Implementing an ActiveRecord before_find
-
03-07-2019 - |
Question
I am building a search with the keywords cached in a table. Before a user-inputted keyword is looked up in the table, it is normalized. For example, some punctuation like '-' is removed and the casing is standardized. The normalized keyword is then used to find fetch the search results.
I am currently handling the normalization in the controller with a before_filter. I was wondering if there was a way to do this in the model instead. Something conceptually like a "before_find" callback would work although that wouldn't make sense on for an instance level.
Solution
You should be using named scopes:
class Whatever < ActiveRecord::Base
named_scope :search, lambda {|*keywords|
{:conditions => {:keyword => normalize_keywords(keywords)}}}
def self.normalize_keywords(keywords)
# Work your magic here
end
end
Using named scopes will allow you to chain with other scopes, and is really the way to go using Rails 3.
OTHER TIPS
You probably don't want to implement this by overriding find. Overriding something like find will probably be a headache down the line.
You could create a class method that does what you need however, something like:
class MyTable < ActiveRecord::Base
def self.find_using_dirty_keywords(*args)
#Cleanup input
#Call to actual find
end
end
If you really want to overload find you can do it this way:
As an example:
class MyTable < ActiveRecord::Base
def self.find(*args)
#work your magic here
super(args,you,want,to,pass)
end
end
For more info on subclassing checkout this link: Ruby Tips
much like the above, you can also use an alias_method_chain
.
class YourModel < ActiveRecord::Base
class << self
def find_with_condition_cleansing(*args)
#modify your args
find_without_condition_cleansing(*args)
end
alias_method_chain :find, :condition_cleansing
end
end