app.py

# In your app, make sure to tell the serializer that your model objects are serializable...
# Helps if your model classes share a common base class you can register.

from collections import Mapping


app = Application(..., extensions=[
	...
	SerializationExtension(types=(list, Mapping, YourModel)),
	...
])

model.py

# Your data model.  Of some kind.

# Updated to use templates and stuff.

from marrow.package.loader import load  # one way...

from .template.artist import render_html  # another...


class Artist(Document):
	name = String()
	bio = String()
	...
	
	def __json__(self):
		return "{json...}"
	
	#def __html__(self):
	#	return render_html()
	# ^ lame
	
	__html__ = render_html  # baws
	
	__xml__ = load('web.app.MYAPP.template.artist:render_xml')  # clean

render.py

def _render(kind):
	attr = '__{}__'.format(kind)
	
	def render(thing):
		return getattr(thing, attr)()

html = _render('html')
xml = _render('xml')

setup.py

# Add this stuff to your own, and make sure to run "pip install -e ." or "setup.py develop" again.

...

setup(
	...,
	
	entry_points = {
			'web.serialize': [
					'html = web.app.APPNAME.render:html',
					'text/html = web.app.APPNAME.render:html',
					'xml = web.app.APPNAME.render:html',
					'application/xml = web.app.APPNAME.render:html',
				]
		},
	
	...
)