[mod_python] Simple Issue, Baffling

Jim Gallacher jpg at jgassociates.ca
Thu Jan 26 16:51:02 EST 2006

David Worley wrote:
> To clarify further:
> http://localhost/some/file/system/directory/style.css is only ever
> called from an HTML file, via a <link> tag. 

I figured you knew that, but one never knows. ;)

> The HTML is valid. The HTML
> page is NOT generated by mod_python. It's just a plain HTML file in the
> folder. I created it just for testing dynamically created CSS files.
> The separate issue of "text/html" content is, indeed, handled by another
> handler. The two are unrelated. When text/css content wouldn't work, I
> tried something simpler: plain HTML return content.
> Simply put, req.write(xxx) returns content that my browser does not make
> use of, whether CSS or HTML, despite the explicit declaration of
> req.content_type. The browser just thinks it's text.
> It may be more accurate to say that the server never returns HTML or
> CSS, rather than saying that the browser never renders the file
> returned.

Is your handler as simple as you indicated or is there other stuff going 
on? Any chance you are calling req.write *before* setting 
req.content_type? The first call to req.write triggers the sending of 
the response headers, which contains the Content-Type header. Once 
you've starting calling req.write changing req.content_type will have no 
effect. (Hmm, I wonder if we should actually raise an exception... )

I find that tools like wget or netcat are helpful for this sort of thing 
since you can dump the response headers as well as the page content. If 
you don't have ready access to these programs I'm sure you could know 
somthing together from the standard python lib. Sometimes the simplest 
problems have the simplest solutions.


> ===============================
> David Worley
> Senior Front End Developer
> dworley at communityconnect.com
> =============================== 
> -----Original Message-----
> From: Jim Gallacher [mailto:jpg at jgassociates.ca] 
> Sent: Thursday, January 26, 2006 4:15 PM
> To: David Worley
> Cc: mod_python at modpython.org
> Subject: Re: [mod_python] Simple Issue, Baffling
> David Worley wrote:
>>Hello, all. I'm new to mod_python and somewhat new to server side
>>I've read the documentation, and I can't seem to find out something
>>relatively simple.
>>I'm writing a CSS preprocessor. It's meant to grab a request for a
> .css
>>file, process another file and return the result to the browser. The
>>issue I have is that I can't get the handler to return content the
>>browser actually uses.
>>To clarify, I'm running Apache 2.0, Python 2.4 on Windows XP.
>>So with the following httpd.conf entry:
>><Directory /some/file/system/directory>
>>	AddHandler python-program .sss
>>	PythonHandler switch
>>	PythonDebug On
>>And the following Python code, in switch.py:
>>from mod_python import apache
>>def handler(req):
>>	req.content_type = "text/css"
>>	req.write("""\
>>body { background-color: red; }""")
>>	return apache.OK
>>This works. It works great. When I request
>>http://localhost/some/file/system/directory/style.css, I get the body
>>declaration above. BUT the browser doesn't use it!
> Maybe I don't understand the question but why would it? The browser only
> uses the stylesheet to render the page when it's specified in an html 
> <style> tag.
>>I have the same problem when declaring req.content_type = "text/html":
>>the code is returned properly, but it isn't rendered as HTML. It's
> just
>>text, as far as the browser is concerned.
> You got me there, unless you are saying you are getting the python code 
> as opposed to the html you send with req.write. Are you writing valid 
> html? Any chance there is a typo in req.content_type = 'text/html'? Are 
> you using a different handler for generating the html?
> It would help if you can clarify your problem a little.
> Jim
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