Extractor configurability #404
Description
Is there an existing issue for this?
- I have searched the existing issues
Is your feature request related to a problem? Please describe
Association extractor is useful to modify to e.g. add a circuit-breaker, implement caching and for a few other things. Right now it's somewhat complicated to override/modify.
Describe the feature you'd like to see implemented
Right now, there are two types of extractors: AssociationExtractor and AutoExtractor (along with some sub-extractors).
Their roles are somewhat intertwined (AssociationExtractor calls the AutoExtractor, for example), and only one of them can be modified globally.
I'd propose a stricter separation, splitting it up into (probably) three extractors:
- FieldExtractor
- AssociationExtractor
- ValueExtractor (or DataExtractor)
The default ValueExtractor would encapsulate the logic currently existing in AutoExtractor, and I'd move the logic of deferring to block to field/association extractors. ValueExtractor could also be named something like DataExtractor instead.
Example
This is a rough sketch, in reality it would probably be slightly different.
class ValueExtractor < Extractor
def extract(field_name, object, local_options, options = {})
if object.is_a?(Hash)
value = extract_hash(field_name, object, local_options, options)
else
value = extract_send(field_name, object, local_options, options)
end
end
private
def extract_hash(field_name, object, _local_options, _options = {})
object[field_name]
end
def extract_send(field_name, object, _local_options, _options = {})
object.public_send(field_name)
end
end
class FieldExtractor < Extractor
include EmptyTypes
def initialize
@extractor = Blueprinter.configuration.field_extractor_default.new # `ValueExtractor.new` by default
end
def extract(field_name, object, local_options, options = {})
if options[:block]
value = options[:block].call(object, local_options)
else
value = @value_extractor.extract(field_name, object, local_options, options)
end
value = @datetime_formatter.format(value, options)
use_default_value?(value, options[:default_if]) ? default_value(options) : value
end
private
def default_value(field_options)
field_options.key?(:default) ? field_options.fetch(:default) : Blueprinter.configuration.field_default
end
end
class AssociationExtractor < Extractor
include EmptyTypes
def initialize
@extractor = Blueprinter.configuration.field_extractor_default.new # `ValueExtractor.new` by default
end
def extract(association_name, object, local_options, options = {})
options_without_default = options.except(:default, :default_if)
# Merge in assocation options hash
local_options = local_options.merge(options[:options]) if options[:options].is_a?(Hash)
if options[:block]
value = options[:block].call(object, local_options)
else
value = @value_extractor.extract(association_name, object, local_options, options)
end
return default_value(options) if use_default_value?(value, options[:default_if])
view = options[:view] || :default
blueprint = association_blueprint(options[:blueprint], value)
blueprint.prepare(value, view_name: view, local_options: local_options)
end
private
def default_value(association_options)
return association_options.fetch(:default) if association_options.key?(:default)
Blueprinter.configuration.association_default
end
def association_blueprint(blueprint, value)
blueprint.is_a?(Proc) ? blueprint.call(value) : blueprint
end
endDescribe alternatives you've considered
No response
Additional context
No response