Rails: FakeModel runs the same validation too many times - ruby-on-rails

We have created a FakeModel object class which inherits from Object,
to allow working with models who don't have a DB table.
It has the basic functionality of a regular ActiveRecord model.
We also added in the class the following line:
include ActiveRecord::Validations
The problem is this:
A new request is sent to the controller, and creates a new object inheriting from the FakeModel class.
When the validations of that object run, they run more then once.
Too be more specific - with each request sent to the server,
the validations run one time more than the last request.
I'm guessing something here "sticks" on the server-level
(of course, when I restart the server, it resets back to running the validations just once)
What can be the cause of that?
UPDATE :
The ActiveModel solution isn't possible for me because I'm using Rails 2.3.8. I still need to figure out where is the problem.

I would suggest you to use ActiveModel instead of writing your own Model engine from scratch, see this blog post for a tutorial you can also watch this screencast

I'm stabbing the dark here, but it sounds like the validations keep being included every time the model is loaded/saved.
Can you show us where you include it?
In Hyperactive Resource, instead of include we used:
# make validations work just like ActiveRecord by pulling them in directly
require "active_record/validations.rb"
extend ActiveRecord::Validations::ClassMethods

Related

Rails ActiveRecord override default find

I'm building an API wrapper that will query objects from a third-party API and build them into objects to be used in my Rails environment. To do that, I'm building a set of models that use ActiveRecord (for some of its functionality) but are not database backed. I would like to be able to make a call like this:
obj = MyModel.find(1)
And have the code be something like this:
def MyModel.find id
# check for object in cache
# check for object in db
# grab object from API
# return object
end
Am I going to do something horribly wrong if I override the default find method? Am I approaching this in totally the wrong way?
If you are not using a database, then you do not need ActiveRecord. The entire purpose of ActiveRecord is to give you a mapping to a relational database.
I think what you want is for a class to implement certain pieces of what ActiveRecord provides, and Rails 3 has made those pieces into classes that you can include into regular 'ol classes on an as-needed basis. Look at this article for more details: http://www.rubyinside.com/rails-3-0s-activemodel-how-to-give-ruby-classes-some-activerecord-magic-2937.html
For instance, if you only want validations on a class, you can use include ActiveModel::Validations and then you'll get all of the nice error handling and .valid? and validates presence: true kind of behavior you're used to.
I would also suggest the railscast by Ryan Bates: http://railscasts.com/episodes/219-active-model which goes into more detail.

Rails create! using wrong class

I have two models Plan and Student::Plan. When calling Student::Plan.create! in my seeds.rb file I get back a Plan object. It seems as though rails is getting confused by the namespacing or something. Any thoughts that don't involve renaming the class?
file structure
models
plan.rb
student
plan.rb
tables
plans
student_plans
Update
This gets even weirder when testing w/ rails c. If you call Student::Plan.create! first then you'll get the expected object back. If you instead call Plan.create! and then Student::Plan.create! you'll be back a Plan object instead of what you'd actually expect.
Works
Student::Plan.create # <Student::Plan...>
Doesn't Work
Plan.create # <Plan...>
Student::Plan.create # <Plan...>
I can imagine a scenario where you have namespaced models (I've used it a few times...usually for integrating different db's). And this answer doesn't get to the issue of dealing with namespacing issues, but I do think the "Judo" solution is to just create a model called student_plan.rb at the root of the models directory, and use StudentPlan.create and Plan.create respectively.

accessing current_user in model; has to be a better way for logging and auth

I know the dogma says to not access current_user in a model but I don't fully agree with it. For example, I want to write a set of logging functions when an action happens via a rails callback. Or simply writing who wrote a change when an object can have multiple people write to it (not like a message which has a single owner). In many ways, I see current_user more as config for an application - in other words make this app respond to this user. I would rather have my logging via the model DSL rather than in the action where it seems REALLY out of place. What am I missing?
This idea seems rather inelegant Access current_user in model
as does this: http://rails-bestpractices.com/posts/47-fetch-current-user-in-models
thx
edit #1
So my question isn't if there are gems that can do auditing / logging. I currently use paper_trail (although moving away from it because I can do same functionality in approx 10 lines of ruby code); it is more about whether current_user should never be accessed in the model - I essentially want to REDUCE my controller code and push down logic to models where it should be. Part of this might be due to the history of ActiveRecord which is essentially a wrapper around database tables for which RoR has added a lot of functionality over the years.
You've given several examples that you'd like to accomplish, I'll go through the solution to each one separately:
I want to write a set of logging functions when an action happens via
a rails callback
Depending on how you want to log (DB vs writing to the logger). If you want to log to the DB, you should have a separate logging model which is given the appropriate information from the controller, or simply with a belongs_to :user type setup. If you want to write to the logger, you should create a method in your application controller which you can call from your create and update methods (or whatever other actions you wanted to have a callback on.)
Or simply writing who wrote a change when an object can have multiple people write to it
class Foo < ActiveRecord::Base
belongs_to :user, as: :edited_by
end
class FooController < ApplicationController
def update
#foo = Foo.find(params[:id])
#foo.attributes = params[:foo]
#foo.edited_by = current_user
end
end
I think you're misunderstanding what the model in Rails does. Its scope is the database. The reason it can't access current_user, is because the current user is not stored in the database, it is a session variable. This has absolutely nothing to do with the model, as this is something that can not exist without a browser.
ActiveRecord::Base is not a class that is designed to work with the browser, it is something that works with the database and only the database. You are using the browser as an interface to that model, but that layer is what needs to access browser specific things such as session variables, as your model is extending a class that is literally incapable of doing so.
This is not a dogma or style choice. This is a fact of the limitations of the class your model is extending from. That means your options basically boil down to extending from something else, handling it in your controller layer, or passing it to the model from your controller layer. ActiveRecord will not do what you want in this case.
The two links you show (each showing imho the same approach) is very similar to a approach I still use. I store the current_user somewhere (indeed thread-context is the safest), and in an observer I can then create a kind of audit-log of all changes to the watched models, and still log the user.
This is imho a really clean approach.
An alternative method, which is more explicit, less clean but more MVC, is that you let the controller create the audit-log, effectively logging the actions of the users, and less the effects on different models. This might also be useful, and in one website we did both. In a controller you know the current-user, and you know the action, but it is more verbose.
I believe your concerns are that somehow this proposed solution is not good enough, or not MVC enough, or ... what?
Another related question: How to create a full Audit log in Rails for every table?
Also check out the audited gem, which solves this problem as well very cleanly.
Hope this helps.

Rails: Tableless model that calls other models

I have a Rails app with a few model classes (e.g. Category, Subcategory, User, etc.). In order to implement a not-too-trivial filter functionality, I built a hierarchy of filter classes: FilterCategory, FilterSubcategory, etc., that derive from FilterBase. Each of them uses the appropriate "sister" model class (e.g. Category.find :all).
I quickly realized that I can't simply call the "sister" model class without using "require" first. However, I now suspect that using "require" is the main reason for two other problems I posted here and here, which probably mess up the class caching when config.cache_classes=false.
Is there another way for me to call these other models without requiring them?
I tried using the BaseWithoutTable plugin, but when I call the "sister model", I end up getting "Not a valid constant descriptor: nil", which occurs since Rails looks for "FilterCategory::Category" rather than "Category".
Any thoughts of the best way to do that?
I'm using Rails 2.3.8, Ruby 1.8.7.
Thanks,
Amit
I wonder if you want ::Category - getting Category from the top-level namespace rather than scoping it to FilterCategory?
If your models are in the app/models directory, you shouldn't need to explicitly require them - Rails already takes care of that.

Rails 3 loading all models on startup

I have a class method mixed in to all my models. the method gets called when the model class is evaluated. unfortunately (for me), this seems to be on-demand, whenever the model is needed in development env. how can have rails load all the models at start up? is this even advisable?
class Foo < ActiveRecord::Base
include Acl
register_acl # i need this to be called for all models at start up
end
Basically, the register_acl takes a few arguments of "actions" that the model would like to be access controlled. Suppose one of the action of Foo is "manage" and the system needs to be aware of this action at start up. I think in the model is the most natural place to have this logic.
thank you!
The correct way to do this application-wide is to turn on cache_classes in your configuration. By default it's off in development but on in production.
If you want to do it sporadically:
Rails.application.eager_load!
I dont know if this is ideal, but it works for me. Somewhere in the config/initialize/, i do this:
Dir.glob("#{Rails.root}/app/models/*.rb").sort.each { |file| require_dependency file }
and that preloads my models
In MVC concept models are not intended to act by themselves, i.e. they should only act when controller sends them a message (for example, #foo.register_acl). Model instances even should not exist until they are created by controller.
What are you trying to achieve with your register_acl method?
If you really need something to be executed on object creation you can use initialize() method which is called whenever a Ruby object is created.
However if you need model to execute some code by itself you are most likely facing some code smell and you need to change something within your app.

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