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TIL: Getting HTTP Status Codes from Flask errorhandler

Published 2020-07-24 — RSS

When you're using Flasks errorhandler decorator for a specific HTTP status code it's clear what HTTP status code the response will be:

from flask import Flask

app = Flask(__name__)

@app.errorhandler(404)
def on_not_found(error):
    return "This is a 404 for sure!", 404

However I didn't know how to write an error handler that handles all HTTP status calls, abort(XYZ) calls, and just general exceptions being raised from the stack. This is what I ended up with:

from flask import Flask

app = Flask(__name__)

@app.errorhandler(Exception)
def on_error(error):
    return "This is an error!", ... # <- What do I put here?

but I wasn't sure how to get the status code from the HTTPException that Flask was going to raise (another thing to note is that HTTPException is from werkzeug, not from Flask). I tried "status_code" and "status", to no avail and then ran dir() on the error which revealed "code" as the property to use. This was my final function without a ton of guards since it's for a quick project:

from flask import Flask

app = Flask(__name__)

@app.errorhandler(Exception)
def on_error(error):
    # Errors raised from places besides abort()
    # or routing failures will have a status code
    # of 500 for internal error.
    status_code = getattr(error, "code", 500)
    return f"HTTP Error {status_code}", status_code