[sqlalchemy] Re: Handling unique constraints
Matt Haggard wrote:
I'm using SQLAlchemy with Pylons and am having trouble validating
data. I have an App object mapped to a table with a unique constraint
on App.number.
Here's some code:
q = Session.query(App)
if app_id:
q = q.filter_by(id=app_id).first()
if q:
c.app = q
number = request.params.get('number')
notes = request.params.get('notes')
if appmodel and number:
try:
q.number = number
q.notes = notes
Session.save(q)
Session.commit()
c.message = 'Record updated'
except:
# restore pre-form data ?? how??
c.message = 'Error updating record'
return render('index.mtl')
else:
return self.index()
My questions are:
1) When I do the try statement, the value of q.number changes to
whatever the user passed in via the form -- even if it's invalid, so
that when I render the page, the invalid value is used. How do I
reset the object to have the values it had before I did the try? Do I
have to get it afresh from the db?
try something like session.refresh( obj) or similar
2) How do I let the user know which value caused the record not to
update? What information does SQLAlchemy provide back that I can use
to say: You're number must be unique... and such-and-such must be
greater than 0, etc..?
mmh, do not mistake DB-constraints with validation-rules.
the only sensible info u can get here is that the record is not unique
(check what sort of exception that throws), but any further interpretation -
why, what, where - is up to you - u have to know what field u have just
set/changed, etc.
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[sqlalchemy] Re: Emptying out the session of new objects
On Jan 4, 2008, at 9:46 PM, Dave Harrison wrote: Hey Mike, Below is a minimal test case that always produces the below failure for me under 0.4.2 but not under 0.4.1, OK, its actually something that was buggy in 0.4.1 but didnt produce a symptom, give r4003 a try which fixes this issue...0.4.2a is today --~--~-~--~~~---~--~~ 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] Schema display
Hi Guys, I was wondering where the function create_schema_graph has gone, or what it has changed to. Any assistance would be appreciated. Let me know, Morgan --~--~-~--~~~---~--~~ 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: Emptying out the session of new objects
On Sunday 06 January 2008 05:30:04 Michael Bayer wrote: On Jan 4, 2008, at 9:46 PM, Dave Harrison wrote: Hey Mike, Below is a minimal test case that always produces the below failure for me under 0.4.2 but not under 0.4.1, OK, its actually something that was buggy in 0.4.1 but didnt produce a symptom, give r4003 a try which fixes this issue...0.4.2a is today Hi Mike, That seems to have solved it for me. Thanks for the quick turn around, SQLAlchemy and the team continue to amaze ! :-) Cheers Dave --~--~-~--~~~---~--~~ 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] Polymorphic mappers on boolean types
Hey all,
More fun with inheritance and mappers. In the following situation
where the polymorphic type is a Boolean, the mapper for the object
that matches on False incorrectly returns the parent object.
Cheers
Dave
--
-- testapi.py
--
from sqlalchemy import *
from sqlalchemy.orm import *
session = scoped_session(
sessionmaker(autoflush=False, transactional=True)
)
mapper = session.mapper
metadata = MetaData()
ANIMAL_TYPE_DOG = True
ANIMAL_TYPE_CAT = False
VET_TYPE_CITY = 1
VET_TYPE_COUNTRY = 2
animalTable = Table(
'animal',
metadata,
Column('id', Integer, primary_key=True),
Column('type', Boolean, nullable=False),
Column('name', String(100), nullable=False),
Column('vet_id', Integer, ForeignKey('vet.id')),
)
vetTable = Table(
'vet',
metadata,
Column('id', Integer, primary_key=True),
Column('address', String(100), nullable=False),
Column('kennel', Boolean, nullable=False),
)
class _Animal(object):
pass
class Cat(_Animal):
pass
class Dog(_Animal):
pass
class Vet(object):
pass
vetMapper = mapper(
Vet,
vetTable,
properties = {
animals: relation(
_Animal,
backref=backref(vet, uselist=False),
cascade=all, delete-orphan
),
}
)
animalMapper = mapper(
_Animal,
animalTable,
polymorphic_on=animalTable.c.type,
)
mapper(
Dog,
inherits=animalMapper,
polymorphic_identity=ANIMAL_TYPE_DOG,
)
mapper(
Cat,
inherits=animalMapper,
polymorphic_identity=ANIMAL_TYPE_CAT,
)
def connect(uri):
engine = create_engine(uri, strategy=threadlocal)
metadata.bind = engine
return engine
def create():
metadata.create_all()
def drop():
metadata.drop_all()
--
-- test.py
--
import sys
import testapi as db
DB = sqlite:///memory
db.connect(DB)
db.create()
v = db.Vet()
v.address = 12 Foo St
v.kennel = True
c1 = db.Cat()
c1.name = muffin
c2 = db.Cat()
c2.name = bagel
d1 = db.Dog()
d1.name = rex
d2 = db.Dog()
d2.name = bill
db.session.flush()
db.session.clear()
for d in db.Query(db.Dog).all():
v.animals.append(d)
for c in db.Query(db.Cat).all():
v.animals.append(c)
db.session.flush()
db.session.clear()
v = db.Query(db.Vet).first()
for a in v.animals:
print a
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[sqlalchemy] Re: Handling unique constraints
Matt,
Take a look at the formencode module, it will simplify what you are
trying to do here - handles all your parameter validation, form
filling, and telling the user X,Y,Z are wrong etc.
http://wiki.pylonshq.com/display/pylonsdocs/Form+Handling
and formencode docs
http://www.formencode.org/
On Jan 5, 12:13 am, [EMAIL PROTECTED] wrote:
Matt Haggard wrote:
I'm using SQLAlchemy with Pylons and am having trouble validating
data. I have an App object mapped to a table with a unique constraint
on App.number.
Here's some code:
q = Session.query(App)
if app_id:
q = q.filter_by(id=app_id).first()
if q:
c.app = q
number = request.params.get('number')
notes = request.params.get('notes')
if appmodel and number:
try:
q.number = number
q.notes = notes
Session.save(q)
Session.commit()
c.message = 'Record updated'
except:
# restore pre-form data ?? how??
c.message = 'Error updating record'
return render('index.mtl')
else:
return self.index()
My questions are:
1) When I do the try statement, the value of q.number changes to
whatever the user passed in via the form -- even if it's invalid, so
that when I render the page, the invalid value is used. How do I
reset the object to have the values it had before I did the try? Do I
have to get it afresh from the db?
try something like session.refresh( obj) or similar
2) How do I let the user know which value caused the record not to
update? What information does SQLAlchemy provide back that I can use
to say: You're number must be unique... and such-and-such must be
greater than 0, etc..?
mmh, do not mistake DB-constraints with validation-rules.
the only sensible info u can get here is that the record is not unique
(check what sort of exception that throws), but any further interpretation -
why, what, where - is up to you - u have to know what field u have just
set/changed, etc.
--~--~-~--~~~---~--~~
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To unsubscribe from this group, send email to [EMAIL PROTECTED]
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