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Out of the box Starlette does not support url_for with query params. When trying to use url_for with query params it throws the following error.
starlette.routing.NoMatchFound: No route exists for name "infinite" and params "page"
In my searching for this I found starlette issue #560 quite helpful, but not complete, as it did not work for me.
import jinja2
if hasattr(jinja2, "pass_context"):
pass_context = jinja2.pass_context
else:
pass_context = jinja2.contextfunction
@pass_context
def url_for_query(context: dict, name: str, **params: dict) -> str:
request = context["request"]
url = str(request.url_for(name))
if params == {}:
return url
from urllib.parse import parse_qs, urlencode, urlparse, urlunparse
# Parse the URL
parsed_url = urlparse(url)
# Parse the query parameters
query_params = parse_qs(parsed_url.query)
# Update the query parameters with the new ones
query_params.update(params)
# Rebuild the query string
updated_query_string = urlencode(query_params, doseq=True)
# Rebuild the URL with the updated query string
updated_url = urlunparse(
(
parsed_url.scheme,
parsed_url.netloc,
parsed_url.path,
parsed_url.params,
updated_query_string,
parsed_url.fragment,
)
)
if os.environ.get("ENV") in ["dev", "qa", "prod"]:
updated_url = updated_url.replace("http", "https", 1)
return updated_url
def get_templates():
templates = Jinja2Templates(directory="templates")
templates.env.globals["url_for"] = url_for_query
return templates
!!! Note "https"
If you want url_for to work in production you need some way to convert http
to https. Here is how I make it work, for local development I export ENV=local then for each environment that I am running on a server I include
it in the list and update ENV appropriately.
``` python
if os.environ.get("ENV") in ["dev", "qa", "prod"]:
updated_url = updated_url.replace("http", "https", 1)
```
The route might look something like this.
@infinite_router.get("/")
async def home(request: Request, page: int = 1, n: int = 10):
...
To access the home route using url_for in a jinja template you can use the
following, once you have applied the url_for_query function as your default
url_for
<a href="{{ url_for('home', page=1) }}">Home</a>