[sqlalchemy] Re: inferring object class/table directly
On Tue, 2 Dec 2008 at 23:21, Faheem Mitha wrote: Yes, I was looking for this, and printed out obj.__dict__ but didn't see it there. A dictionary of attributes is very useful in theory, but doesn't always seem to have all attributes. Is this documented anywhere? Try dir(obj). You'll see it there. The __dict__ is only for instance attributes. Not too difficult. You can also use type(obj) instead of obj.__class__. I thought of trying this, but didn't. It didn't seem likely to work, anyway. Is either of these preferred over the other in terms of API stability, and if so, why? obj.__class__ is a python thing, as is type(obj), and neither of those is changing in python 3.0, so I'd think both would be stable API wise :) However, the documentation of __class__ makes it clear you get the class back, while the documentation of the 'type' built in function does not...so I'd lean toward using __class__, myself. It also means you'll get an earlier error if you accidentally pass something that is not actually a class instance into your function. --RDM --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: inferring object class/table directly
On Wed, 3 Dec 2008 08:58:42 -0500 (EST), [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: On Tue, 2 Dec 2008 at 23:21, Faheem Mitha wrote: Yes, I was looking for this, and printed out obj.__dict__ but didn't see it there. A dictionary of attributes is very useful in theory, but doesn't always seem to have all attributes. Is this documented anywhere? Try dir(obj). You'll see it there. The __dict__ is only for instance attributes. Excellent. This is the first I've heard of this function, but apparently it is a Python builtin. Well past time to go read the docs for this, I guess. Not too difficult. You can also use type(obj) instead of obj.__class__. I thought of trying this, but didn't. It didn't seem likely to work, anyway. Is either of these preferred over the other in terms of API stability, and if so, why? obj.__class__ is a python thing, as is type(obj), and neither of those is changing in python 3.0, so I'd think both would be stable API wise :) However, the documentation of __class__ makes it clear you get the class back, while the documentation of the 'type' built in function does not...so I'd lean toward using __class__, myself. It also means you'll get an earlier error if you accidentally pass something that is not actually a class instance into your function. Thanks. That's very helpful. Regards, Faheem. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: inferring object class/table directly
def add_obj(session, obj):
Check if object primary key exists in db. If so,exit, else
add.
pid = obj.id
if session.query(obj.__class__).filter_by(id=pid).count():
print Patient object with id %s is already in db.%pid
exit
else:
session.save(obj)
session.commit()
Not too difficult. You can also use type(obj) instead of
obj.__class__.
Furthermore, if you really need to determine the object's class's
mapped table,
obj_table = obj.__class__._sa_class_manager.mapper.mapped_table
Of course, being an underscored thing, _sa_class_manager is not
something you should count on from version to version of sqlalchemy,
so keep that in consideration and don't use it anywhere you don't plan
to maintain.
Eric
On Dec 2, 2:24 pm, Faheem Mitha [EMAIL PROTECTED] wrote:
Hi,
If I have an ORM object, it is sometimes convenient to be able to infer
the class directly. Eg. consider this function.
def add_patient_obj(session, patient_obj):
Check if object primary key exists in db. If so,exit, else
add.
pid = patient_obj.id
#print session.query(Patient).filter_by(id=pid).count()
if session.query(Patient).filter_by(id=pid).count() 0:
print Patient object with id %s is already in db.%pid
exit
else:
session.save(patient_obj)
session.commit()
But I want a generic version. Since patient_obj knows what class is
belongs to, it should be possible not to have to state the class directly,
which here is Patient.
I have done the following, which works, but is hideous, horrible, ugly,
fragile hack. Can anyone suggest a better way of doing this?
Please CC me on any reply. Thanks in advance.
Regards, Faheem.
def add_obj(session, obj):
Check if object primary key exists in db. If so,exit, else
add.
c = str(type(obj)).split(')[1].split(.)[1]
s = q = session.query(+ c +)
exec(s)
pid = obj.id
if q.filter_by(id=pid).count() 0:
print Patient object with id %s is already in db.%pid
exit
else:
session.save(obj)
session.commit()
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[sqlalchemy] Re: inferring object class/table directly
On Dec 2, 2008, at 6:04 PM, Eric Ongerth wrote: def add_obj(session, obj): Check if object primary key exists in db. If so,exit, else add. pid = obj.id if session.query(obj.__class__).filter_by(id=pid).count(): print Patient object with id %s is already in db.%pid exit else: session.save(obj) session.commit() Not too difficult. You can also use type(obj) instead of obj.__class__. Furthermore, if you really need to determine the object's class's mapped table, obj_table = obj.__class__._sa_class_manager.mapper.mapped_table here's the API way: object_mapper(obj).mapped_table --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: inferring object class/table directly
[This message has also been posted.] Hi Eric, Thanks very much for the improvement. On Tue, 2 Dec 2008 15:04:34 -0800 (PST), Eric Ongerth [EMAIL PROTECTED] wrote: def add_obj(session, obj): Check if object primary key exists in db. If so,exit, else add. pid = obj.id if session.query(obj.__class__).filter_by(id=pid).count(): print Patient object with id %s is already in db.%pid exit else: session.save(obj) session.commit() Yes, I was looking for this, and printed out obj.__dict__ but didn't see it there. A dictionary of attributes is very useful in theory, but doesn't always seem to have all attributes. Is this documented anywhere? Not too difficult. You can also use type(obj) instead of obj.__class__. I thought of trying this, but didn't. It didn't seem likely to work, anyway. Is either of these preferred over the other in terms of API stability, and if so, why? Furthermore, if you really need to determine the object's class's mapped table, obj_table = obj.__class__._sa_class_manager.mapper.mapped_table Of course, being an underscored thing, _sa_class_manager is not something you should count on from version to version of sqlalchemy, so keep that in consideration and don't use it anywhere you don't plan to maintain. Not sure what the object class's mapped table is, but will look it up. Regards, Faheem. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: inferring object class/table directly
[This message has also been posted.] On Tue, 2 Dec 2008 18:25:19 -0500, Michael Bayer [EMAIL PROTECTED] wrote: On Dec 2, 2008, at 6:04 PM, Eric Ongerth wrote: [snip] Furthermore, if you really need to determine the object's class's mapped table, obj_table = obj.__class__._sa_class_manager.mapper.mapped_table here's the API way: object_mapper(obj).mapped_table Hi Michael, Thanks for the clarification. Regards, Faheem. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
