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http://issues.apache.org/jira/browse/MODPYTHON-98?page=comments#action_12360190
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Graham Dumpleton commented on MODPYTHON-98:
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In respect of SILENT and return of apache.DECLINED, if it is desired that it
truly be silent like the documentation says it will be, then in
CallBack.HandlerDispatch of mod_python.apache, then instead of:
elif hlist.silent:
result = DECLINED
it probably should read:
elif hlist.silent:
if result != OK:
result = DECLINED
By doing this, it means that a handler which could not be found, but which
followed on from a previous handler, will not replace the OK result of the
previous handler with DECLINED.
The only time the result would be set to DECLINED would be where the handler
which could not be found was the first handler in a list of handlers. In that
case, a subsequent handler could still set result to OK or generate some other
result. The DECLINED result of the missing handler would only propogate back if
there was no subsequent handler.
Thus the above would be the appropriate change were you to want it to be silent
like the documentation says. I still perhaps feel that it shouldn't be silent
though and it should generate an error, else the problem in the code wouldn't
be picked up but would otherwise appear to run. Thus still vote for NOTSILENT.
:-)
> wrong handler supplied to req.add_handler() generates error
> -----------------------------------------------------------
>
> Key: MODPYTHON-98
> URL: http://issues.apache.org/jira/browse/MODPYTHON-98
> Project: mod_python
> Type: Bug
> Components: core
> Versions: 3.2, 3.1.4
> Reporter: Graham Dumpleton
>
> The documentation for req.add_handler() states:
> Note: There is no checking being done on the validity of the handler name.
> If you pass this function an invalid handler it will simply be ignored.
> In other words, get the name of the handler wrong and it is supposed to just
> ignore it. This is not actually the case, instead it will generate an
> exception when it goes to process the handler:
> Mod_python error: "PythonHandler example::handler_3"
> Traceback (most recent call last):
> File
> "/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/site-packages/mod_python/apache.py",
> line 291, in HandlerDispatch
> arg=req, silent=hlist.silent)
> File
> "/System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/site-packages/mod_python/apache.py",
> line 538, in resolve_object
> raise AttributeError, s
> AttributeError: module '/Users/grahamd/Sites/add_handler/example.py'
> contains no 'handler_3'
> This can be seen with .htaccess file of:
> SetHandler mod_python
> PythonAccessHandler example
> PythonHandler example::handler_1
> PythonDebug On
> and example.py file containing:
> from mod_python import apache
> def accesshandler(req):
> apache.log_error("accesshandler")
> req.add_handler("PythonHandler","example::handler_3")
> return apache.OK
> def handler_1(req):
> apache.log_error("handler_1")
> req.content_type = 'text/plain'
> req.write("HELLO")
> return apache.OK
> def handler_2(req):
> apache.log_error("handler_2")
> return apache.OK
> Either the documentation is wrong and an exception is desired, or more likely
> this is an extension of the prior problem with hlist.silent as described as
> being a problem in other ways in MODPYTHON-46.
> In that case the logic of SILENT/NOTSILENT was the wrong way around and it
> was fixed by reversing the definitions of the two. In doing this though, it
> didn't cover cases where a "silent" flag is passed to hlist_new() and
> hlist_append() in the req_add_handler() function of requestobject.c.
> Specfically, there are calls to hlist_new() and hlist_append() in that
> function:
> hlist_append(self->request_rec->pool, self->hlo->head,
> handler, dir, 0);
> hle = hlist_new(self->request_rec->pool, handler, dir, 0);
> hlist_append(self->request_rec->pool, hle, handler, dir, 0);
> These should be written as:
> hlist_append(self->request_rec->pool, self->hlo->head,
> handler, dir, SILENT);
> hle = hlist_new(self->request_rec->pool, handler, dir, SILENT);
> hlist_append(self->request_rec->pool, hle, handler, dir, SILENT);
> If this change were made, the code would then behaves conformant with the
> documentation as far as being silent, however it highlights a further issue.
> This further issue is that although it is silent when the handler name is
> wrong, this results in apache.DECLINED being returned for the handler that
> couldn't be found. Because apache.DECLINED is returned, Apache will try and
> interpret the URL again and if possible serve up a static file etc.
> For the above example code this then means that if "example.py" was used in
> the URL, the browser gets back a response of:
> HELLOfrom mod_python import apache
> def accesshandler(req):
> apache.log_error("accesshandler")
> req.add_handler("PythonHandler","example::handler_3")
> return apache.OK
> def handler_1(req):
> apache.log_error("handler_1")
> req.content_type = 'text/plain'
> req.write("HELLO")
> return apache.OK
> def handler_2(req):
> apache.log_error("handler_2")
> return apache.OK
> That is, the content as returned by handler_1(), followed by the contents of
> the example.py file.
> If instead the URL wasn't 'example.py' but say 'other.py' with that not
> existing, get back:
> HELLO
> OK
> The requested URL /~grahamd/add_handler/foo.py was not found on this server.
> Apache/2.0.51 (Unix) mod_python/3.2.5b Python/2.3 Server at localhost Port
> 8080
> In some ways, this behaviour suggests that the behaviour whereby it raised an
> exception was probably a better way of handling the situtation anyway. Thus,
> maybe the documentation should instead be changed and the code left as is, or
> at least the 0 arguments changed to be NOTSLIENT to make it more obvious what
> it is doing.
> The other option is to change the code to use SILENT, but then document the
> strange things that can result if the specified handler doesn't exist.
> Comments??????
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