Overriding “find” in ActiveRecord the DRY way
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09-06-2019 - |
Question
I have a few models that need to have custom find conditions placed on them. For example, if I have a Contact model, every time Contact.find is called, I want to restrict the contacts returned that only belong to the Account in use.
I found this via Google (which I've customized a little):
def self.find(*args)
with_scope(:find => { :conditions => "account_id = #{$account.id}" }) do
super(*args)
end
end
This works great, except for a few occasions where account_id is ambiguous so I adapted it to:
def self.find(*args)
with_scope(:find => { :conditions => "#{self.to_s.downcase.pluralize}.account_id = #{$account.id}" }) do
super(*args)
end
end
This also works great, however, I want it to be DRY. Now I have a few different models that I want this kind of function to be used. What is the best way to do this?
When you answer, please include the code to help our minds grasp the metaprogramming Ruby-fu.
(I'm using Rails v2.1)
Solution
You don't tell us which version of rails you are using [edit - it is on rails 2.1 thus following advice is fully operational], but I would recommand you use the following form instead of overloading find yourself :
account.contacts.find(...)
this will automatically wrap the find in a scope where the user clause is included (since you have the account_id I assume you have the account somewhere close)
I suggest you check the following resources on scopes
OTHER TIPS
Jean's advice is sound. Assuming your models look like this:
class Contact < ActiveRecord::Base
belongs_to :account
end
class Account < ActiveRecord::Base
has_many :contacts
end
You should be using the contacts
association of the current account to ensure that you're only getting Contact
records scoped to that account, like so:
@account.contacts
If you would like to add further conditions to your contacts query, you can specify them using find:
@account.contacts.find(:conditions => { :activated => true })
And if you find yourself constantly querying for activated users, you can refactor it into a named scope:
class Contact < ActiveRecord::Base
belongs_to :account
named_scope :activated, :conditions => { :activated => true }
end
Which you would then use like this:
@account.contacts.activated
to give a specific answer to your problem, I'd suggest moving the above mentioned method into a module to be included by the models in question; so you'd have
class Contact
include NarrowFind
...
end
PS. watch out for sql escaping of the account_id, you should probably use the :conditions=>[".... =?", $account_id]
syntax.