How do I raise an http error/exception from a python CGI script?

Question

Is all that is necessary is to print the appropriate header:

print '''Status: 501 Not Implemented
Content-type: text/html

'''

That doesn't seem to work right.

I have a very basic setup, namely IIS7 routing *.py CGI scripts to python25.exe for execution. I am not using any WSGI or FastCGI. Using the "normal" CGI modules: cgitb and cgi

I think it might help to provide your setup. What web server are you running and what modules are you using? Are you using FastCGI? What library is providing the access to CGI environment variables and such? Doesn't it also provide methods for handling HTTP transactions? — EMPraptor, Oct 29 '09 at 15:32
I updated the question to show that I'm merely using the cgi and cgitb modules for Python along with IIS7. Nothing special. — Mike Caron, Oct 29 '09 at 15:55

score 3 · Answer 1 · answered May 29 '12 at 06:13

3

Start your script with: cgitb.enable() Then to output a correct error code during an exception use:

try:
  blah blah failed code
except:
  print "Status: 500"
  cgitb.handler()

answered May 29 '12 at 06:13

w00kie

301
2
3

score 3 · Accepted Answer · edited May 23 '17 at 11:55

It seems like that's the way to do it. As long as you're correctly following the header format.

Here's someone else who asked the same question, more or less.

Returning http status codes in Python CGI

Are you following HTTP specs when you print the status code? Can you try printing just the status code and not its description?

Maybe like...

print '''Status:501
Content-type: text/html

'''

Or it should be like...

print '''HTTP/1.1 501 Not Implemented
Content-type: text/html

'''

Could you test with your setup to verify?

Returning status from CGI:

http://oreilly.com/openbook/cgi/ch03_07.html

I guess "Status: 501 Not Implemented" like you had it originally is the way to go. I don't know why it's not working. Are you printing any non-header content before printing the status code?

Yet another source that confirms you're doing it right (look in section 6.3.3.):

http://www.ietf.org/rfc/rfc3875

EDIT 1,2,3: extended answer

score 0 · Answer 3 · edited May 23 '17 at 12:30

Python CGI returning an http status code, such as 403?

One answer suggested there:

sys.stdout('Status: 403 Forbidden\r\n\r\n')

may be technically more correct, according to RFC (assuming that your CGI script isn't running in text mode on Windows). However both line endings seem to work everywhere.

But since you're doing this on windows and you're not ending the header with the status line...

sys.stdout('Status: 501 Not Implemented\n')

I don't see why using sys.stdout would matter though since print should be using stdout.

How do I raise an http error/exception from a python CGI script?

3 Answers3