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rails--rails/lib/active_storage/attached/macros.rb
David Heinemeier Hansson 92536c08d5 Document the rest of lib
2017-07-24 15:36:33 -05:00

76 lines
3.5 KiB
Ruby

# Provides the class-level DSL for declaring that an Active Record model has attached blobs.
module ActiveStorage::Attached::Macros
# Specifies the relation between a single attachment and the model.
#
# class User < ActiveRecord::Base
# has_one_attached :avatar
# end
#
# There is no column defined on the model side, Active Storage takes
# care of the mapping between your records and the attachment.
#
# Under the covers, this relationship is implemented as a `has_one` association to a
# `ActiveStorage::Attachment` record and a `has_one-through` association to a
# `ActiveStorage::Blob` record. These associations are available as `avatar_attachment`
# and `avatar_blob`. But you shouldn't need to work with these associations directly in
# most circumstances.
#
# The system has been designed to having you go through the `ActiveStorage::Attached::One`
# proxy that provides the dynamic proxy to the associations and factory methods, like `#attach`.
#
# If the +:dependent+ option isn't set, the attachment will be purged
# (i.e. destroyed) whenever the record is destroyed.
def has_one_attached(name, dependent: :purge_later)
define_method(name) do
instance_variable_get("@active_storage_attached_#{name}") ||
instance_variable_set("@active_storage_attached_#{name}", ActiveStorage::Attached::One.new(name, self))
end
has_one :"#{name}_attachment", -> { where(name: name) }, class_name: "ActiveStorage::Attachment", as: :record
has_one :"#{name}_blob", through: :"#{name}_attachment", class_name: "ActiveStorage::Blob", source: :blob
if dependent == :purge_later
before_destroy { public_send(name).purge_later }
end
end
# Specifies the relation between multiple attachments and the model.
#
# class Gallery < ActiveRecord::Base
# has_many_attached :photos
# end
#
# There are no columns defined on the model side, Active Storage takes
# care of the mapping between your records and the attachments.
#
# To avoid N+1 queries, you can include the attached blobs in your query like so:
#
# Gallery.where(user: Current.user).with_attached_photos
#
# Under the covers, this relationship is implemented as a `has_many` association to a
# `ActiveStorage::Attachment` record and a `has_many-through` association to a
# `ActiveStorage::Blob` record. These associations are available as `photos_attachments`
# and `photos_blobs`. But you shouldn't need to work with these associations directly in
# most circumstances.
#
# The system has been designed to having you go through the `ActiveStorage::Attached::Many`
# proxy that provides the dynamic proxy to the associations and factory methods, like `#attach`.
#
# If the +:dependent+ option isn't set, all the attachments will be purged
# (i.e. destroyed) whenever the record is destroyed.
def has_many_attached(name, dependent: :purge_later)
define_method(name) do
instance_variable_get("@active_storage_attached_#{name}") ||
instance_variable_set("@active_storage_attached_#{name}", ActiveStorage::Attached::Many.new(name, self))
end
has_many :"#{name}_attachments", -> { where(name: name) }, as: :record, class_name: "ActiveStorage::Attachment"
has_many :"#{name}_blobs", through: :"#{name}_attachments", class_name: "ActiveStorage::Blob", source: :blob
scope :"with_attached_#{name}", -> { includes("#{name}_attachments": :blob) }
if dependent == :purge_later
before_destroy { public_send(name).purge_later }
end
end
end