[Messages] Pydantic schema for message validation

[odesenfans]

Added new Pydantic models/schemas to validate Aleph messages
coming from the network. These models are similar to the ones
implemented in aleph-message, but focus on validating messages
before processing them.

This validation replaces the validation in check_message
and will later be used to use objects as early as possible
in the processing of messages.

Added tests for the major types of messages.

Breaking changes (to validate):

• the item_type field is now mandatory for all message types
• the address and time fields are now mandatory for the content of all messages.
• PROGRAM: allow_amend and code.comment are now mandatory.

[odesenfans]

Depends on #271.

[hoh]

Not a fan of _ =

[odesenfans]

Me neither, but it's to show that I'm not ignoring the return value until this line goes away in #277.

[hoh]

Does this need to be a root validator instead of a simple validator ?

[odesenfans]

Yes, if only because we're accessing other fields. The main problem is that check_item_hash uses item_type and check_item_type uses item_hash, so at least one of the functions has to be a root validator.

[hoh]

This code is identical to the one in aleph-message. Can we do something like this, or do the decorators get in the way ?

Suggested change

	@validator("item_hash")
	def check_item_hash(cls, v, values):
	"""
	For inline item types, check that the item hash is equal to
	the hash of the item content.
	"""
	item_type = values["item_type"]
	if item_type == ItemType.inline:
	item_content: str = values["item_content"]
	computed_hash: str = sha256(item_content.encode()).hexdigest()
	if v != computed_hash:
	raise ValueError(
	"'item_hash' do not match 'sha256(item_content)'"
	f", expecting {computed_hash}"
	)
	elif item_type == ItemType.ipfs:
	# TODO: CHeck that the hash looks like an IPFS multihash
	pass
	else:
	assert item_type == ItemType.storage
	return v
	check_item_hash = aleph_message.models.BaseMessage.check_item_hash

Suggested change

	@validator("item_hash")
	def check_item_hash(cls, v, values):
	"""
	For inline item types, check that the item hash is equal to
	the hash of the item content.
	"""
	item_type = values["item_type"]
	if item_type == ItemType.inline:
	item_content: str = values["item_content"]
	computed_hash: str = sha256(item_content.encode()).hexdigest()
	if v != computed_hash:
	raise ValueError(
	"'item_hash' do not match 'sha256(item_content)'"
	f", expecting {computed_hash}"
	)
	elif item_type == ItemType.ipfs:
	# TODO: CHeck that the hash looks like an IPFS multihash
	pass
	else:
	assert item_type == ItemType.storage
	return v
	@validator("item_hash")
	def check_item_hash(cls, v, values):
	return aleph_message.models.BaseMessage.check_item_hash(v, values)

[odesenfans]

Just tried it, the validator does not get in the way but I removed the hash_type member of the message model, if only because we will probably never use it (better to use multihash/multicodec instead). If that's okay for you, I think I'll leave it like that for the moment, and we'll do a large update of aleph_message once we're fixed on the models.

I basically want to have a class tree like this:

• PendingMessage: base class, = the data sent by aleph-client or similar
• DbMessage: inherits PendingMessage (or a common base class), = the schema of the data stored in MongoDB.
• ApiMessage: inherits DbMessage (or a common base class), = the schema of the API response. Similar to the current aleph_message Message.