An example self-rendering model component.

self-rendering-models.py

from marrow.mongo import utcnow
from marrow.mongo.trait import Identified
from marrow.mongo.field import Date, Markdown, Reference

from ..asset import Depend


__all__ = ('Note', )


class Note(Identified):
	"""An embedded document representing a textual reply, comment, or note."""
	
	# Fields
	
	id = Identified.id.adapt(positional=False, write=False)  # Exclude from constructor and prevent writes.
	
	author = Reference('Account', cache={'name'}, required=True)  # Keep a copy of the user's name to save a lookup.
	message = Markdown(required=True, repr=False)
	
	created = Date(default=utcnow, assign=True)  # Avoid ID generation time to permit aggregation and querying.
	modified = Date(default=None)
	
	# Self-Rendering Protocols
	
	@Depend.declare
	def __depends__(Note, only):
		"""Declare bundle, themeing, and interaction points for this widget."""
		
		if Depend.STYLE in only:  # CSS selectors that a theme may wish to customize.
			yield Depend.STYLE, 'figure.note'
		
		if Depend.EVENT in only:  # Client- and server-side events that may fire.
			yield Depend.EVENT, 'com.cegid.Note:added'
			yield Depend.EVENT, 'com.cegid.Note:updated'
			yield Depend.EVENT, 'com.cegid.Note:removed'
	
	def __html__(self):
		"""Return a microdata-compliant HTML representation for this object."""
		
		return f'''<figure class=note>
	<blockquote>{self.message.__html__()}</blockquote>
	<figcaption>by {self.author.name} on <time datetime={self.created.isoformat('T', 'seconds')}>{self.created.strftime('%Y/%m/%d').replace('/0', '/')} at {self.created.strftime('%H:%M')}</time></figcaption>
</figure>'''