[sqlalchemy] Re: synonyms question
On Jul 7, 2008, at 3:29 PM, Eric Lemoine wrote:
Hello
To override attribute behavior the 0.5 doc gives this example:
class MyAddress(object):
def _set_email(self, email):
self._email = email
def _get_email(self):
return self._email
email = property(_get_email, _set_email)
mapper(MyAddress, addresses_table, properties = {
'email':synonym('_email', map_column=True)
})
What won't work if I just set the python property and don't use the
synonym func:
mapper(MyAddress, addresses_table)
What difference does it make? I couldn't find an explanation in the
doc.
Sorry if that's a dumb question!
without synonym(), just add _email:addresses_table.c.email to your
mapper properties dict so that the email name is made available.
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[sqlalchemy] Re: synonyms question
On Mon, Jul 7, 2008 at 10:24 PM, Michael Bayer [EMAIL PROTECTED] wrote:
On Jul 7, 2008, at 3:29 PM, Eric Lemoine wrote:
Hello
To override attribute behavior the 0.5 doc gives this example:
class MyAddress(object):
def _set_email(self, email):
self._email = email
def _get_email(self):
return self._email
email = property(_get_email, _set_email)
mapper(MyAddress, addresses_table, properties = {
'email':synonym('_email', map_column=True)
})
What won't work if I just set the python property and don't use the
synonym func:
mapper(MyAddress, addresses_table)
What difference does it make? I couldn't find an explanation in the
doc.
Sorry if that's a dumb question!
without synonym(), just add _email:addresses_table.c.email to your
mapper properties dict so that the email name is made available.
In that case, on DB read, SA will set _email directly and won't go
through _set_email(). Is that correct?
And with email:synonym('_email', map_column=True), will SA set
_email directly or will it go through _set_email()? My feeling is that
it will set it directly, so it is exactly the same as doing
_email:addresses_table.c.email.
And if one uses neither email:synonym('_email', map_column=True) nor
_email:addresses_table.c.email then SA will go through _set_email().
Is my understanding correct?
--
Eric
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[sqlalchemy] Re: synonyms question
On Jul 7, 2008, at 5:46 PM, Eric Lemoine wrote:
without synonym(), just add _email:addresses_table.c.email to your
mapper properties dict so that the email name is made available.
In that case, on DB read, SA will set _email directly and won't go
through _set_email(). Is that correct?
yes.
And with email:synonym('_email', map_column=True), will SA set
_email directly or will it go through _set_email()? My feeling is that
it will set it directly, so it is exactly the same as doing
_email:addresses_table.c.email.
the mapper will always set _email directly. It never goes through
user-defined descriptors since it is essentially writing to
obj.__dict__ directly.
If you want Python code to take effect for data as it leaves the
database, you might look into creating a TypeDecorator with the
desired behavior.
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[sqlalchemy] Re: synonyms question
On Mon, Jul 7, 2008 at 11:51 PM, Michael Bayer [EMAIL PROTECTED] wrote:
On Jul 7, 2008, at 5:46 PM, Eric Lemoine wrote:
without synonym(), just add _email:addresses_table.c.email to your
mapper properties dict so that the email name is made available.
In that case, on DB read, SA will set _email directly and won't go
through _set_email(). Is that correct?
yes.
And with email:synonym('_email', map_column=True), will SA set
_email directly or will it go through _set_email()? My feeling is that
it will set it directly, so it is exactly the same as doing
_email:addresses_table.c.email.
the mapper will always set _email directly. It never goes through
user-defined descriptors since it is essentially writing to
obj.__dict__ directly.
If you want Python code to take effect for data as it leaves the
database, you might look into creating a TypeDecorator with the
desired behavior.
That explains it all. Thanks Michael.
--
Eric
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