Implement canned queries against new query JSON work

[simonw]

• Plan for getting the new JSON format query views working #2109

[simonw]

This is also where I'll bring back writable canned queries:

datasette/datasette/views/database.py

Lines 281 to 334 in 18dd88e

	# Execute query - as write or as read
	if write:
	if request.method == "POST":
	# If database is immutable, return an error
	if not db.is_mutable:
	raise Forbidden("Database is immutable")
	body = await request.post_body()
	body = body.decode("utf-8").strip()
	if body.startswith("{") and body.endswith("}"):
	params = json.loads(body)
	# But we want key=value strings
	for key, value in params.items():
	params[key] = str(value)
	else:
	params = dict(parse_qsl(body, keep_blank_values=True))
	# Should we return JSON?
	should_return_json = (
	request.headers.get("accept") == "application/json"
	or request.args.get("_json")
	or params.get("_json")
	)
	if canned_query:
	params_for_query = MagicParameters(params, request, self.ds)
	else:
	params_for_query = params
	ok = None
	try:
	cursor = await self.ds.databases[database].execute_write(
	sql, params_for_query
	)
	message = metadata.get(
	"on_success_message"
	) or "Query executed, {} row{} affected".format(
	cursor.rowcount, "" if cursor.rowcount == 1 else "s"
	)
	message_type = self.ds.INFO
	redirect_url = metadata.get("on_success_redirect")
	ok = True
	except Exception as e:
	message = metadata.get("on_error_message") or str(e)
	message_type = self.ds.ERROR
	redirect_url = metadata.get("on_error_redirect")
	ok = False
	if should_return_json:
	return Response.json(
	{
	"ok": ok,
	"message": message,
	"redirect": redirect_url,
	}
	)
	else:
	self.ds.add_message(request, message, message_type)
	return self.redirect(request, redirect_url or request.path)

[simonw]

The tests for this are still passing:

pytest tests/test_canned_queries.py

Because I left in the old code:

datasette/datasette/views/table.py

Lines 752 to 767 in cd57b0f

	async def table_view_traced(datasette, request):
	from datasette.app import TableNotFound
	try:
	resolved = await datasette.resolve_table(request)
	except TableNotFound as not_found:
	# Was this actually a canned query?
	canned_query = await datasette.get_canned_query(
	not_found.database_name, not_found.table, request.actor
	)
	# If this is a canned query, not a table, then dispatch to QueryView instead
	if canned_query:
	if request.method == "POST":
	return await CannedQueryView(datasette).post(request)
	else:
	return await CannedQueryView(datasette).get(request)

datasette/datasette/views/table.py

Lines 701 to 727 in cd57b0f

	class CannedQueryView(DataView):
	def __init__(self, datasette):
	self.ds = datasette
	async def post(self, request):
	from datasette.app import TableNotFound
	try:
	await self.ds.resolve_table(request)
	except TableNotFound as e:
	# Was this actually a canned query?
	canned_query = await self.ds.get_canned_query(
	e.database_name, e.table, request.actor
	)
	if canned_query:
	# Handle POST to a canned query
	return await QueryView(self.ds).data(
	request,
	canned_query["sql"],
	metadata=canned_query,
	editable=False,
	canned_query=e.table,
	named_parameters=canned_query.get("params"),
	write=bool(canned_query.get("write")),
	)
	return Response.text("Method not allowed", status=405)

[simonw]

I decided to figure out where the _size= parameter here comes from:

datasette/datasette/views/database.py

Lines 576 to 588 in cd57b0f

	class QueryView(DataView):
	async def data(
	self,
	request,
	sql,
	editable=True,
	canned_query=None,
	metadata=None,
	_size=None,
	named_parameters=None,
	write=False,
	default_labels=None,
	):

It took some spelunking, but it looks like I added that five years ago as part of CSV streaming in fc3660c

It's there purely to allow CSV streaming to set _size="max".

And since CSV streaming is still just a table thing, not a query thing, I can drop it.