[storm] String Representation of keys

[Christian Klinger]

Hi,

first it´s hard for me to explain what i need. So i hope you can 
understand my problems.

I try to develope a "storm container" for zope.
I use the zalchemy product as a base for my work with storm.

I run into some Problems when i try to build a uri for my objects.

An example:

http://localhost/app/Person-(1,)

In uri consists of these relevant parts for me:

    app is the container
    Person is the classname of my Object
    (1,) these are the primary keys of my object

Currently i construct the primary key in this way:

     def _toStringIdentifier(self, obj):
         """ Construct the PrimaryKey"""
         store = getUtility(IZStorm).get(self.getStoreUtilityName())
         ident = self._getInstanceKey(obj)
         prefix = "%s-" %self._class.__name__
         return "%s%s" %(prefix, ident)

     def _getInstanceKey(self, obj):
         """ Get an unique id form obj """
         obj_info = get_obj_info(obj)
         id = tuple(obj_info.variables[column].get() for column in 
obj_info.cls_info.primary_key)
         return id


The code for getting an object back looks like this:

     def _fromStringIdentifier(self, name):
         prefix = "%s-" %self._class.__name__
         if not str(name).startswith(prefix):
             return None
         store = getUtility(IZStorm).get(self.getStoreUtilityName())
         id = name[ len(str(self._class.__name__)) + 1: ]
         key = self.str2tuple(id)
         return store.get(self._class, key)


     def str2tuple(self,s):
         """Convert tuple-like strings to real tuples.
         eg '(1,2,3,4)' -> (1, 2, 3, 4)
         """
         if s[0] + s[-1] != "()":
             raise ValueError("Badly formatted string (missing brackets).")
         items = s[1:-1]  # removes the leading and trailing brackets
         if items.endswith(','):
             items = items[:-1]
         items = items.split(',')
         L = [int(x) for x in items] # clean up spaces, convert to ints
         return tuple(L)


I know this is very ugly but i don´t find a better way for doing this
maybe someone of you has an better idea of doing this.

I have created a doctest for the container maybe this gives you
a better impression how it works and what the problems are.

http://stormcontainer.googlecode.com/svn/trunk/src/megrok/storm/tests/stormcontainer.txt

Christian