67 lines
1.9 KiB
Ruby
67 lines
1.9 KiB
Ruby
|
# references:
|
||
|
|
# https://github.com/Shopify/graphql-batch/blob/master/examples/association_loader.rb
|
||
|
|
# https://gist.github.com/palkan/03eb5306a1a3e8addbe8df97a298a466
|
||
|
|
# https://evilmartians.com/chronicles/active-storage-meets-graphql-pt-2-exposing-attachment-urls
|
||
|
|
|
||
|
|
module Loaders
|
||
|
|
class Association < GraphQL::Batch::Loader
|
||
|
|
def self.validate(model, association_name)
|
||
|
|
new(model, association_name)
|
||
|
|
nil
|
||
|
|
end
|
||
|
|
|
||
|
|
def initialize(model, association_schema)
|
||
|
|
@model = model
|
||
|
|
@association_schema = association_schema
|
||
|
|
@association_name = extract_association_id(association_schema)
|
||
|
|
validate
|
||
|
|
end
|
||
|
|
|
||
|
|
def load(record)
|
||
|
|
raise TypeError, "#{@model} loader can't load association for #{record.class}" unless record.is_a?(@model)
|
||
|
|
return Promise.resolve(read_association(record)) if association_loaded?(record)
|
||
|
|
super
|
||
|
|
end
|
||
|
|
|
||
|
|
# We want to load the associations on all records, even if they have the same id
|
||
|
|
def cache_key(record)
|
||
|
|
record.object_id
|
||
|
|
end
|
||
|
|
|
||
|
|
def perform(records)
|
||
|
|
preload_association(records.uniq)
|
||
|
|
records.each { |record| fulfill(record, read_association(record)) }
|
||
|
|
end
|
||
|
|
|
||
|
|
private
|
||
|
|
|
||
|
|
def validate
|
||
|
|
unless @model.reflect_on_association(@association_name)
|
||
|
|
raise ArgumentError, "No association #{@association_name} on #{@model}"
|
||
|
|
end
|
||
|
|
end
|
||
|
|
|
||
|
|
def preload_association(records)
|
||
|
|
::ActiveRecord::Associations::Preloader.new.preload(records, @association_schema)
|
||
|
|
end
|
||
|
|
|
||
|
|
def read_association(record)
|
||
|
|
record.public_send(@association_name)
|
||
|
|
end
|
||
|
|
|
||
|
|
def association_loaded?(record)
|
||
|
|
record.association(@association_name).loaded?
|
||
|
|
end
|
||
|
|
|
||
|
|
def extract_association_id(id_or_hash)
|
||
|
|
return id_or_hash unless id_or_hash.is_a?(Hash)
|
||
|
|
|
||
|
|
if id_or_hash.keys.size != 1
|
||
|
|
raise ArgumentError, "You can only preload exactly one association! You passed: #{id_or_hash}"
|
||
|
|
end
|
||
|
|
|
||
|
|
id_or_hash.keys.first
|
||
|
|
end
|
||
|
|
end
|
||
|
|
end
|