Set an url prefix if Django is not mounted under / in production

[Wissperwind]

Hi,

The plugin identifies all urls correctly from djangos point of view.
But in production django has to be mounted in to a webserver. And under / is usually the folder for static files for the website.
So I mounted django under /backend. So an endpoint that is /getInfo in django is now /backend/getInfo in reality.

Is there an option to tell this to drf spectacular?
If not I would like to request this feature.
Thanks!

[tfranzel]

Hi,

since Django does not know about this, you need to set SERVERS in the spectacular settings.

'SERVERS': [{'url': 'https://example.com/backend'}]

[Wissperwind]

Ok, thanks for the anwser, I tried:
I added it to settings.py in the spectacular settings, where I also set title and description and some more.
Unfortunately it doesn't work.
It now diesplays "Could not render n, see the console." under the servers section on the swagger page.
But in the console I cannot finde a usefull message to that problem.
It shows many times "unable to guess serializer". But nothing about the server error.

[ngnpope]

I achieved this automatically by adding a post-processing hook:

from urllib.parse import urljoin

def set_request_server(result, generator, request, public):
    if request:
        url = urljoin(request.path, ".").rstrip("/")
        url = request.build_absolute_uri(url)
        result.setdefault("servers", []).append({"url": url})
    return result

This example works where my schema is hosted at, e.g. https://api.example.com/path/to/schema.json and I want the base to be https://api.example.com/path/to/. You can tweak this to suit your needs. Not sure whether you'd like to adopt something like this in the FAQ?

[Wissperwind]

I dont understand what the preprocessing hook does yet.
I don't need to change anything of the behaviour of django. It ansers the requests well.
Only at the swagger page it shall add a /backend before all requests when running in production.

[tfranzel]

@Wissperwind, sry I made a mistake there. its a list and not just one dict

    'SERVERS': [
        {
            "url": "https://gigantic-server.com/v1",
            "description": "Production server"
        },
        {
            "url": "https://development.gigantic-server.com/v1",
            "description": "Development server"
        }
    ],

this will not add the backend prefix on the operation entries, but it is used when you use "Try it out" on Swagger UI. The curl command will have the correct full url

[Wissperwind]

Ah, ok. Now something works.
I can add:

    'SERVERS': [
        {
            "url": "/backend",
        }
    ],

And it adds the prefix to each call and uses still automatic the current host.
The server url can be specified from the customer and I don't know it here.

But there is still a problem. The prefix is not displayed to each URL. So if I show the swagger page to the developers, they will see /api/# and think, OK, let's call localhost:8000/api/#. But that will not work. They have to call localhost:8000/backend/api/#. Sure I can to explain it to them. But some will forget it sometimes. How about a real prefix setting?

[tfranzel]

added new setting SCHEMA_PATH_PREFIX_INSERT to model theses prefixes.

of course this is hard-coded in comparison to @ngnpope's hook but i suppose this covers the most typical use-cases

[Wissperwind]

That works perfectly!
Exactly what I needed. Thanks.

[Wissperwind]

Ok, so can this issue be closed now?
Is this already in a public release?

[tfranzel]

yes its released in 0.20.2. it can be closed.

[john-carroll-sw]

I achieved this automatically by adding a post-processing hook:

from urllib.parse import urljoin

def set_request_server(result, generator, request, public):
    if request:
        url = urljoin(request.path, ".").rstrip("/")
        url = request.build_absolute_uri(url)
        result.setdefault("servers", []).append({"url": url})
    return result

This example works where my schema is hosted at, e.g. https://api.example.com/path/to/schema.json and I want the base to be https://api.example.com/path/to/. You can tweak this to suit your needs. Not sure whether you'd like to adopt something like this in the FAQ?

Hi Nick, where would one place this post-processing hook?

[tfranzel]

it does not matter where. you just need to set in the import path in the spectacular setting POSTPROCESSING_HOOKS. make sure you don't forget to add the enum postprocessing hook back in to the list.

see doc for more details:

https://drf-spectacular.readthedocs.io/en/latest/customization.html#step-6-postprocessing-hooks