Add some documentation

3 files changed, 58 insertions, 2 deletions

diff --git a/lib/active_storage/attached/macros.rb b/lib/active_storage/attached/macros.rb
index 96493d1215..1e0f9a6b7e 100644
--- a/lib/active_storage/attached/macros.rb
+++ b/lib/active_storage/attached/macros.rb
@@ -1,7 +1,18 @@
 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.
+  #
+  # 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_get("@active_storage_attached_#{name}") ||
         instance_variable_set("@active_storage_attached_#{name}", ActiveStorage::Attached::One.new(name, self))
     end
 
@@ -10,9 +21,20 @@ module ActiveStorage::Attached::Macros
     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.
+  #
+  # 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_get("@active_storage_attached_#{name}") ||
         instance_variable_set("@active_storage_attached_#{name}", ActiveStorage::Attached::Many.new(name, self))
     end
 
diff --git a/lib/active_storage/attached/many.rb b/lib/active_storage/attached/many.rb
index f1535dfbc6..99d980196a 100644
--- a/lib/active_storage/attached/many.rb
+++ b/lib/active_storage/attached/many.rb
@@ -1,20 +1,36 @@
+# Representation of multiple attachments to a model.
 class ActiveStorage::Attached::Many < ActiveStorage::Attached
   delegate_missing_to :attachments
 
+  # Returns all the associated attachment records.
+  #
+  # You don't have to call this method to access the attachments' methods as
+  # they are all available at the model level.
   def attachments
     @attachments ||= ActiveStorage::Attachment.where(record_gid: record.to_gid.to_s, name: name)
   end
 
+  # Associates one or several attachments with the current record, saving
+  # them to the database.
   def attach(*attachables)
     @attachments = attachments | Array(attachables).flatten.collect do |attachable|
       ActiveStorage::Attachment.create!(record_gid: record.to_gid.to_s, name: name, blob: create_blob_from(attachable))
     end
   end
 
+  # Checks the presence of attachments.
+  #
+  #   class Gallery < ActiveRecord::Base
+  #     has_many_attached :photos
+  #   end
+  #
+  #   Gallery.new.photos.attached? # => false
   def attached?
     attachments.any?
   end
 
+  # Directly purges each associated attachment (i.e. destroys the blobs and
+  # attachments and deletes the files on the service).
   def purge
     if attached?
       attachments.each(&:purge)
@@ -22,6 +38,7 @@ class ActiveStorage::Attached::Many < ActiveStorage::Attached
     end
   end
 
+  # Purges each associated attachment through the queuing system.
   def purge_later
     if attached?
       attachments.each(&:purge_later)
diff --git a/lib/active_storage/attached/one.rb b/lib/active_storage/attached/one.rb
index d08d265992..80e4cb6234 100644
--- a/lib/active_storage/attached/one.rb
+++ b/lib/active_storage/attached/one.rb
@@ -1,18 +1,34 @@
+# Representation of a single attachment to a model.
 class ActiveStorage::Attached::One < ActiveStorage::Attached
   delegate_missing_to :attachment
 
+  # Returns the associated attachment record.
+  #
+  # You don't have to call this method to access the attachment's methods as
+  # they are all available at the model level.
   def attachment
     @attachment ||= ActiveStorage::Attachment.find_by(record_gid: record.to_gid.to_s, name: name)
   end
 
+  # Associates a given attachment with the current record, saving it to the
+  # database.
   def attach(attachable)
     @attachment = ActiveStorage::Attachment.create!(record_gid: record.to_gid.to_s, name: name, blob: create_blob_from(attachable))
   end
 
+  # Checks the presence of the attachment.
+  #
+  #   class User < ActiveRecord::Base
+  #     has_one_attached :avatar
+  #   end
+  #
+  #   User.new.avatar.attached? # => false
   def attached?
     attachment.present?
   end
 
+  # Directly purges the attachment (i.e. destroys the blob and
+  # attachment and deletes the file on the service).
   def purge
     if attached?
       attachment.purge
@@ -20,6 +36,7 @@ class ActiveStorage::Attached::One < ActiveStorage::Attached
     end
   end
 
+  # Purges the attachment through the queuing system.
   def purge_later
     if attached?
       attachment.purge_later