A consumer of my REST API says that on occasion I am returning a 400 Bad Request - The request sent by the client was syntactically incorrect. error.
My application (Python/Flask) logs don't seem to be capturing this, and neither do my webserver/Nginx logs.
Edit: I would like to try to cause a 400 bad request in Flask for debugging purposes. How can I do this?
Following James advice, I added something similar to the following:
@app.route('/badrequest400')
def bad_request():
return abort(400)
When I call this, flask returns the following HTML, which doesn't use the "The request sent by the client was syntactically incorrect" line:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<title>400 Bad Request</title>
<h1>Bad Request</h1>
<p>The browser (or proxy) sent a request that this server could not understand.</p>
(I'm not sure why it isn't including the <body> tags.
It appears to me that there are different variations of the 400 error message. For example, if I set a cookie to a value of length 50,000 (using Interceptor with Postman), I'll get the following error from Flask instead:
<html>
<head>
<title>Bad Request</title>
</head>
<body>
<h1>
<p>Bad Request</p>
</h1>
Error parsing headers: 'limit request headers fields size'
</body>
</html>
Is there a way to get Flask to through the different variations of 400 errors?
You can use abort to raise an HTTP error by status code.
from flask import abort
@app.route('/badrequest400')
def bad_request():
abort(400)
you can return the status code as a second parameter of the return, see example below
@app.route('/my400')
def my400():
code = 400
msg = 'my message'
return msg, code
You can also use abort with custom message error:
from flask import abort
abort(400, 'My custom message')
See https://flask-restplus.readthedocs.io/en/stable/errors.html
来源：https://stackoverflow.com/questions/32342528/how-to-intentionally-cause-a-400-bad-request-in-python-flask