I constantly need to use long class name like
SomeReallyLongModuleName::AnotherLongModuleName::YetAnotherLongClassName
in the project. I want to access this class by something like YALCN. Where it's the best to keep definition like
YALCN = SomeReallyLongModuleName::AnotherLongModuleName::YetAnotherLongClassName
And is it a common practice, or people constantly use fully-qualified long name?
If this is only for Rails console usage, I'd put them into /lib/aliases.rb or somewhere similar and require the file when needed.
You could make "local" aliases. Something like this:
class Another
YALCN = SomeReallyLongModuleName::AnotherLongModuleName::YetAnotherLongClassName
def do_something
YALCN.new # or whatever
end
end
To avoid problems with autoloading, I'd keep the short constants in the same place they're used.
And is it a common practice, or people constantly use fully-qualified long name?
I haven't seen this too often.
Related
I have a monkeypatched of ActiveRecord find with some business logic, for example:
# lib/core_extensions/active_record/finder_methods/finder.rb
module ActiveRecord
module FinderMethods
def find(*args)
return super if block_given?
#... business logic code => my_error_control = true
raise "My Error" if my_error_control
retorn = find_with_ids(*args)
end
end
end
retorn
I have not seen many examples like this, and this causes me a doubt:
Where should finder.rb be?
In this example, this file is in lib/core_extensions/... but if it contains business logic, I think finder.rb should lives in the folder app/core_extensions/ isn't it?
Edited, after Sergio Answer
things like this, are a bad practice?
# lib/core_extensions/nil_class/image_attributes.rb
# suport for product images attributes
class NilClass
def main_image(size,evita_video)
"/images/paperclip_missing/original/missing.png"
end
end
Where should finder.rb be?
Ultimately, it doesn't matter. It only matters that this code gets loaded. This mix of patching base libraries and adding business logic there looks like something that MUST be documented thoroughly (in the project's wiki or something like that). And if it is documented, then it doesn't matter. The code is where the documentation says it is.
That being out of the way, here's a design suggestion:
when user seeks a Family Family.find(params[family_id],session[:company_id]), this find will compare the company of the family result family.company witht the parameter
Why not do something like this:
family = current_company.families.find(params[:family_id])
where current_company can be defined as #current_company ||= Company.find(session[:company_id])
Here, if this company doesn't have this family, you'll get an exception.
Same effect*, only without any patching. Much more futureproof. You can even add a couple of rubocop rules to ensure that you never write a naked Family.find.
* it's not like you add that patch and rest of your code magically acquires super-powers. No. You still have to change all the finders, to pass that company id.
It's the first time I see such case :). I'd put it in app/core_extensions and check if live reloading works correctly with it. If not, I'd move it to lib/. (It's just a heuristic)
Edit:
Instead of extending NilClass I'd rather use regular NullObjects. It's really less surprising and easier to understand.
https://robots.thoughtbot.com/rails-refactoring-example-introduce-null-object
I am trying to create a section in my app where a user can update certain site wide attributes. An example is a sales tax percent. Even though this amount is relatively constant, it does change every few years.
Currently I have created a Globals model with attributes I want to keep track of. For example, to access these attributes where needed, I could simply do something like the following snippet.
(1+ Globals.first.sales_tax) * #item.total
What is the best way to handle variables that do not change often, and are applied site wide? If I use this method is there a way to limit the model to one record? A final but more sobering question.......Am I even on the right track?
Ok, so I've dealt with this before, as a design pattern, it is not the ideal way to do things IMO, but it can sometimes be the only way, especially if you don't have direct disk write access, as you would if deployed on Heroku. Here is the solution.
class Global < ActiveRecord::Base
validate :only_one
private
def only_one
if Global.count >= 1
errors.add :base, 'There can only be one global setting/your message here'
end
end
end
If you DO have direct disk access, you can create a YAML config file that you can read/write/dump to when a user edits a config variable.
For example, you could have a yaml file in config/locales/globals.yml
When you wanted to edit it, you could write
filepath = "#{Rails.root}/config/locales/globals.yml"
globals = YAML.load(File.read("#{Rails.root}/config/locales/globals.yml"))
globals.merge!({ sales_tax: 0.07 })
File.write(filepath) do |f|
f.write YAML.dump(globals)
end
More on the ruby yaml documentation
You could also use JSON, XML, or whatever markup language you want
It seems to me like you are pretty close, but depending on the data structure you end up with, I would change it to
(1+ Globals.last.sales_tax) * #item.total
and then build some type of interface that either:
Allows a user to create a new Globals object (perhaps duplicating the existing one) - the use case here being that there is some archive of when these things changed, although you could argue that this should really be a warehousing function (I'm not sure of the scope of your project).
Allows a user to update the existing Globals object using something like paper_trail to track the changes (in which case you might want validations like those presented by #Brian Wheeler).
Alternatively, you could pivot the Global object and instead use something like a kind or type column to delineate different values so that you would have:
(1+ Globals.where(kind: 'Colorado Sales Tax').last) * #item.total
and still build interfaces similar to the ones described above.
You can create a create a class and dump all your constants in it.
For instance:
class Global
#sales_tax = 0.9
def sales_tax
#sales_tax
end
end
and access it like:
Global.sales_tax
Or, you can define global variables something on the lines of this post
I want to use Cuisines like (Chinese, Indian, US) as constant values in my application which are defined in a config file. How can I set as constants and how can access in controllers?
This is explicitly not an answer to your question, but a suggestion that you look for alternatives. I think you would be far better off creating a database table with your cuisine names in it than to use constants. Leverage rails associations so that you can write nice readable code.
The problem with using constants is that under many circumstances, they aren't really constant. What happens if you want to add Japanese? What happens if you want to add Thai, but then 6 months later decide to drop it? What happens if you decide that Indian is too broad, and you want "Northern Indian" and "Southern Indian"?
With a database table, you can ensure that the class that are associated with those constants are always in a consistent state. When you need to get them all, they are just a line of code away with
my_cuisines = Cuisine.all
with nice built in iterators.
You can use gem 'settingslogic'
model settings.rb:
class Settings < Settingslogic
source "#{Rails.root}/config/settings.yml"
namespace Rails.env
end
then, use in controller:
Settings.cousines
First, consider what Marc Talbot said. Make sure that you really don't want a normal database model. If you're sure you want to use constants then continue on:
My preferred way to do this is with a pseudo-model.
In app/models/cuisine.rb
class Cuisine
# Should come before the constant declarations
def initialize(name)
#name = name
end
Mexican = new('Mexican')
Chinese = new('Chinese')
Indian = new('Indian')
def to_s
name
end
# other related methods
# like translations, descriptions, etc.
end
Then in the everywhere else in the app you can just reference Cuisine::Mexican or Cuisine::Indian
Also depending on how you are using it you might need a list of the cuisines.
class Cuisine
...
def self.all
[Mexican, Indian, Chinese, ...]
end
end
This technique keeps the code organized and keeps you from writing yet another initializer file.
Lets say that on top of my Rails app there is a bar with piece of text displayed - latest hot deal, scheduled downtime notfication, something like that. It's a single, on of a kind information that needs to be accessed on basically every request, and may be updated from time to time. What is the best way to achieve this?
What I'd like to do is some kind of permanent global variable (accessible from controllers).
It will be updated very rarely, so there's no problem if for some time after update there will be an inconsistency between workers.
On the other hand, it should be persistent in case of server fault (periodic backup is enough).
It will be accessed really often, so it should be as fast as possible - preferably stay in memory.
Also, it's only one of a kind, so I'd really prefer not to bloat the app with a dedicated database model.
Something like that is damn easy in Node.js for example, but I couldn't find a single way to achieve this in Rails. What shall I do?
EDIT
Thanks for the answers so far, but while they're inspiring, I think that I should stress out one key functionality that they're all missing. The variable should be editable inside the app and persistent. While it's possible to edit your variables, in case of server restart I'm back to the default - which is bad.
It really depends on what you are looking for. You could do something very simply by putting it in your application_controller.rb
class ApplicationController < ActionController::Base
def system_message
"Come buy our amazing .99 iphone chocolate bar apps, with 100% more gamification!"
end
end
That function (and string) is then accessible from any controller in your application. You could also specify something in the after_initialize block in your application.rb file.
config.after_initialize do
::MYTEXT = "MY SUPER AMAZING TEXT"
end
You could also create your own file under the initializers directory, which is preloaded in rails.
so siteAnnounce.rb
MYANNOUNCEMENT = "NOW LISTEN TO ME!"
You may also want to check out this Railscast video about site wide announcements
I would store it in the database and let caching take care of it.
I feel that global variables are fine, when appropriate, for code that needs to share that common value in many places but that is the code, not the the user view.
This is clearly true in this case as the OP has bolded 'editable by the app'. So I would have a view that lets the users enter it, it gets stored in a db table and then recalled as needed (as cached once used once).
Well I had faced a similar problem.
My problem was I needed a global variable in all the levels (MVC).
We went to use Memcache to store the variable.
May be you can go for a similar solution.
And as an added bonus you can change it throughout the program.
You could declare it as a constant in an initializer:
config/initialzers/foo.rb:
MYVARIABLE = 'some string'
Accessible from anywhere in your application as MYVARIABLE
Ok, so here's what I did. Instead of just putting the value to an initializer, I've made there a simple class that handles it. The variable itself is stored in a predefined file. Besides of reading the file upon the initialization, the class updates file when the value is changed, and also re-read the file periodically to maintain consistency across workers. I've also put there some basic JSON handling and backup functionality to make life easier.
For anyone interested, here's the important code:
class Pomegranate
def initialize
#delay = 30.minutes
#path = "db/pomegranate.json"
#valid = Time.now - 1
validate
end
def get(*p)
validate
p.inject(#data) {|object,key| object[key] if object}
end
def set(*p, q, v)
hash = p.inject(#data) {|object,key| object[key]||={}}
hash[q] = v
end
def save
#valid = Time.now + #delay
File.open(#path,"w") {|f| f.write(#data.to_json)}
end
private
def validate
if #valid < Time.now
#data = ActiveSupport::JSON.decode(File.read(#path)) rescue {}
#valid = Time.now + #delay
#valid = Time.now - 1 if #data.empty?
end
end
end
$pom = Pomegranate.new
Source:
Where to put Global variables in Rails 3
Try putting it in your applicaton.rb like this:
module MyAppName
class Application < Rails::Application
YOUR_GLOBAL_VAR = "test"
end
end
Then you can call it with the namespace in your controllers, views or whatever..
MyAppName::Application::YOUR_GLOBAL_VAR
Another alternative would be using something like settingslogic. With settingslogic, you just create a yml config file and a model (Settings.rb) that points to the config file. Then you can access these settings anywhere in your rails app with:
Settings.my_setting
I've started putting constants and variables like this in the configuration object, e.g.
TestApp::Application.config.foo = 'bar'
TestApp::Application.config.something = { :a => 1, :b => 2 }
I have a method in the following folder:
/lib/app_name/my_file.rb
/lib/app_name/other_file.rb
In my code, things look like this currently:
APP_NAME::OTHER_FILE.some_method?(APP_NAME::MY_FILE::A::B)
is there a way I can include this once in my code so I don't have to reference it like this?
Particularly I want to access the method 'some_method' and the enumerations in the class MY_FILE.
In ruby everything is an object, even classes.
So you can assign the classes (or modules) to variables in order to create a local shorthand, like this:
other = APP_NAME::OTHER_FILE
mine = APP_NAME::MY_FILE::A::B
other.some_method? mine
You already shouldn't need to pass the names of any classes/modules under which you are currently namespaced, so for example, you can drop the APP_NAME:: portion in those class names.
If you want to reduce the size of the class names even further, you either need to literally change your class names (assuming you named them badly) or do as Pablo says and just alias them to shorter names. And yes, you can 'require' them to get the aliases in a single line:
Create a file, for example, the way it's done in gems: lib/app_name.rb (in the case of a Gem, lib/gem_name.rb). Inside that:
require 'app_name/my_file'
require 'app_name/other_file'
And inside other_file.rb and my_file.rb, create your aliases:
class AppName::MyFile
...
end
AppName::MF = AppName::MyFile
So now you can just require 'app_name' and all the classes will be loaded, along with their aliases.
Then you can reference AppName::MF instead of AppName::MyFile.
PS: You're using some weird naming convention, by the way ;) APP_NAME::MY_FILE as a class name is odd. Class names should be camel-cased.