""" useful context functions, see http://jinja.pocoo.org/docs/dev/api/#jinja2.contextfunction """ from typing import Any, Dict, cast import jinja2 from aiohttp import web from yarl import URL @jinja2.contextfunction def url_for(context: Dict[str, Any], __route_name: str, **parts: Any) -> URL: """Filter for generating urls. Usage: {{ url('the-view-name') }} might become "/path/to/view" or {{ url('item-details', id=123, query={'active': 'true'}) }} might become "/items/1?active=true". """ app = cast(web.Application, context["app"]) query = None if "query_" in parts: query = parts.pop("query_") for key in parts: val = parts[key] if isinstance(val, str): # if type is inherited from str expilict cast to str makes sense # if type is exactly str the operation is very fast val = str(val) elif type(val) is int: # int inherited classes like bool are forbidden val = str(val) else: raise TypeError( "argument value should be str or int, " "got {} -> [{}] {!r}".format(key, type(val), val) ) parts[key] = val url = app.router[__route_name].url_for(**parts) if query: url = url.with_query(query) return url @jinja2.contextfunction def static_url(context: Dict[str, Any], static_file_path: str) -> str: """Filter for generating urls for static files. NOTE: you'll need to set app['static_root_url'] to be used as the root for the urls returned. Usage: {{ static('styles.css') }} might become "/static/styles.css" or "http://mycdn.example.com/styles.css" """ app = context["app"] try: static_url = app["static_root_url"] except KeyError: raise RuntimeError( "app does not define a static root url " "'static_root_url', you need to set the url root " "with app['static_root_url'] = '<static root>'." ) from None return "{}/{}".format(static_url.rstrip("/"), static_file_path.lstrip("/")) GLOBAL_HELPERS = dict( url=url_for, static=static_url, )