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June 12, 2018 02:56
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# frozen_string_literal: true | |
module ActiveRecord | |
module DynamicMatchers #:nodoc: | |
private | |
def respond_to_missing?(name, _) | |
if self == Base | |
super | |
else | |
match = Method.match(self, name) | |
match && match.valid? || super | |
end | |
end | |
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 |
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