while we are on the subject, i'd like to ask a question if i'm doing
it right or wrong.
i have created a class called Validation with a method called is_valid
and I have mixed it in my SQLAlchemy models. all of my models has an
attribute called validation that consists of model's attributes that
must be valid. it's like this:
class User(DeclarativeBase, Validation):
validation = {
'username': [formencode.validations.NotEmpty],
'email': [formencode.validations.NotEmpty,
formencode.validations.Email]
}
# model definition here..
and then in my controller i check if model_instance.is_valid() and
then add it to my db. if it's not valid, i render the previous page.
let me know if you guys have any recommendations.
On 27 Eylül, 21:56, Michael Bayer <[email protected]> wrote:
> On Sep 27, 2011, at 1:57 PM, Kirk Strauser wrote:
>
> > Does SA natively support (or is there a module on PyPI that supports)
> > client-side validation of SQLAlchemy objects? For example, I have this
> > declarative class:
>
> > class ImportedPayment(Base):
> > __tablename__ = 'importedpayment'
> > __table_args = {'schema': 'public'}
> > paymentid = Column(Integer, primary_key=True)
> > externalid = Column(String(16), nullable=False)
> > line = Column(Integer, nullable=False)
> > invoicestatus = Column(String(32), nullable=False)
> > quantity = Column(Numeric(scale=2), nullable=False)
> > rate = Column(Numeric(scale=2), nullable=False)
>
> > Is there an easy way to do this?
>
> OK so the aspect you're looking for here is to define those validations just
> once, this is easy enough through a recipe like this:
>
> def notnull(key):
> def validate(obj):
> if getattr(obj, key) is None:
> return "Object %s key %s is None" % (obj, key)
> else:
> return False
> return validate
>
> _validators = {}
>
> def get_validators(someobject):
> mapper = object_mapper(someobject)
> if mapper in _validators:
> return _validators[mapper]
> _validators[mapper] = v = []
> for prop in mapper.iterate_properties():
> if hasattr(prop, "columns"):
> col = prop.columns[0]
> if not col.nullable:
> v.append(notnull(prop.key))
> # ... ad nauesum, i.e.
> # if <something else about the column>:
> # v.append(<some other kind of validation function>)
> return v
>
> def validate(someobject):
> for validator in get_validators(someobject):
> msg = validator()
> if msg:
> log(msg)
> # etc., i.e.
> # alert_the_authorities()
>
> > If not, why?
>
> So the theme for today is "why does SQLA have recipes", basically when we can
> provide the core fragment of a feature but not a fully polished, documented,
> tested, packaged result, something that can just as easily be delivered as a
> small batch of customizable source code gets the job done pretty well, and
> would be better suited as a separate library if fully fleshed out.
>
> The above recipe lacks a lot of features one might want, such as customizable
> ways of defining the validation failure, behavior on the receipt of a failed
> validation, etc. A full blown "validation" library might use the idea
> above but expand upon it in a much bigger way. I've had other ad-hoc
> validation use cases that wouldn't work with the above structure, instead
> needing a slightly different structure, so having a small thing just as code
> for now is more flexible than a built in "feature" that only handles a small
> subset of use cases.
>
> > And if the answer to that is "because you haven't written it yet", would
> > anyone be interested in using it if I were to create such a thing?
>
> You might want to check around if similar things don't exist already, I did
> findhttp://pypi.python.org/pypi/SAValidation/andhttp://pypi.python.org/pypi/sqlalchemy_elixir_validations/for
> example, there might be features there that are of use. But by all means,
> produce a better validation library for SQLAlchemy, the more the merrier and
> I'd love to see more.
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