Hi
I had that same problem :-)
The problem is that you declare are mapping to class that already has
mapper defined for it.
To work around this, I declared the class i mapped inside a function
so a new class is defined every time i need to create a mapper.
Where as before, When the module was loaded, The class i mapped was
defined one and that was the only instance of the definition.
(Probably using all the wrong python terminology)
I did something like this
def create_mapper_function(self, engine, metadata_table):
class OrmRecord(object):
pass
self._OrmRecord = OrmRecord
mapper(self._OrmRecord, metadata_table)
To create a new record
def create_new(self):
# The instance of the definition that is mapped is
# self._OrmRecord
# Create a new instance of the mapped class
orm_record = self._OrmRecord()
# populate and store
orm_record.field1 = 'Yo'
session.add(orm_record)
This works well for me, Not sure if its the correct way to do it.
On Mar 29, 3:51 pm, Opus <[email protected]> wrote:
> Hello,
>
> I'm a sqlalchemy newbie and I'm trying to get a handle on how and
> where to do the mappers in my app.
>
> The app consists of a frame > split window > tree control & flat
> notebook.
>
> The idea is that when you click on a node in the tree, the record is
> opened in a new tab in the flat notebook.
>
> I decided to try and use sqlalchemy orm to handle all the db
> operations but I'm having a bit of trouble.
>
> I can get it to open up and disply the first record that I select from
> the tree but if I try to open a second (different) record I get the
> following error from sqlalchemy:
>
> File "c:\program files\python25\lib\site-packages\sqlalchemy-0.5.2-
> py2.5.egg\sqlalchemy\orm\mapper.py", line 351, in
> _configure_class_instrumentation
> self.class_)
> sqlalchemy.exc.ArgumentError: Class '<class 'Gui.Person.Person'>'
> already has a primary mapper defined. Use non_primary=True to create a
> non primary Mapper. clear_mappers() will remove *all* current mappers
> from all classes.
>
> In my main app I connect to the db, create a session, set up the
> metadata and load all the table metadata.
>
> The main app then sets up the frame which proceeds to fill my tree.
>
> When the user clicks on a node a notebook page is created which then
> maps the class to the table, reads the record and displays it. That
> works fine until I try to create a new instance of the page with a
> different record.
>
> In brief the question is, "where in a gui app should I do the
> mapping?"
>
> Thanks in advance
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