From: Adam Akhtar <adamtemporary@...>
Date: 2009-04-06T10:13:54+09:00
Subject: how to dynamically create search term for array.find_all

i want to be able to create a mehtod that will filter results in an
array. The conditions are known at run time so id like to be able to do
it on the fly / dynamically.

e.g. user wants to filter results in array so that only results which
have the following categories are returned

:scifi
:comedy
:horror

id like that to be placed into a Array.find_all call like below


some_array.find_by {|x| x.category == :scifi OR x.category == :horror OR
x.category == :comedy}

how do i write the {....} bit if i dont know in advance exactly how many
/ which cateogries will be requested?

I know i could take hte users selections and put them in an array and do
this

filtered_results = []

users_filter_choices.each do |filter|
filtered_results += all_results.find_all{|x| x.category == filter
end

i dont know but is that bad for performance?
Also it assumes that the conditions must == , what happens if i want
less than or more thans in there for numerical attributes?
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