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module ActiveRecord
module AttributeDecorators # :nodoc:
extend ActiveSupport::Concern
included do
class_attribute :attribute_type_decorations, instance_accessor: false # :internal:
self.attribute_type_decorations = TypeDecorator.new
end
module ClassMethods
def decorate_attribute_type(column_name, decorator_name, &block)
matcher = ->(name, _) { name == column_name.to_s }
key = "_#{column_name}_#{decorator_name}"
decorate_matching_attribute_types(matcher, key, &block)
end
def decorate_matching_attribute_types(matcher, decorator_name, &block)
clear_caches_calculated_from_columns
decorator_name = decorator_name.to_s
# Create new hashes so we don't modify parent classes
self.attribute_type_decorations = attribute_type_decorations.merge(decorator_name => [matcher, block])
end
private
def add_user_provided_columns(*)
super.map do |column|
decorated_type = attribute_type_decorations.apply(self, column.name, column.cast_type)
column.with_type(decorated_type)
end
end
end
class TypeDecorator
delegate :clear, to: :@decorations
def initialize(decorations = {})
@decorations = decorations
end
def merge(*args)
TypeDecorator.new(@decorations.merge(*args))
end
def apply(context, name, type)
decorations = decorators_for(context, name, type)
decorations.inject(type) do |new_type, block|
block.call(new_type)
end
end
private
def decorators_for(context, name, type)
matching(context, name, type).map(&:last)
end
def matching(context, name, type)
@decorations.values.select do |(matcher, _)|
context.instance_exec(name, type, &matcher)
end
end
end
end
end
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