# Base serializable entity that can go into a JsonRepository
#
# Provide boiler plate implementation of all object serializable to json.
#
# `id` is used as a primary key for `find_by_id`.
#
# Subclassing RepoObject makes it easy to create a serializable class:
# ~~~
# import popcorn::pop_repos
#
# class Album
#	super RepoObject
#	serialize
#
#	var title: String
#	var price: Float
# end
# ~~~
#
# Do not forget the `serialize` annotation else the fields will not be serialized.
#
# It is also possible to redefine the `id` primary key to use your own:
# ~~~
# import popcorn::pop_repos
#
# class Order
#	super RepoObject
#	serialize
#
#	redef var id = "order-{get_time}"
#
#	# ...
#
# end
# ~~~
abstract class RepoObject
	serialize

	# `self` unique id.
	#
	# This attribute is serialized under the key `_id` to be used
	# as primary key by MongoDb
	var id: String = (new MongoObjectId).id is writable, serialize_as "_id"

	# Base object comparison on ID
	#
	# Because multiple deserialization can exists of the same instance,
	# we use the ID to determine if two object are the same.
	redef fun ==(o) do return o isa SELF and id == o.id

	redef fun hash do return id.hash
	redef fun to_s do return id
end