string join() method

[Derek Basch]

Can anyone tell me why this CGI code outputs a blank page?
--------------------------------
self.output = []
self.setContent Type("text/plain")
ascii_temp.seek (0)
self.output.ext end(ascii_temp. read())
print ''.join(self.ou tput)

def setContentType( self, type="text/xml"):
self.output.ext end(["Content-type: ", type, "\n\r"])
---------------------------------

but this code works?:
---------------------------------
self.output = []
self.setContent Type("text/plain")
print ''.join(self.ou tput)
ascii_temp.seek (0)
print ascii_temp.read ()

def setContentType( self, type="text/xml"):
self.output.ext end(["Content-type: ", type, "\n\r"])
---------------------------------

ascii_temp is just some tab seperated data:
---------------------------------
Allele Seq:Start-End Length Sequence Score
A01 1: 1-8 8 SSSSSSSS 1410538.0
A01 1: 2-9 8 SSSSSSSS 1410538.0
---------------------------------

Thanks everyone.
Derek Basch

[Benjamin Niemann]

Re: string join() method

Derek Basch wrote:
[color=blue]
> Can anyone tell me why this CGI code outputs a blank page?
> --------------------------------
> self.output = []
> self.setContent Type("text/plain")
> ascii_temp.seek (0)
> self.output.ext end(ascii_temp. read())
> print ''.join(self.ou tput)
>
> def setContentType( self, type="text/xml"):
> self.output.ext end(["Content-type: ", type, "\n\r"])
> ---------------------------------
>
> but this code works?:
> ---------------------------------
> self.output = []
> self.setContent Type("text/plain")
> print ''.join(self.ou tput)
> ascii_temp.seek (0)
> print ascii_temp.read ()
>
> def setContentType( self, type="text/xml"):
> self.output.ext end(["Content-type: ", type, "\n\r"])
> ---------------------------------
> [snip][/color]

First thing: HTTP header lines must be terminated by "\r\n" not "\n\r".
The headers are terminated by another "\r\n". I'm not sure (but I would bet
an Euro or two that it does), but perhaps the webserver sanitizes the
output of CGI script and converts plain "\n" into "\r\n" - if not then you
shouldn't use print to output the headers, because it only outputs
non-HTTPish "\n".

The output of your first script is

---------------------------------------
Content-type: text/plain\r\n
Allele...
---------------------------------------

whereas the second script outputs

---------------------------------------
Content-type: text/plain\r\n
\n
Allele...
---------------------------------------

The (required) "\n" - that should also be an "\r\n" - seperating the headers
from the content is added by the first print.

--
Benjamin Niemann
Email: pink at odahoda dot de
WWW: http://www.odahoda.de/

[Damjan]

Re: string join() method

> but perhaps the webserver sanitizes the output of CGI script and converts[color=blue]
> plain "\n" into "\r\n"[/color]

Yes apache does this, since it adds its own headers anyway it will replace
all '\n' in the headers with '\r\n' and '\n\n' with '\r\n\r\n'.


--
damjan

[Kent Johnson]

Re: string join() method

Derek Basch wrote:[color=blue]
> Can anyone tell me why this CGI code outputs a blank page?[/color]

Maybe because it needs a blank line between the header and the body?
[color=blue]
> --------------------------------
> self.output = []
> self.setContent Type("text/plain")
> ascii_temp.seek (0)
> self.output.ext end(ascii_temp. read())[/color]
self.output.app end() is probably what you mean. Try this:

self.output.app end('\r\n')
self.output.app end(ascii_temp. read())
[color=blue]
> print ''.join(self.ou tput)
>
> def setContentType( self, type="text/xml"):
> self.output.ext end(["Content-type: ", type, "\n\r"])
> ---------------------------------
>
> but this code works?:
> ---------------------------------
> self.output = []
> self.setContent Type("text/plain")
> print ''.join(self.ou tput)[/color]
The above line will create a blank line because of the extra newline from print.

Kent
[color=blue]
> ascii_temp.seek (0)
> print ascii_temp.read ()
>
> def setContentType( self, type="text/xml"):
> self.output.ext end(["Content-type: ", type, "\n\r"])
> ---------------------------------
>
> ascii_temp is just some tab seperated data:
> ---------------------------------
> Allele Seq:Start-End Length Sequence Score
> A01 1: 1-8 8 SSSSSSSS 1410538.0
> A01 1: 2-9 8 SSSSSSSS 1410538.0
> ---------------------------------
>
> Thanks everyone.
> Derek Basch
>[/color]