By convention, should the following be defined as an instance method of my model or a helper method?
# app/models/user.rb
class User < ActiveRecord::Base
def full_name
"#{first_name} #{last_name}"
end
end
or
# app/helpers/users_helper.rb
module UsersHelper
def full_name
"#{#user.first_name} #{#user.last_name}"
end
end
Many thanks.
Go with the first (keep in model), also because you might want to do other stuff, like combined indexes :)
Everything directly related to your model should stay in your model.
This way, you keep coherent logic and tests.
Related
I need to call a helper method within a model, from both a class and an instance method, e.g. Model.method(data) and model_instance.method. However, the class method always returns "NoMethodError: undefined method 'helper_method' for #<Class ...>"
model.rb:
class Model < ActiveRecord::Base
include ModelHelper
def method
helper_method(self.data)
end
def self.method(data)
self.helper_method(data)
end
end
model_helper.rb:
module ModelHelper
def helper_method(data)
# logic here
end
end
I even tried adding def self.helper_method(data) in the helper to no avail.
After quite a bit of seraching, I wasn't able to find anything on how to achieve this, or at least anything that worked.
The answer turned out to be pretty simple, and doesn't require any Rails magic: you just re-include the helper and define the class method within a class block:
class Model < ActiveRecord::Base
include ModelHelper
def method
helper_method(self.data)
end
# Expose Model.method()
class << self
include ModelHelper
def method(data)
helper_method(data)
end
end
end
No changes to the helper needed at all.
Now you can call method on both the class and an instance!
If there's no additional logic in method, then you can simply do:
class Model < ActiveRecord::Base
include ModelHelper
extend ModelHelper
end
And get both the instance (#model.helper_method) and the class (Model.helper_method) methods.
If, for legacy (or other) reasons, you still want to use method as an instance and class method, but method doesn't do anything different than helper_method, then you could do:
class Model < ActiveRecord::Base
include ModelHelper
extend ModelHelper
alias method helper_method
singleton_class.send(:alias_method, :method, :helper_method)
end
And now you can do #model.method and Model.method.
BTW, using modules to include methods in classes is seductive, but can get away from you quickly if you're not careful, leaving you doing a lot of #model.method(:foo).source_location, trying to figure out where something came from. Ask me how I know...
you need to define model_helper.rb as:
module ModelHelper
def self.helper_method(data)
# logic here
end
end
and call this method in model.rb as:
class Model < ActiveRecord::Base
include ModelHelper
def method
ModelHelper.helper_method(self.data)
end
def self.method(data)
ModelHelper.helper_method(data)
end
end
For example, if I have a method in my model that accepts a string from my controller. Am I able to call it elsewhere in my model, which would return the boolean value? Or is there a better way, possibly by setting a variable?
class Object
def method_true?(args)
['a', 'b'].include?(args)
end
def do_stuff
method_true? #outcome of method_true?
end
end
Patching Object class is not the best idea.
More Rails way would be creating a module with these methods and mixing it into your models (or, into ActiveRecord::Base, if you are sure you need it everywhere):
module ActiveRecordExtentions
def method_true?(args)
['a', 'b'].include?(args)
end
def do_stuff
method_true? #outcome of method_true?
end
end
# /initializers/activerecord_extentions.rb
ActiveRecord::Base.send(:include, ActiveRecordExtentions) # or extend, you decide
Now methods are available in all models inheriting from ActiveRecord::Base.
I'm using the callback before_update to call a function on model which set the checkbox value on my variable.
The problem is the checkbox value which is on params[:mail_checker_issue] isn't accessible on the model layer.
The question is: How to access this params using the callback before_update ? Below my code:
module IssueSetChecketIssuePatch
def self.included(base)
base.send(:include, InstanceMethods)
base.class_eval do
before_save :before_mail_checker
end
end
end
module InstanceMethods
require_dependency 'issue'
def before_mail_checker
self.set_mail_checker_issue(params[:mail_checker_issue])
end
def set_mail_checker_issue(mail)
#mail_checker = mail
end
def get_mail_checker_issue
#mail_checker
end
end
Rails.configuration.to_prepare do
Issue.send(:include, IssueSetChecketIssuePatch)
end
params are a controller concern and are wholly separate from models. Consider what should happen if you tried to save that model from a console, for example.
You need to pass the param to the model after you instantiate it from your controller, then check the value set on the model in your before_save callback.
It's also worth noting that your code is somewhat un-Rubyish (and really, looks a lot like Java!) - you could get the same effect by just defining an attr on the model.
Rails.configuration.to_prepare do
require_dependency 'issue'
class Issue
attr_accessor :mail_checker_issue
end
end
Then, once you have an issue:
# Controller code
#issue = Issue.find(params[:id])
#issue.mail_checker_issue = params[:mail_checker_issue]
You don't, models don't know about controllers or params hash.
You should include this logic at your controller instead of forcing it in a callback.
hi i am trying to access current_user within a model for the purpose of creating an element on the fly with find_or_create_by.
the following is the method within my model
def opponent_name=(name)
self.opponent = Opponent.find_or_create_by_name_and_team_id(name,current_user.team_id) if name.present?
end
but the error i am getting is
NameError in EventsController#create
undefined local variable or method `current_user' for #<Event:0x007fb575e92000>
current_user is not accessible from within model files in Rails, only controllers, views and helpers.
What you should do is to pass the current_user.team_id to the opponent_name method like this:
def opponent_name=(name, current_user_team_id)
self.opponent = Opponent.find_or_create_by_name_and_team_id(name,current_user.team_id) if name.present?
end
Access current_user in Model File:
# code in Applcation Controller:
class ApplicationController < ActionController::Base
before_filter :global_user
def global_user
Comment.user = current_user
end
end
#Code in your Model File :
class Comment < ActiveRecord::Base
cattr_accessor :user # it's accessible outside Comment
attr_accessible :commenter
def assign_user
self.commenter = self.user.name
end
end
Pardon me, if It violates any MVC Architecture Rules.
Its not a good way to access the current_user in a model, this logic belongs to the controller. But if you realy cant find a workaround you should put it into a thread. But keep in mind this is not the way how it should be build.
https://rails-bestpractices.com/posts/2010/08/23/fetch-current-user-in-models/
Rails 5.2 introduced current attributes:
https://api.rubyonrails.org/classes/ActiveSupport/CurrentAttributes.html
but as always... you must have in mind that using global states like this might let to some unpredictable behaviour 🤷♀️ :
https://ryanbigg.com/2017/06/current-considered-harmful
I wanted to add a method to two models, so I made a module like this and included it in both models.
module UserReputation
def check_something
...
end
end
That worked fine. I then wanted to have that method called as an :after_create on all those models. It works if I add it manually to all the models, but I wanted to be smart and include it in the module like this:
module UserReputation
after_create :check_something
def check_something
...
end
end
But this doesn't work. Is there any way to accomplish this and DRY up the after_create as well?
Try self.included, which is called when the module is mixed into the class base:
module UserReputation
def self.included(base)
base.after_create :check_something
end
end