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# frozen-string-literal: true
module Sequel
module Plugins
# The association_lazy_eager_option plugin supports passing
# an +:eager+ option to an association method. If the related
# association is already cached, the cached version will be
# returned. If the association is not already cached, it will
# be loaded, and the value of the +:eager+ option will be used
# to perform an eager load of the given associations.
# the plural versions.
#
# With Sequel's default behavior, you can already perform an
# eager load when lazy loading using a block:
#
# obj.association{|ds| ds.eager(:nested_association)}
#
# However, this will ignore any cached version. In more
# complex software, the association may already be cached
# and have the nested association cached inside of it, and
# using this callback approach then requires 2 unnecessary
# queries. This plugin will not perform any queries if the
# association is already cached, preventing duplicate work.
# However, you should make sure that an already loaded
# association has the nested association already eagerly
# loaded.
#
# Usage:
#
# # Make all model subclasses support the :eager association
# # method option (called before loading subclasses)
# Sequel::Model.plugin :association_lazy_eager_option
#
# # Make the Album class support the :eager association
# # method option
# Album.plugin :association_lazy_eager_option
module AssociationLazyEagerOption
module InstanceMethods
private
# Return a dataset for the association after applying any dynamic callback.
def _associated_dataset(opts, dynamic_opts)
ds = super
if eager = dynamic_opts[:eager]
ds = ds.eager(eager)
end
ds
end
# A placeholder literalizer that can be used to load the association, or nil to not use one.
def _associated_object_loader(opts, dynamic_opts)
return if dynamic_opts[:eager]
super
end
# Whether to use a simple primary key lookup on the associated class when loading.
def load_with_primary_key_lookup?(opts, dynamic_opts)
return false if dynamic_opts[:eager]
super
end
end
end
end
end
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