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module ActiveRecord
module DynamicMatchers #:nodoc:
def respond_to_missing?(name, include_private = false)
if self == Base
super
else
match = Method.match(self, name)
match && match.valid? || super
end
end
private
def method_missing(name, *arguments, &block)
match = Method.match(self, name)
if match && match.valid?
match.define
send(name, *arguments, &block)
else
super
end
end
class Method
@matchers = []
class << self
attr_reader :matchers
def match(model, name)
klass = matchers.find { |k| k.pattern.match?(name) }
klass.new(model, name) if klass
end
def pattern
@pattern ||= /\A#{prefix}_([_a-zA-Z]\w*)#{suffix}\Z/
end
def prefix
raise NotImplementedError
end
def suffix
""
end
end
attr_reader :model, :name, :attribute_names
def initialize(model, name)
@model = model
@name = name.to_s
@attribute_names = @name.match(self.class.pattern)[1].split("_and_")
@attribute_names.map! { |n| @model.attribute_aliases[n] || n }
end
def valid?
attribute_names.all? { |name| model.columns_hash[name] || model.reflect_on_aggregation(name.to_sym) }
end
def define
model.class_eval <<-CODE, __FILE__, __LINE__ + 1
def self.#{name}(#{signature})
#{body}
end
CODE
end
private
def body
"#{finder}(#{attributes_hash})"
end
# The parameters in the signature may have reserved Ruby words, in order
# to prevent errors, we start each param name with `_`.
def signature
attribute_names.map { |name| "_#{name}" }.join(", ")
end
# Given that the parameters starts with `_`, the finder needs to use the
# same parameter name.
def attributes_hash
"{" + attribute_names.map { |name| ":#{name} => _#{name}" }.join(",") + "}"
end
def finder
raise NotImplementedError
end
end
class FindBy < Method
Method.matchers << self
def self.prefix
"find_by"
end
def finder
"find_by"
end
end
class FindByBang < Method
Method.matchers << self
def self.prefix
"find_by"
end
def self.suffix
"!"
end
def finder
"find_by!"
end
end
end
end
|
