"""
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,
)