This is my first on StackOverflow and I'm a new rails developer.
I'm using RoR to create an inventory application for Magic: The Gathering cards. I've found a Json API that I'd like to use to pull data on all of the cards, sets, etc into a local database.
My initial inclination is to create a helper class to manage all of this (which can also be called in seeds.rb during db:setup), but I have no idea where I should put this class in my project's directory structure. It's not really a model/controller/view, so I feel it should be kept separate from those parts of the app.
Further more, I'm having trouble testing any class I do make. I initially created a directory app/classes and put the class there. Then in my spec directory, I created spec/classes and created the spec file. Accessing my helper class from the spec did not work in the same way that accessing my models in their spec classes did.
I'm at a loss as to how to do this and quite a bit of googling and searching on here has just left me more confused. I'd love any help that can be offered. How would you do this?
You don't mention specifically what issues you're encountering, but for starters app/classes isn't in rails's autoload path - rails' require magic doesn't know to look in there to find these classes (as an aside, 'classes' sounds like a slightly meaningless name - models & controllers are classes too).
You can add to the paths rails searches (see config.autoload_paths in config/application.rb) but I would put this in lib (and the corresponding specs in spec/lib).
It would also work just fine with these classes in app/models, whether or not it does there is down to choice. There's nothing that says that files in there have to be active record subclasses - the decision of whether or not this functionality belongs in there boils down to whether it works/feels like a model to you.
Related
Background
We are using these locations as per the Rails standard:
app/models for models (including app/models/concerns to avoid the app/models/*.rb files getting too fat)
app/controllers (including concerns) for lean controllers
app/views as usual
app/view_models for "view models" (Ruby code that is specific to an association between a view and a model, but cannot really exist separately, so cannot really be put into the model or the view)
lib for code that is not calling into app, but is called from app; for things that are really not domain-specific to our application. These are potential candidates for getting extracted into their own gems, if they were to be re-used in other apps.
So far so good, I believe this is all pretty common.
Problem
There is one specific type of code that I am not really sure where to put. This is code related to importing data. This may, for example, be code which processes some XML and does several different actions on the models, but may also be things like code parsing an Excel file, or a class that pulls data from some webservice). Let's see where we could put that:
app/models/concerns - this is where we have that now. But that code is not really representing a model; it is representing a state-changing XML (in this example). It will strongly interact with models, but is not themselves a model; a strong expectation for us is that code in app/models is often used by other classes (i.e., by controllers, views...), but the kind of code we are talking about now is not really doing that.
app/controllers - the part that does any actual file handling and such lives there, this is OK. The processing of the XML data structures does not belong there.
app/views - nope.
lib - nope. The handling of the XML in this example is very domain/app specific.
Question
Where do you put such code? Do you have an app/import subtree? Does it live in the models?
I liked your approach of architecture and folder structure, so couldn't get past your post :)
I think, that app subfolder is definitely the correct place to keep such classes. In our projects we have app/services, app/decorators, app/facades (as an another realization of view_models that we took from Sandi Metz).
Several weeks ago we faced the very same logic, as you and we decided to store it in app/parsers. In your case I would think about app/importers or smth like this.
So my general opinion is that your initial direction is correct for sure.
I'm wondering if there are any best practices about where to put non-standard Ruby files in Rails apps, those that don't fit in any of the default directories (controllers/models etc.).
I'm talking about classes that are used by controllers/models etc., but are not subclasses of any of the Rails base classes. Classes that include functionality extracted from models to make them less fat. Some of them kind of look like models but aren't AR models, some of them look more like "services", some are something in between or something else.
A few random examples:
"strategy" classes that handle authentication with password, via facebook etc.
"XParams" objects that encapsulate params or "XCreator" objects that handle processing of params to execute some complex action that results in creating some AR models in the end
classes that make requests to external APIs or encapsulate those requests and responses
fake models that can be substituted for a real AR model (e.g. guest user)
Resque jobs
classes that store and read information from Redis
classes that execute some specific actions like processing data, generating reports etc. and are called from Resque jobs or rake tasks
I've got quite a lot of these now, some of them are added to lib which ends up as a pile of random classes and modules, some sneak into app/models. I'd like to organize this somehow, but I don't know where to start.
Should only AR models go into app/models? Or is it ok to also put there any domain or helper models? How you decide if something is a model?
Should everything that doesn't fit into app go into lib? Or maybe I should add a few new custom subdirectories to app? What subdirectories, and how do I divide the custom classes?
How do you handle this in your projects? I know every project is a bit different, but there must be some similarities.
Good question - i don't have a concrete answer for you
but I recommend checking out this post
- http://blog.codeclimate.com/blog/2012/02/07/what-code-goes-in-the-lib-directory/
- be sure to read through all the comments
on a current project i have a ton of non-ActiveRecord objects under app/models, it works but not ideal
i put 're-useable' non application specific code under lib
other alternatives I have tried on side projects (say we have a bunch of command objects)
rails is a pain when it comes to namespaces under app, it loads everything up into the same namespace by default
app/
commands/
products/create_command.rb # Products::CreateCommand
products/update_price_command.rb # Products::UpdatePriceCommand
alternate, everything besides rails under src or an app_name directory
app/
src/
commands/
create_product.rb # Commands::CreateProduct
update_product_price.rb # Commands::UpdateProductPrice
I haven't come across a good solution for this, ideally the 2nd one is better, but would be nice to not have the additional directory under app, that way you open app and see controllers, commands, models etc...
You touch on a number of different use cases, and I think that this part is the closest to the "right" answer:
I've got quite a lot of these now, some of them are added to lib which ends up as a pile of random classes and modules, some sneak into app/models. I'd like to organize this somehow, but I don't know where to start.
That's pretty much right on in my book. The one thing you don't mention is extracting various pieces into separate gems. Classes that talk to external services are excellent candidates for extraction, as are strategy classes if they're sufficiently general. These can be private, since running your own gem server isn't hard, and you can then obviously reuse them across ROR apps.
Last and most concretely, resque jobs I stuff into lib/jobs.
My rule of thumb is if it's a model of some kind, it goes into app/models. If not, it probably belongs in lib or some appropriately named subdirectory thereof, e.g. lib/jobs, lib/extensions, lib/external, or the like.
If you're interested, I also wrote a follow-up article about this a bit later summing up what I found: http://blog.lunarlogic.io/2013/declutter-lib-directory/
I place any model classes (like STI subclasses) in apps/models. I place my other classes in lib, as it seems to be the best place to put them. It's easy for me to know where to look. It's also easier for me to group my tests since my model classes are all in one place.
Convention-wise I'm loathe to put helper classes in app/models. If they're presenter classes they belong in the app/helpers. If they're not then lib seems to be the best place for them.
Often my classes find their way into lib in subdirectories where modules with the same name as the subdirectory is responsible for including them. (Rails is very touchy about filenames and classnames when it comes to the autoloader.)
Another option is to encapsulate each module into its own gem and then refer to the gem via your Gemfile. This permits code sharing across projects.
I'm just starting out in Rails and there's a lot I still need to learn so I'm likely to be on Stackoverflow more often than normal asking beginner Rails / Ruby questions.
I'm just trying to figure out how Helpers work in Rails. From what I've seen so far, Helpers are intended to be used with Views and not so much with your Controllers.
However I would like to make a simple function that will validate the user input given in params (check if certain params are defined and optionally check if their value is valid).
Can anyone explain to me what would be the best way of implementing this? (Keeping in mind that I will want to use this in many different controllers so it should be globally available.)
I also noticed that by default Rails does not generate a lib folder in the main application folder. Are developers to place their libs outside the app folder in the main folder, or does Rails use libraries differently?
With regards to your validation issue, it depends on what you are validating.
If the data makes up objects from your problem domain, also known as models, then you should use the built in validators from ActiveModel. This is probably what you should do, but its hard to say without knowing the exact problem. See the Rails Guides on Validations. You can tell if this is the case by asking yourself if the data that needs validation will be stored after you get it. If so, its most definitely a model. An example of this kind of data would be the title and text fields of a blog post being sent to Rails from a browser form.
If the data is something tertiary to your models, or specific to presentation, then you should be fine using helpers. You noticed that helpers are used mostly in the views, and although this is true, theres nothing stopping you from using them in the controllers, you just have to declare that you will use them using the ActiveController#helper method. Inside the ApplicationController class, a lot of devs will put helper :all to just include all the helpers in all the controllers. Once the code has been required once, it doesn't really incur that big a performance hit.
Do note that almost all incoming data can be modeled using a model. A big school of thought in the Rails world subscribes to the Fat Model idea. People say that putting as much code as possible in the model and as little in the controller as possible separates concerns properly and leads to more maintainable code. This suggests that even if you don't think the incoming data is modelable (in the sense that you can create a model to represent it), you should try to make it a model and encapsulate the logic around validating it. However, you may find that making a helper function is faster, and either will work.
Your notion of validating user input is a good one. I get the feeling that as you are new to Rails you are used to doing these things yourself, but that doesn't quite apply here. In the Rails world, a lot of the common stuff like validations is handled by the framework. You don't have to check for presence in the params array, instead you call validates_presence_of on the model and let Rails spit the error out to the user. It makes things easier in the long run if you let the framework do what it is designed to.
With regards to your question about the lib folder, it doesn't really matter. You can put miscellaneous support files and libraries in the lib folder in the root directory and they will be available for use in your application (the files in the app folder). You can also choose to abstract your code into a plugin or a gem and include it that way, which a lot of people opt to do. My suggestion for this would be to read up on the notion of gems and plugins before diving in.
Want you want is probably a custom validator (in Rails3):
http://railscasts.com/episodes/211-validations-in-rails-3
You can either add libs in a lib folder you create, or add them to config/initializers in a file you add. Files in the initializers directory are automatically loaded by Rails.
I have a model that requires loading external data from an auxiliary source. A number of web services exist that my model can fetch the data from (swappable), but I don't want to create code that will make it difficult to change services (costs significantly differ based on variable and fixed usage and it is likely changing will be required).
I would like to create a driver to perform the interaction (and then create further custom drivers if the service requires switching). Unfortunately, due to the tight coupling of the driver and model, it does not makes sense to extract the code into a plugin or gem. I have extracted all the code into a module (see example), and currently have the code declared above my model.
module Synchronize
def refresh
self.attributes = ...
self.save
end
end
class Data < ActiveRecord::Base
include Synchronize
end
Does Rails (3.0.0) have a convention for storing modules tightly coupled with models? Should I be using a plugin to do this? Is this associated with the 'app/helpers' directory? If not, where is the most appropriate place to store the code? Thanks!
You are correct that if the module is tightly coupled to that specific model then it's not a good candidate for a gem/plugin.
app/helpers/ is for view helper methods and shouldn't contain modules that are solely for mixing into models.
One place you could put the module is within lib/. This is for code that doesn't really fit anywhere within app/ and is often the initial home of loosely coupled code before it is moved to a plugin (but that isn't a hard and fast rule). However, since your module is tightly coupled to your model, lib/ may not be the best place for it.
I know that 37signals (and others) use the concept of 'concerns' as a way of keeping related model code organised in modules. This is implemented by creating app/concerns/ and putting the modules in there. That directory is then added to the app's load path in config/application.rb (config/environment.rb for Rails 2) with:
config.load_paths += %W(#{Rails.root}/app/concerns)
The module can then be mixed into the model as normal.
Here's the original blog post about this by Jamis Buck - http://weblog.jamisbuck.org/2007/1/17/concerns-in-activerecord
Another variation of this which I personally prefer, although it doesn't involve modules, uses this plugin:
http://github.com/jakehow/concerned_with
Hope that helps.
This link has helped me out around this.
http://ander.heroku.com/2010/12/14/concerns-in-rails-3/
I have been sticking it in a model/extensions directory. The concerns directory makes sense but the word 'concerns' doesn't feel obvious to me. Maybe it will grow on me.
I also added the extensions path in the application.rb
config.autoload_paths += %W(#{config.root}/app/models/extensions)
I have a model that requires loading external data from an auxiliary source. A number of web services exist that my model can fetch the data from (swappable), but I don't want to create code that will make it difficult to change services (costs significantly differ based on variable and fixed usage and it is likely changing will be required).
I would like to create a driver to perform the interaction (and then create further custom drivers if the service requires switching). Unfortunately, due to the tight coupling of the driver and model, it does not makes sense to extract the code into a plugin or gem. I have extracted all the code into a module (see example), and currently have the code declared above my model.
module Synchronize
def refresh
self.attributes = ...
self.save
end
end
class Data < ActiveRecord::Base
include Synchronize
end
Does Rails (3.0.0) have a convention for storing modules tightly coupled with models? Should I be using a plugin to do this? Is this associated with the 'app/helpers' directory? If not, where is the most appropriate place to store the code? Thanks!
You are correct that if the module is tightly coupled to that specific model then it's not a good candidate for a gem/plugin.
app/helpers/ is for view helper methods and shouldn't contain modules that are solely for mixing into models.
One place you could put the module is within lib/. This is for code that doesn't really fit anywhere within app/ and is often the initial home of loosely coupled code before it is moved to a plugin (but that isn't a hard and fast rule). However, since your module is tightly coupled to your model, lib/ may not be the best place for it.
I know that 37signals (and others) use the concept of 'concerns' as a way of keeping related model code organised in modules. This is implemented by creating app/concerns/ and putting the modules in there. That directory is then added to the app's load path in config/application.rb (config/environment.rb for Rails 2) with:
config.load_paths += %W(#{Rails.root}/app/concerns)
The module can then be mixed into the model as normal.
Here's the original blog post about this by Jamis Buck - http://weblog.jamisbuck.org/2007/1/17/concerns-in-activerecord
Another variation of this which I personally prefer, although it doesn't involve modules, uses this plugin:
http://github.com/jakehow/concerned_with
Hope that helps.
This link has helped me out around this.
http://ander.heroku.com/2010/12/14/concerns-in-rails-3/
I have been sticking it in a model/extensions directory. The concerns directory makes sense but the word 'concerns' doesn't feel obvious to me. Maybe it will grow on me.
I also added the extensions path in the application.rb
config.autoload_paths += %W(#{config.root}/app/models/extensions)