[BUG] Exception Handlers Return 200 Status Code Instead of Original Error Code

[tom-pollak]

@jph00

When using custom exception handlers, the response status code defaults to 200 instead of preserving the original error code. This occurs unless explicitly returning a HTMLResponse with the correct status code.

This can be worked around by explicitly returning a Response with the correct status code, but maybe documented?

For example:

fasthtml/examples/adv_app.py

Line 65 in 0d05029

def _not_found(req, exc): return Titled('Oh no!', Div('We could not find that page :('))

Related: #460

Minimal example:

# %%
import requests
from fasthtml.common import *
from fasthtml.jupyter import JupyUvi

# problem
def _not_found(req, exc):
    print("(404 hit)")
    return Titled("404", "Page not found")

# current workaround -- to_xml required to convert to html string
def _unauthorized(req, exc):
    print("(401 hit)")
    return HTMLResponse(to_xml(Titled("401", "Unauthorized")), status_code=401)

app, rt = fast_app(exception_handlers={404: _not_found, 401: _unauthorized})

@rt()
def admin(req):
    print("(admin hit)")
    raise HTTPException(status_code=401, detail="Unauthorized")

@rt
def bad_request(req):
    print("(bad request hit)")
    raise HTTPException(status_code=400, detail="Bad Request")

server = JupyUvi(app)

# %%

# shows the error, by default the exception handler returns a 200 rather than 404
res_404 = requests.get("http://localhost:8000/not_found")
print(f"Response 404 handler (Titled): status_code={res_404.status_code}\n")

# a workaround for this, return a HTMLResponse directly
res_401 = requests.get("http://localhost:8000/admin")
print(f"Response 401 handler (manually set status code): status_code={res_401.status_code}\n")

# no exception handler for 400
res_400 = requests.get("http://localhost:8000/bad_request")
print(f"Response 400 (No handler): status_code={res_400.status_code}\n")

Output:

(404 hit)
Response 404 handler (Titled): status_code=200

(admin hit)
(401 hit)
Response 401 handler (Manually set status code): status_code=401

(bad request hit)
Response 400 (No handler): status_code=400

Environment Information

• fastlite: 0.1.1
• fastcore: 1.7.27
• fasthtml: 0.12.0

Confirmation
Please confirm the following:

• I have read the FAQ (https://docs.fastht.ml/explains/faq.html)
• I have provided a minimal reproducible example
• I have included the versions of fastlite, fastcore, and fasthtml
• I understand that this is a volunteer open source project with no commercial support.

[tom-pollak]

PR in #636