I can’t figure out if it’s possible to pass query parameters from a static html page to a view for processing. I have now implemented the functionality I need using path parameters. I want to do the same, but with query parameters
main.py
from helpers.utils import CustomURLProcessor app = FastAPI() app.mount("/static", StaticFiles(directory="static"), name="static") templates = Jinja2Templates(directory="templates") templates.env.globals['CustomURLProcessor'] = CustomURLProcessor
events.py
router = APIRouter() templates = Jinja2Templates(directory="templates") @router.post('/invite/{event_invite}/sender/{sender}') async def decline_event_invite( request: Request, event_invite: int, sender: int, ): #logic
routes.py
api_router.include_router(events.router, prefix="/event")
html
{{ url_for('decline_event_invite', event_invite=invite.id, sender=invite.sender) }}
It’s works with "POST /event/invite/15/sender/3 HTTP/1.1"
as a sample
Try with query params
@router.post('/invite') async def decline_event_invite( request: Request, event_invite: Optional[str] = None, sender: Optional[str] = None, ): # logic
And get
raise NoMatchFound() starlette.routing.NoMatchFound
html template without any change
Can I pass query parameters from the template to the fastapi logic to processing this url /event/?event_invite=15&sender=3
?
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Answer
This is Starlette’s issue (i.e., url_for()
receives path
parameters, not query
parameters). What you could do is to create a custom URL processor (as shown below) and use it to pass path
and/or query
parameters as well.
import urllib class CustomURLProcessor: def __init__(self): self.path = "" self.request = None def url_for(self, request: Request, name: str, **params: str): self.path = request.url_for(name, **params) self.request = request return self def include_query_params(self, **params: str): parsed = list(urllib.parse.urlparse(self.path)) parsed[4] = urllib.parse.urlencode(params) return urllib.parse.urlunparse(parsed)
Remember to add the CustomURLProcessor
class to the templates’ global environment:
templates.env.globals['CustomURLProcessor'] = CustomURLProcessor
Then, use in Jinja template, as below:
{{ CustomURLProcessor().url_for(request, 'decline_event_invite').include_query_params(event_invite=invite.id, sender=invite.sender) }}
Please have a look at this answer for a complete working example. Also, this feature might be introduced into the next version of Starlette #1385. Thus, you may want to keep an eye on it.
More options on how to make a class accessible from Jinja templates
Alternative options to make CustomURLProcessor
class accessible from Jinja templates, in case templates.env.globals['CustomURLProcessor'] = CustomURLProcessor
didn’t work for you, throwing the following error: jinja2.exceptions.UndefinedError: 'CustomURLProcessor' is undefined
.
Option 1
templates.env.globals.update(CustomURLProcessor=CustomURLProcessor)
Option 2
import helpers.utils templates.env.globals['CustomURLProcessor'] = helpers.utils.CustomURLProcessor # or, equivalently templates.env.globals.update(CustomURLProcessor=helpers.utils.CustomURLProcessor)
You could even add the whole module, and use in Jinja template like this helpers.CustomURLProcessor().url_for(request...
.
import helpers.utils templates.env.globals['helpers'] = helpers.utils
Option 3
The last option would be to pass it as part of your TemplateResponse
.
return templates.TemplateResponse("index.html", {"request": request, "CustomURLProcessor": CustomURLProcessor})
If none of the above worked, perhaps other options described here might help, or the problem likely lies elsewhere.
Update – About including query params
Regarding sending query parameters from a Jinja template, you can now use Starlette’s starlette.datastructures.URL
, which provides an include_query_params
method.
To use, import the URL
class and make it accessible from Jinja2 templates:
from starlette.datastructures import URL templates = Jinja2Templates(directory="templates") templates.env.globals['URL'] = URL
Then, use in Jinja template as shown below:
{{ URL(url_for('decline_event_invite')).include_query_params(event_invite=invite.id, sender=invite.sender) }}