UPDATE
I wrongly checked the edgerails guide instead of the currently correct Rails 3 guide (which has no mention of after_initialize). Not sure why the edgerails guide is "incorrect" though - I thought edgerails guide was supposed to be the latest up-to-date guide?
I'm leaving this question as-is just in case someone comes looking for the same "problem".
Macro-style call to after_initialize is the way to go.
Should after_initialize be used as method or macro-style call ?
This works, but gives a deprecation warning:
def after_initialize
logger.info "Called after_initialize"
end
DEPRECATION WARNING: Base#after_initialize has been deprecated,
please use Base.after_initialize :method instead.
This works, and there is no warning:
after_initialize :do_this_after_initialize
def do_this_after_initialize
logger.info "Called after_initialize"
end
But the Active Record Validations and Callbacks Guide in 10.4 after_initialize and after_find says:
...If you try to register
after_initialize or after_find using
macro-style class methods, they will
just be ignored. This behaviour is
due to performance reasons, since
after_initialize and after_find will
both be called for each record found
in the database, significantly slowing
down the queries...
So that means that the macro-style usage is inefficient versus the method-style way?
(I guess the guide is wrong, 'cos code is king :D)
Another Update
A commit here from January 28, 2011, suggests that the correct way is still to use the macro-style call, not a def after_initialize.
The call backs should be used as macro style in your model: http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html
Related
I've just upgraded from Rails 5.0.0 to 5.1.1 and started getting a ton of deprecation warnings like this:
DEPRECATION WARNING: The behavior of changed_attributes inside of
after callbacks will be changing in the next version of Rails. The new
return value will reflect the behavior of calling the method after
save returned (e.g. the opposite of what it returns now). To
maintain the current behavior, use
saved_changes.transform_values(&:first) instead.
and this:
DEPRECATION WARNING: The behavior of attribute_changed? inside of
after callbacks will be changing in the next version of Rails. The new
return value will reflect the behavior of calling the method after
save returned (e.g. the opposite of what it returns now). To
maintain the current behavior, use saved_change_to_attribute?
instead.
I don't use those methods explicitely anywhere in my project and the warnings are pointing mostly at create and update calls on my models.
I believe it has something to do with my validations and after_update and after_create callbacks where I use confitions like if: { author_id_changed? } but I have no idea what to do with them.
I also believe the warning is related to this massive update to ActiveRecord.
Would appreciate any hand you can give with this.
UPD
This article helped alot!
Well, got around everything by running bundle update and updating the gems and also following this article and changing attribute_changed? calls in after_ callbacks (but not in before_ callbacks and validations) and switching from attribute_was to attribute_before_last_save.
For After callbacks, you can use saved_change_to_attribute?
For Before callbacks and validations, you can use will_save_change_to_attribute?
I hope this information will help!
I've done an upgrade to Rails 5.1.6 and have the same DEPRECATION warnings. If ever anyone still wants to solve this warning. Here are the steps I took:
Search all of your*_changed?
Changed this:
if name_changed?
...
if user_id_changed?
To this if it is inside after_* (after_save, after_commit, after_update, etc.) blocks:
if saved_change_to_name?
...
if saved_change_to_user_id?
AND to this if it is inside before_* (before_save, before_commit, before_update, etc.) blocks:
if will_save_change_to_name?
...
if will_save_change_to_user_id?
On my own opinion, this is quite tricky thing to change since we've been used to attribute_changed?. But change is good. The syntax also made more sense now.
You can change author_id_changed? to saved_change_to_author_id?
In Rails 5, when a callback needs to cancel later callbacks, the recommended process is documented as "you should explicitly throw :abort."
My question is: how is it recommended that this exception be caught?
My current solution is to catch UncaughtThrowError in my ApplicationController - given the way it's documented, I thought this feature would trigger some magic in Rails or a Rack middleware to immediately move to the rendering (ActionView) phase.
Here are some examples of how to use the throw/catch in ruby.
For Rails, I think something like this will do the trick:
class SomeController
def some_method
if catch(:abort) { mode.save }
# success
else
# failure
end
end
end
You would probably have to write a method that overrides the underlying method for processing callbacks to have a catch :abort {} that handles it, which feels like too much magic.
I think using a rescue_from UncaughtThrowError in the controller you're throwing in seems a better approach vs. having it in the ApplicationController unless this is really common callback, in which case you probably want a Concern?
I went down this road for a day, and then decided to not use a callback for what I wanted to do, which eliminated the whole need for the callbacks, throws, rescues, and catches.
Still, I'm sure there are good cases for this approach, but it's not well documented as to how.
This is maybe more of a philosophical question, but...
As I'm working with rspec and rails, I'm getting more comfortable with using mock objects and stubs to isolate my controller tests from my models, and vice versa.
However, that leaves me with a lingering feeling that not everything is connected properly.
As an example, I might have a spec for a controller like this:
it "passes a list of awesome cheeses to the view" do
Cheese.should_receive(:awesome).and_return( [ ] ) # one method name
get 'show'
assigns[:awesome_cheeses].should_not be_nil
end
And then a spec on my Cheese model like:
it "should return a list of awesome cheeses" do
Cheese.create!(:name => "American", :is_awesome => false)
Cheese.create!(:name => "Gouda", :is_awesome => true)
Cheese.awesome_cheeses.should_not be_nil # different method name!
end
If both those specs pass, my app will still be broken, because the method I stub out in the first spec doesn't have the same name as the one I make sure works in the second.
Now, one answer to this is "you need integration tests", but unless my integration tests are super thorough, I might miss an error like this one.
Is there any automated way to compare the methods I expect to be there in my controller tests, with the methods I actually test for in my model tests?
It now looks like there's an extension to Rspec called rspec-fire which claims to help with this. I haven't tried it yet but wanted to document it here for others.
I also want to link to this talk, because it has an awesome title: http://www.infoq.com/presentations/integration-tests-scam
I am using ruby on rails 3. I have a model called Content. Within the controller, I extract some variables and pass them to the Viewer. In the Viewer, I would like to use of my self made functions so that I don't have too much logic and code in the Viewer. I defined these functions in the ContentsHelper module.
My functions defined in the ContentsHelper module are making use of ActionViewer helper functions, however these are not available in the ContentsHelper module. I am getting for example NoMethodError: undefined method content_tag' for #<Content:0x1025b9458> error.
How is it possible to make all the ActionViewer helper functions available?
Newbie.
following suggestion of Tim:
module ContentsHelper
include ActionView::Helpers
def bla
content_tag(:h2, self.title)
end
I can run the bla method as Content.bla in the console. This is perfect!
But when I replacec content_tag with image_tag, then I run into trouble and get this error:
NoMethodError: undefined method `config'
from /Users/sonat/.rvm/gems/ruby-1.8.7-p334/gems/activemodel-3.0.0/lib/active_model/attribute_methods.rb:364:in `method_missing'
from /Users/sonat/.rvm/gems/ruby-1.8.7-p334/gems/activerecord-3.0.0/lib/active_record/attribute_methods.rb:46:in `method_missing'
from /Users/sonat/.rvm/gems/ruby-1.8.7-p334/gems/activerecord-3.0.0/lib/active_record/attribute_methods.rb:44:in `send'
I can see that module that is responsible of the image_tag method is missing "something". I would appreciate if you guys tell me the general approach in finding what is missing and how I could solve the problem.
Looks like you're trying to do something odd like to use the helper method inside your model instead of inside your view. Helper methods are for views, not for models.
Added
Tim asked if I could provide some links to other resources, but really this is such basic stuff that I'm not aware of anything dealing with this. Mostly tutorials deal with unusual things like using helpers outside views.
So instead, here's some code:
app/helpers/contents_helper.rb
module ContentsHelper
def foo
content_tag :p, "Foo"
end
end
app/views/contents/index.html.erb
<h1>Listing Contents</h1>
<%= foo %>
The HTML output when going to /contents URL
<h1>Listing Contents</h1>
<p>Foo</p>
And that's as hard as it is.
content_tag:
Does this work?
module ContentsHelper
include ActionView::Helpers
end
image_tag:
Looks like you'll have to make your models know where the images are located by implementing a #path_to_image(image) method.
I've set up a Gist for us to mock out the features you need here:
https://gist.github.com/1015333
You should be able to download and run forNoNameNo.rb (which should run quietly without errors.)
That file has some examples of what's needed to make image_tag work.
further discussion:
Helpers are probably the weirdest part of Rails. They're declared at the controller level, but are only included at the view level, and rely on weird parts of the controller stack for their info; and yet, the info they are mainly concerned with presenting is the model info. So they're spread across all these weird concerns.
To deal with code-organizations issues arising from all of this, people have tended toward the Presenter pattern. (Also see rbates' version)
That said, if you'd prefer to stray off the beaten path in rails, it's normally really useful to read the source code.
If you're using textmate:
mate `gem which actionpack`../action_view
in Terminal.app should get your there. If you're using another editor/operating system you might have to navigate to whereever gem which actionpack tells you to go.
I'm trying to extract some common code into a gem.
I'm thinking that acts_as_somethingis a good strategy for simple re-use.
Is there a good tutorial that discusses this for rails3 gems? I've found several that discuss rails2 (such as http://guides.rubyonrails.org/plugins.html) but that is specific to rails2
here are some of the tutorials/blogs I've already read:
http://guides.rubyonrails.org/plugins.html
http://www.thoughtsincomputation.com/categories/coding-gems-for-rails-3-tutorials (this is an excellent start but doesn't cover the act_as_* issue or controllers)
thanks
UPDATE: I've added a blog post based on this answer, but with much more detail: http://thoughtsincomputation.com/posts/coding-an-acts_as-gem-for-rails-3
--
I'm not aware of another tutorial source off the top of my head, but here are some general tips.
Rails 3 makes use of a really useful feature called Railtie - see http://api.rubyonrails.org/classes/Rails/Railtie.html .
So, if I were implementing an acts_as_* gem, I'd start there. My railtie might look something like:
# lib/acts_as_awesome/railtie.rb
require 'rails'
require 'acts_as_awesome'
module ActsAsAwesome
class Railtie < Rails::Railtie
config.to_prepare do
ApplicationController.send(:extend, ActsAsAwesome::Hook)
end
end
end
and the ActsAsAwesome::Hook code:
# lib/acts_as_awesome/hook.rb
module ActsAsAwesome::Hook
def acts_as_awesome(*args)
options = args.extract_options!
# do the things that make the controller awesome.
include ActsAsAwesome::InstanceMethods
before_filter :an_awesome_filter
end
end
I feel the concepts here are sound and have used similar processes before. Basically, it would tell Rails to execute the to_prepare block once during production and before each request in development (we want that because ApplicationController will be reloaded at those times, potentially wiping out our hook method); and the hook is just that: it adds a hook to all controllers (or rather, all controllers that extend ApplicationController) to allow the user to introduce the real "Awesome" code into their controllers without otherwise affecting controllers that don't need it.
The #acts_as_awesome hook doesn't, in itself, convey the Awesome functionality. That's because not all controllers might need this functionality. Instead, the method is responsible for introducing the real awesome stuff, via the ActsAsAwesome::InstanceMethods module. This way, the user only gets the Awesome functionality if they explicitly call the acts_as_awesome method. It also adds a before filter to the controller to demonstrate that the code in this method would be evaluated exactly the same as if it were in the target controller class itself.
This technique should work exactly the same if you're targeting models instead of controllers: just inject your hook into ActiveRecord::Base. As AR:B is only loaded at Rails boot, you should probably be able to put that into an initializer (refer to the Railtie docs), but I reserve the right to be mistaken here.
A gotcha concerning the railtie: the documentation reads as if it should have been autodetected, but I often have problems with this. To get around it, simply require the railtie from your gem's main source file (in the above example, that would be lib/acts_as_awesome.rb).
You can see the entire ActsAsAwesome source in all its glory at my github account:
http://github.com/sinisterchipmunk/acts_as_awesome
I hope this is helpful. Your question was somewhat high-level so a high-level response is the best I can do.
-Colin MacKenzie IV
http://thoughtsincomputation.com
#sinisterchipmnk