Webware for Python

At 08:55 PM 6/28/2001 -0700, haaserd wrote:
>I first placed them in my within my project directory which
>is not a branch of the Webware directory.  This caused a
>problem because when my script was executed, the CWD was
>/webware (not my project directory) and the traceback ended
>with:
>
>   File "MiscUtils\DataTable.py", line 293, in readFileNamed
>     file = open(self._filename, 'r')
>IOError: [Errno 2] No such file or directory:
>'PetroDB.mkmodel\\Classes.csv'

This is just simply a filename issue. In any Python program, you can use 
relative filenames if they are correct for your cur dir. Otherwise use an 
abs path.

Since your MiddleKit model is more likely to be located next to your WebKit 
context, than next to your Webware installation, you want to use that.

Suppose your MK directory is next to your WebKit context like so:
MyApp/
     MyApp.mkmodel/
     Context/
         Main.py
         __init__.py


In __init__.py you could take the dirname(dirname()) of the __file__ and 
add on 'MyApp.mkmodel' to get the right path.

Under no circumstance do I recommend writing WebKit code that relies on the 
current directory. Inevitably 2 separate bodies of code will start fighting 
over this.


>My second question is why the use of (from the Quick Start
>Guide) video.serialNum() when the corresponding MySQL table
>name is videoId?  Wouldn't accessing it with video.videoId()
>or naming it serialNum be less confusing?

Someone talked me into using videoId instead of serialNum for reasons I 
forget. If no one has any objections, I would be fine with changing it to 
serialNum.


-Chuck

Sorry if I didn't do enough research and make my first question clear the first
time around.

It was MiscUtils/DataTable.py that was trying to load xxx.mkmodel/Classes.csv
that gave me the problem.  DataTable.py at line 293 does an open for the
relative filename 'xxx.mkmodel/Classes.csv'.  My script did not modify the CWD
and it was pointing to /python/webware at the point of failure.

(When I did modify the CWD to fix the above problem, something else broke - I
won't do that again.)

So I think my answer is the directory xxx.mkmodel/ must be placed in or copied
to the directory
/python/webware and the CWD must not be changed by any script (before
connecting to the MySQL database by calling MySQLObjectStore and
.readModelFileNamed).  If that were documented in Quick Start, I would be
happy.  Else DataTable.py must figure out the absolute address of the
Classes.csv file used by the generate process.

Your answer confused me.  I downloaded and installed Webware/WebKit as a
(stable, yes I realize it is beta) Python application so I have the structure
/Python/Webware/WebKit.  My code is not on the Python directory branch.

I think your answer said you are developing WebKit along with another
application, and have WebKit installed off the Python directory branch in an
application directory.  Your different directory structure may be yielding
different results.

Roger Haase



Chuck Esterbrook wrote:

> At 08:55 PM 6/28/2001 -0700, haaserd wrote:
> >I first placed them in my within my project directory which
> >is not a branch of the Webware directory.  This caused a
> >problem because when my script was executed, the CWD was
> >/webware (not my project directory) and the traceback ended
> >with:
> >
> >   File "MiscUtils\DataTable.py", line 293, in readFileNamed
> >     file = open(self._filename, 'r')
> >IOError: [Errno 2] No such file or directory:
> >'PetroDB.mkmodel\\Classes.csv'
>
> This is just simply a filename issue. In any Python program, you can use
> relative filenames if they are correct for your cur dir. Otherwise use an
> abs path.
>
> Since your MiddleKit model is more likely to be located next to your WebKit
> context, than next to your Webware installation, you want to use that.
>
> Suppose your MK directory is next to your WebKit context like so:
> MyApp/
>      MyApp.mkmodel/
>      Context/
>          Main.py
>          __init__.py
>
> In __init__.py you could take the dirname(dirname()) of the __file__ and
> add on 'MyApp.mkmodel' to get the right path.
>
> Under no circumstance do I recommend writing WebKit code that relies on the
> current directory. Inevitably 2 separate bodies of code will start fighting
> over this.
>
> >My second question is why the use of (from the Quick Start
> >Guide) video.serialNum() when the corresponding MySQL table
> >name is videoId?  Wouldn't accessing it with video.videoId()
> >or naming it serialNum be less confusing?
>
> Someone talked me into using videoId instead of serialNum for reasons I
> forget. If no one has any objections, I would be fine with changing it to
> serialNum.
>
> -Chuck
>
> _______________________________________________
> Webware-discuss mailing list
> Webware-discuss@...
> http://lists.sourceforge.net/lists/listinfo/webware-discuss


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I looked over Generate.py and DataTable.py a bit.  Seems like whatever data
DataTable.py is trying to provide should be captured earlier by Generate.py and
placed in a module in the GeneratedPy/ directory.  This would eliminate the problem
of trying to open Classes.csv with a relative address, make the operation slightly
faster as Classes.csv is not cacheable and the Python module would be, and
eliminate a potential problem where users (such as me) update Classes.csv as
thoughts occur and re-generate only when no further testing can be done with the
current data structure.

Unfortunately, coding that up is beyond my present ability.

Roger Haase


haaserd wrote:

> .readModelFileNamed).  If that were documented in Quick Start, I would be
> happy.  Else DataTable.py must figure out the absolute address of the
> Classes.csv file used by the generate process.


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At 05:09 PM 6/30/2001 -0700, haaserd wrote:
>So I think my answer is the directory xxx.mkmodel/ must be placed in or copied
>to the directory
>/python/webware and the CWD must not be changed by any script (before
>connecting to the MySQL database by calling MySQLObjectStore and
>.readModelFileNamed).  If that were documented in Quick Start, I would be
>happy.  Else DataTable.py must figure out the absolute address of the
>Classes.csv file used by the generate process.

Actually it's *you* that must either:

* Pass an absolute path that is valid.

* Pass a relative path that is valid.


MiddleKit and DataTable aren't/can't be smart enough to find your model. 
Think of it as a Python open() (which does in fact happen down in the 
guts). Only what would work for open() will work when you pass in the path 
to your model.

Since this is file system stuff and people structure their files in 
different ways, this varies from person to person.

However, it is certainly true that MK deserves an "integrating with WebKit 
section".


-Chuck

At 01:38 PM 7/1/2001 -0700, haaserd wrote:
>I looked over Generate.py and DataTable.py a bit.  Seems like whatever data
>DataTable.py is trying to provide should be captured earlier by 
>Generate.py and placed in a module in the GeneratedPy/ directory.  This 
>would eliminate the problem of trying to open Classes.csv with a relative 
>address, make the

The problems of importing the MK-generated classes and opening the .csv are 
similar. In the first case, you must put the classes where they can be 
found or augment PYTHONPATH/sys.path. In the second case, you must specify 
a valid path (whether you prefer relative or absolute is your choice).

There might be a shift here, but there wouldn't be less to consider and 
configure.


>operation slightly faster as Classes.csv is not cacheable and the Python

Any .csv is cacheable by simply keeping the data in memory (such as an 
instance of DataTable). In this particular case, MK creates a series of 
Klass and Attr objects (found in MiddleKit.Core) which are in fact cached 
in memory for the lifetime of the model (which is typically the lifetime of 
the store that uses the memory). The .csv is thrown away as it is merely a 
means to convey the model. Other means such as XML could be introduced in 
the future without disturbing the rest of MiddleKit.

Perhaps it could make start up faster if the Model was pickled to disk and 
read in lieu of the .csv spec provided the .csv date was older. I've added 
that to the TO DO list as a potential optimization.


>module would be, and eliminate a potential problem where users (such as 
>me) update Classes.csv as thoughts occur and re-generate only when no 
>further testing can be done with the current data structure.

Is there any reason not to generate after editing the .csv?

If there is, you might consider a separate file for your thoughts which you 
then copy over before generating. Of course, you can make a little script 
to do the copy and the generate:

#!/bin/sh
# gen
cp Classes.csv Classes.bak
cp NewClasses.csv Classes.csv
python path/to/MiddleKit/Design/Generate.py --db MySQL --model MyApp.mkmodel


Then just type this when you want:
 > gen


Hope that helps.


-Chuck