back undefined!
2) Just to play around I did foo = Foo::SomeControllerInFoo, and then I can do foo.send, foo.methods, whatever I like, but only if I save the copy of the class in foo! What's with that?
3) If I now do foo.send :include, MyExtension the behavior within the debug console is as expected (i.e. the original class contained in the gem now has my behavior added to it.) HOWEVER running the same code during initialization has no effect. Nothing breaks, but the controller is not extended.
Weird that it doesn't work, I just tried again to be sure and that does the trick (put this code in a file within config/initializers).
I always use a shortcut:
alias_method_chain :some_method_in_gem, :my_extension
instead of the two aliases lines, but it's exactly the same.
You could overwrite some methods much more easily using class_eval directly. Again in an initializer:
Foo::SomeControllerInFoo.class_eval do
def some_method_in_gem
#your redefinition
end
end
Sorry but no added value for your other questions: seems just really weird and buggy.
Just to be sure, when you want to run the method defined in your controller, do:
c = Foo::SomeControllerInFoo.new
c.method_name
I successfully created a gem having some classes and modules to be'ing able to to something like that in ANY kind of class in a Rails project:
class AnyRubyOrActiveModelClass
acts_as_anything [:foo, :bar]
def foo
.. do some foo
end
def self.bar
.. do some bar
end
end
To do so I created a Module in my gem that looked something like that:
module InstanceMagic
class << self.class.superclass
define_method(:acts_as_anything) do |methods|
self.class_eval do
include ClassMagic
.. do some alias_method with given methods
end
end
end
This module successfully aliased my method :foo from the example above, the second module ClassMagic did the same for my :bar class method (following the advice from here).
In a testproject that approach worked very well. In a real life project it led to interference with another gem taking a - maybe similar - approach. This gem complained about missing methods in a class even when I only integrated my gem into the project - not even integrated acts_as_anything into the class.
So I broke down my code to only that:
module InstanceMagic
class << self.class.superclass
define_method(:acts_as_anything) do |methods|
#really empty here
end
end
As a result the other gem still breaks.
I used class << self.class.superclass to explicitly extend Object, so that even non ActiveSomething classes but ALL classes are affected and my acts_as_anything is available. So I remain with three questions.
Why do the last 5 lines of code break another gem and making it complain about missing methods it's trying to dynamically create? I would like to understand.
Is there a better approach to achieve my goal?
When I use method_added and singleton_method_added (what I actually do inside my modules), should I look for these methods whether they already exist, alias the "original" ones, insert my ones and call the original ones after I have done my job?
Knowing this is a lot I still hope someone can point me into the right direction.
Thank you.
Felix
The only thing I can think of is some sort of order dependency (long shot). Try to put your code in an initializer in the rails app and see if it still causes the same problems.
What is the recommended way to extend class behavior, via class_eval and modules (not by inheritance) if I want to extend a class buried in a Gem from a Rails 3 app?
An example is this:
I want to add the ability to create permalinks for tags and categories (through the ActsAsTaggableOn and ActsAsCategory gems).
They have defined Tag and Category models.
I want to basically do this:
Category.class_eval do
has_friendly_id :title
end
Tag.class_eval do
has_friendly_id :title
end
Even if there are other ways of adding this functionality that might be specific to the gem, what is the recommended way to add behavior to classes in a Rails 3 application like this?
I have a few other gems I've created that I want to do this to, such as a Configuration model and an Asset model. I would like to be able to add create an app/models/configuration.rb model class to my app, and it would act as if I just did class_eval.
Anyways, how is this supposed to work? I can't find anything that covers this from any of the current Rails 3 blogs/docs/gists.
I do this as follows, first add a file to config/initializers where you can require the files that contain your extensions:
# config/initializers/extensions.rb
require "#{Rails.root}/app/models/category.rb"
require "#{Rails.root}/app/models/tag.rb"
Then you can just re-open the classes and add whatever else you need:
# app/models/category.rb
class Category
has_friendly_id :title
end
Only downside is that the server has to be restarted for any changes to these files to take effect, not sure if there is a better way that would overcome that.
You can use rails_engine_decorator gem:
https://github.com/atd/rails_engine_decorators
Just add in your Gemfile:
gem 'rails_engine_decorator'
And user class_eval in your decorators:
/app/decorators/models/category_decorator.rb
/app/decorators/models/tag_decorator.rb
It works for me. I hope you find it useful!