[sqlalchemy] updates using declarative extention
I'm trying to update one table. I'm using declarative extention for all db operations. I have successfully implemented updates using session after I first query the object and session keeps track of the changes subsequently. but I think for what I do, that prior query is a waste but prefer a straight update. Is this possible using declarative ext ? Thx. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: updates using declarative extention
Cool that worked. This is what I have done.
result =
session.query(Purchaser).filter(Purchaser.id==purchaser.id).update({'name':purchaser.name,'status':purchaser.status})
Thx Mike.
On Jun 15, 6:21 pm, Mike Conley mconl...@gmail.com wrote:
seehttp://www.sqlalchemy.org/docs/orm/query.html#sqlalchemy.orm.query.Qu...
We use session.query(..).update(..,synchronize_session=False) for
updates where we are sure about the criteria and session state. This
generates an update statement without any selects.
--
Mike Conley
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[sqlalchemy] mapper error, and db object cannot be incremented
I'm new to SQLAlchemy. I wrote a method that retrieves a record,
update the object after incrementing it by 1, and return that record
object to the caller (pyramid view). Following is the test function. I
get following errors :
1) when I call this method multiple times, I get an error that say
ArgumentError: Class 'class 'cas.models.Models'' 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.
As a resolution i called 'clear_mappers()' before invoking mapper.
2) I cant seem to increment the attribute of an object in orm session.
My understanding is that once a record is retrieved in an ORM session,
Session object keeps track of any changes to the record object and
updates the record when session.flush() is invoked.
But I get error TypeError: unsupported operand type(s) for +:
'instancemethod' and 'int'
Can someone please explain to me what I'm doing wrong ?
class Models(object):pass
def countAndIncrement():
metadata = MetaData('sqlite:///CAS.db')
model_table = Table('models',
metadata,
Column('id',Integer,primary_key=True),
Column('name',String(40)),
Column('value',Integer)
)
clear_mappers()
mapper(Models,model_table) # already a
primary mapper defined error (when I call this function multiple times
Session = sessionmaker()
session = Session()
model = session.query(Models).filter(Models.id==1)
model.value = model.value + 1 #
increment error
session.flush()
session.close()
return model
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[sqlalchemy] Re: mapper error, and db object cannot be incremented
Thank you so much Michael. By the way SQLAlchemy and Mako template are
so cool. Thank you so much for all your efforts.
Liju.
On Jun 14, 9:38 am, Michael Bayer mike...@zzzcomputing.com wrote:
You're best starting with the declarative usage patterns described in the ORM
tutorial athttp://www.sqlalchemy.org/docs/orm/tutorial.html, starting
withhttp://www.sqlalchemy.org/docs/orm/tutorial.html#creating-table-class
I would declare the class + table + mapping at once, to eliminate any
confusion regarding mapping, which is not a per-usage operation; it is a
permanent operation applied to a model class only once. The mapper() +
Table pattern is not as easy to use and it's being de-emphasized in the
documentation.
The second error implies your class has a method called value() on it which
is conflicting with the mapped attribute of .value.
On Jun 14, 2011, at 12:22 PM, Liju wrote:
I'm new to SQLAlchemy. I wrote a method that retrieves a record,
update the object after incrementing it by 1, and return that record
object to the caller (pyramid view). Following is the test function. I
get following errors :
1) when I call this method multiple times, I get an error that say
ArgumentError: Class 'class 'cas.models.Models'' 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.
As a resolution i called 'clear_mappers()' before invoking mapper.
2) I cant seem to increment the attribute of an object in orm session.
My understanding is that once a record is retrieved in an ORM session,
Session object keeps track of any changes to the record object and
updates the record when session.flush() is invoked.
But I get error TypeError: unsupported operand type(s) for +:
'instancemethod' and 'int'
Can someone please explain to me what I'm doing wrong ?
class Models(object):pass
def countAndIncrement():
metadata = MetaData('sqlite:///CAS.db')
model_table = Table('models',
metadata,
Column('id',Integer,primary_key=True),
Column('name',String(40)),
Column('value',Integer)
)
clear_mappers()
mapper(Models,model_table) # already a
primary mapper defined error (when I call this function multiple times
Session = sessionmaker()
session = Session()
model = session.query(Models).filter(Models.id==1)
model.value = model.value + 1 #
increment error
session.flush()
session.close()
return model
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[sqlalchemy] SQLAlchemy best practise
I'm new to SQLAlchemy and loving it. But reading all documentation online makes me wonder if there are any best practice documentation for sqlalchemy out there ? -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
