Searching based on the return values of instance methods

Can I use something like searchlogic to search for objects based on
the return values of instance methods? E.g., I’d like to search for
users of a certain “age” but age is not a column, it’s an instance
method, returning the age value calculated from the birthdate, which
is a column.

Is there a quick way like searchlogic to do this or do I have to build
my own search queries? Thanks.

Converting to datetime object is an excellent idea. Thanks Jarin!

For that particular search, you’ll have to build your own search
queries. The only other option is to load all records into memory and
filter by the age instance method, but of course you don’t want to do

Searchlogic will still make the search easier though. You can convert
the age from an integer into a datetime object and use it in a
Searchlogic search like so:

age = 29

User.birthdate_greater_than(age.years.ago).birthdate_less_than((age -

Hope this helps!

Jarin U.
Robot Mode LLC

marikka! awesome. Thanks for sharing.

Thanks Jarin for the idea!

I used named scopes in my user model like this:

named_scope :age_gt, lambda { |age| { :conditions => [‘birthdate < ?’,
age.to_i.years.ago] }}
named_scope :age_lt, lambda { |age| { :conditions => [‘birthdate > ?’,
age.to_i.years.ago] }}

now I don’t need to use a special query to achieve this.