I am implementing strategy pattern in Rails where I have Models like User, Item, Category and need to recommend items for the users depending on various algorithms (strategies) that user selects in view.
I am having a Recommend class which has an interface of recommend(user_id, strategy) and returns array of item_id. The strategy in recommend will be decided at runtime depending on the option user selects in the view. I have placed the recommend interface in /lib directory and the strategies in /lib/strategy directory.
I want to make sure if I placed the files in proper directories or Should I need place the recommend class and all the strategies in models or any where else. I am really confused.
In Rails all domain-specific code belongs in /app, whereas /lib is reserved for external dependencies and shared code.
You might find "service objects" useful, they belong in /app/services. They are not ActiveRecord classes and have no database, they generally work (perform services) with other models.
You'll find lots of info on how to construct services e.g. http://sporto.github.io/blog/2012/11/15/a-pattern-for-service-objects-in-rails/. There is also an excellent Railscast (subscribers only) http://railscasts.com/episodes/398-service-objects.
Related
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.
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 have a Rails app with the usual application_controller, and a controller (and model) for each of the tables. I also added a pages_controller, for the additional web pages my app uses, this is merely an empty method supporting the corresponding views.
Now I would like to add some methods and pages that provide some overall monthly stats for the app, pulling data from each of the tables, grouped by month.
Where does Rails convention say I should put these methods?
Thank you.
I'm not sure there's enough info here to create meaningful answers.
If you want model-specific stats, a module/mixin might make sense. It would provide normalized access to model-specific data. Depending on what you actually need, each model could have specific stat presentation layers.
There are many ways to implement this, but the code itself would likely live in a namespaced lib directory (if you're asking specifically about physical location).
You could either add the stats logic to your model, if you have a separated model for stats. Or you can create some class to handle that for you, therefor this file should be in lib/.
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)