Re: Regex based publisher proposal
Thank you all for taking the time to read my code, I apologize for not including a better description of what I intended to do, but I was reluctant to post a very very long message to the list to start with, so I am going to blame my poor editing skills and the late hour I sent this email at ;) In short, Nicolas did read my mind correctly in regards to what I am attempting to do here. I have searched and searched like many python developers for a proper web framework and I have settled for mod_python about 2 years ago. I tried afterwards the new popular ones such as Ruby on Rails, TurboGears, Django, but not really liked those because mostly with their integration with SQL Objects type DB abstraction, which I never bought into, and their dependence on specific templating systems. Nevertheless, they did introduce some interesting concepts (such as regex url mapping), which I am attempting here (poorly it seems) to implement directly in mod_python. To put things back into context, the code I submitted was a simple draft from a passion impulse over the labor day week-end and was never (in my mind) a solid implementation but more something to illustrate what could maybe done and open a discussion. To review quickly the code comments though, the mapper_cache object is not thread safe yet, and I added only later the ability to define your regex as a PythonOption argument and definetly forgot to consider what could happen when two different parts of the URL namespace use different regex's and don't execute in different Python interpreter instances. In regards to: path,module_name = os.path.split(req.filename) # Trimming the front part of req.uri if module_name=='': req_url = '' else: req_url = req.uri[req.uri.index(module_name):] It is bringing a question I have had for a long time in mod_python. Is there a way to identify accurately the relative virtual path of a request other than comparing to the physical path, especially when using apache definition such as VirtualHost Location? For example let's say you define something like: Location /myapp/admin/ AddHandler mod_python .py .html PythonHandler mod_python.publisher /Location And there comes a request such as http://myserver/myapp/admin/login.html How do you determine accurately that the part of the path /myapp/ admin/ is in fact the virtual root of your application ? Also, a little bit trickier when you get something like: http:// myserver/myapp/admin/display/asc/xxx 1) Is the only way to pass along all requests (not filtered by extensions) to your mod_python handler is to use something like: SetHandler python-program PythonHandler myhandler 2) In this situation determining the virtual root of your application is crucial to be able to separate the regular path from the potential parameters/actions so how would you go about it? I have in the past used the cheap trick of passing along in a PythonOption the virtual path of my app, but there must be a better way. I have still failed though to find in the mod_python docs a way to read the properties of an apache location or virtual host directive in order to determine automatically the proper virtual root of my handler. Graham, I chose to re-embedded the code of mod_python publisher, mainly because I figured I would have to modify some other parts, if I want to not only publish a function, but in fact publish a callable class (which would derive from a future mywebframework.action class). Correct me if I am wrong, but right now it is not possible to publish a callable class in a module with mod_python publisher. Jorey, I dig your implementation without using regex, but here I am really trying to use regex. I also thought that performance would be an issue, but on some of my early benchmarks I did not get any worse performance than the current mod_python.publisher method. So, I think that if implemented properly performance might not even be drawback of using regex. Finally, all I am really trying to build here is a drop-in replacement for mod_python.publisher by providing by default the same functionality, but to offer the flexibility found in newer web frameworks via regex mapping and eventually implement a reverse url mapping method, just like Nicolas described it. I have looked closely at routes, but I did not want all the features they implemented and did not like the idea of adding an external dependency just for the routing/mapping process. I strongly believe in a simple mod_python web framework that would arm developers with essential tools such as: * regex based routing with a reverve mapping method * web object oriented (a request maps to a class instanced for the call) * regex based parameter validation (to insure the good form of data passed along ) * DB connection pooling * Generic rendering template
Re: Regex based publisher proposal
On 08/09/2006, at 2:53 PM, Sébastien Arnaud wrote:
In short, Nicolas did read my mind correctly in regards to what I
am attempting to do here. I have searched and searched like many
python developers for a proper web framework and I have settled for
mod_python about 2 years ago. I tried afterwards the new popular
ones such as Ruby on Rails, TurboGears, Django, but not really
liked those because mostly with their integration with SQL Objects
type DB abstraction, which I never bought into, and their
dependence on specific templating systems. Nevertheless, they did
introduce some interesting concepts (such as regex url mapping),
which I am attempting here (poorly it seems) to implement directly
in mod_python.
I'd still appreciate an English description with examples as I
haven't delved too
much into some of these other packages. Ie., what does the URL look
like for
a concrete example, and how does that relate to what files Apache may
match
in the file system and subsequently what may be interpreted within
the handler
from the path info.
I know I could probably sit down and work it out, but my excuse is I
am not well,
even had to take a couple days off work, so not thinking too
straight. ;-)
To put things back into context, the code I submitted was a simple
draft from a passion impulse over the labor day week-end and was
never (in my mind) a solid implementation but more something to
illustrate what could maybe done and open a discussion.
My feedback was intended to be constructive, not critical. :-)
In regards to:
path,module_name = os.path.split(req.filename)
# Trimming the front part of req.uri
if module_name=='':
req_url = ''
else:
req_url = req.uri[req.uri.index(module_name):]
It is bringing a question I have had for a long time in mod_python.
Is there a way to identify accurately the relative virtual path of
a request other than comparing to the physical path, especially
when using apache definition such as VirtualHost Location? For
example let's say you define something like:
Location /myapp/admin/
AddHandler mod_python .py .html
PythonHandler mod_python.publisher
/Location
And there comes a request such as http://myserver/myapp/admin/
login.html
How do you determine accurately that the part of the path /myapp/
admin/ is in fact the virtual root of your application ?
If a Directory directive is used, or the handler directives appear in
a .htaccess file,
the you can use req.hlist.directory.
Caveats to this are that prior to mod_python 3.3, if the handler
directive appears
inside of a Files/FileMatch directive within those two contexts, the
value was wrong
and could not be used. Further, prior to mod_python 3.3, the result
would be wrong
if use wildcards in the Directory directive, or the DirectoryMatch
variant was used.
When the Location directive is used, there is no physical directory
which corresponds
to it and so req.hlist.directory wouldn't be valid as its purpose is
to denote the physical
directory a directive was associated with. A caveat to this though,
is that prior to
mod_python 3.3, req.hlist.directory would actually list the path
specified in the
Location directive. This isn't the case though in mod_python 3.3 and
it will instead
be None when used in the Location or LocationMatch directives as it
causes problems
otherwise with a non existent path being used as a location to search
for Python
modules.
With my brain being clouded at the moment, I cant remember off the
top of my head
what the correct way is and I would have to check things, but when
you use the
Location directive, isn't req.path_info the part of the URL which
lies below where the
Location directive was specified for. If my memory is correct, this
doesn't mean you
can simply take the length of req.path_info and drop off that much
off req.uri though.
The problem is that req.uri isn't normalised in the way that
req.path_info is, so it may
contain repeating slashes and other crud that can stuff things up.
You need to address
that before you can use it.
Also, a little bit trickier when you get something like: http://
myserver/myapp/admin/display/asc/xxx
1) Is the only way to pass along all requests (not filtered by
extensions) to your mod_python handler is to use something like:
SetHandler python-program
PythonHandler myhandler
In mod_python 3.3, you will be able to specify a fixup handler which
did:
def fixuphandler(req):
req.handler = 'mod_python'
req.add_handler('PythonHandler', 'myhandler')
return apache.OK
The bit that doesn't work before mod_python 3.3 is the assignment to
the req.handler
attribute, with it being read only in older versions.
In mod_python 3.3, when using req.add_handler(), the handler need not
even be a
string, but could be an actual callable object.
I still haven't quite finished the article, nor
