Let register_routes() over-ride default routes within Datasette

[simonw]

See #878 (comment)_ - right now register_routes() can't replace default Datasette routes.

It would be neat if plugins could do this - especially if there was a neat documented way for them to then re-dispatch to the original route code after making some kind of modification.

[simonw]

I made a mistake: I just wrote a test that proves that plugins CAN over-ride default routes, plus if you look at the code here the plugins get to register themselves first:

datasette/datasette/app.py

Lines 965 to 981 in 0156c6b

	def app(self):
	"""Returns an ASGI app function that serves the whole of Datasette"""
	routes = []
	for routes_to_add in pm.hook.register_routes(datasette=self):
	for regex, view_fn in routes_to_add:
	routes.append((regex, wrap_view(view_fn, self)))
	def add_route(view, regex):
	routes.append((regex, view))
	# Generate a regex snippet to match all registered renderer file extensions
	renderer_regex = "|".join(r"\." + key for key in self.renderers.keys())
	add_route(IndexView.as_view(self), r"/(?P<as_format>(\.jsono?)?$)")
	# TODO: /favicon.ico and /-/static/ deserve far-future cache expires
	add_route(favicon, "/favicon.ico")

[simonw]

Confirmed - my test plugin is indeed correctly over-riding the table page.