Generating search conditions?

Could anyone tell me good options for generating search conditions.
Specifically I have parameters based on time (today, yesterday, etc)
and I want a private method in a model to generate a conditions
statement.
The only way I can think to do it is something like :

(pseudocode)
def gen_conditions(part)
if part == “today”
return “submitted at < date”
else if part ==“yesterday”
return “submitted at < date”
end
end

This would probably work, but I’m thinking there might be a better
way. Thanks for any advice.

JB

hi, i think “Chronic” is the library you’re looking for. check it at :
http://chronic.rubyforge.org/