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A Rails mixin to make inquiries with lookup tables, e.g. when used in association
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# Mix this into an AR class for lookup tables to perform an inquiry. | |
# For example, if Movie has Genre and genres table has id->genre mapping | |
# then one could use the_movie.genre.comedy? instead of the_movie.genre.genre == 'comedy' | |
module LookupTable | |
def self.included(base) | |
raise "#{name} can only be included into classes that inherit from ActiveRecord::Base, #{base.name} does not." unless base < ActiveRecord::Base | |
base.instance_variable_set :@lookup_column, base.name.demodulize.underscore | |
base.extend(ClassMethods) | |
end | |
module ClassMethods | |
attr_reader :lookup_column | |
# Reverse find | |
def rfind(value) | |
where(lookup_column => value).take | |
end | |
end | |
private | |
def respond_to_missing?(method_name, include_private = false) | |
(method_name[-1] == "?") || super | |
end | |
def method_missing(method_name, *arguments) | |
if method_name.to_s[-1, 1] == "?" | |
val = read_attribute self.class.lookup_column | |
val == method_name.to_s[0..-2] | |
else | |
super | |
end | |
end | |
end |
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