what kind of constraint has that problem, keep in mind there’s primary key
constraints, there’s a UNIQUE constraint if you say unique=True, etc.
need more info
dewey <de...@pathoz.com> wrote:
> I've added a naming convention to my metadata object (using declarative):
> customMetadata = MetaData(naming_convention=constraintNameConv) #
> schema='pay'
> Base = declarative_base(cls=DbBase, metadata=customMetadata,
> constructor=record_constructor)
>
> and now I'm getting this error when I try to generate the DB (new & empty):
> Naming convention including %(constraint_name)s token requires that
> constraint is explicitly named
>
> But all of my explicit constraints ARE NAMED as so:
> UniqueConstraint('sit_id', 'typ_id_ctr', 'typ_id_cont', 'version',
> name='sit_ctr_con_vers_uc')
>
> I'm assuming things like "unique", "index" in the declarative class (column
> construct) use the db field name?
>
> I'm wondering if this trick we used below:
> @event.listens_for(“before_parent_attach”, Column)
> Is related to the problem?
>
> Similarly, when I run:
> alembic upgrade head
>
> I'm getting errors like:
> Can't DROP 'cat_ctr_att_ibfk_4'; check that column/key exists
>
> And wondering if there is any connection between the two problems.
>
> Thanks for tips.
> D
>
>
>
> Friday, December 12, 2014 8:18:00 PM UTC-6, dewey wrote:
> Ok, I figured it out......parent (param 2) is the table obj, not the
> declarative class....which is fine
>
> btw: params for:
> @event.listens_for(“before_parent_attach”, Column)
> need to be reversed as so:
> @event.listens_for(Column, “before_parent_attach”)
>
> Thanks again for your help!! This tool rocks ;-)
> Dewey
>
> On Friday, December 12, 2014 7:48:16 PM UTC-6, dewey wrote:
> Mike,
> Thanks so much for the answer....I've watched a bunch of your
> video's....really good stuff.
>
> My prefix is derived from an attribute on the model-class.
> Is that what parent (2nd param to your event listener) will give me?
> Said a different way, how do I get a ref to the class in which the column is
> being (has been) defined.
>
> Thanks again.
> Dewey
>
> On Friday, December 12, 2014 6:05:06 PM UTC-6, Michael Bayer wrote:
>> On Dec 12, 2014, at 4:12 PM, dewey <de...@pathoz.com <>> wrote:
>>
>> after re-reading the docs, it seems I misunderstood the purpose of:
>>
>> __mapper_args__ = {'column_prefix': 'ste_'}
>>
>> that option is adding the prefix onto the Class att names, NOT onto the
>> actual DB column names in the table....
>>
>> I'm looking for a way to add a global prefix onto my DB column names.
>>
>> All suggestions appreciated.
>
>
> assuming this is a fixed prefix that is just set up once you would either
> make a function:
>
> from sqlalchemy import Column as _Column
>
> def Column(name, **kw):
> newname = “myprefix_%s” % name
> return _Column(newname, key=name, **kw)
>
> or if that is too simple, use the before_parent_attach event, which you’d
> have to stick on Column:
>
> @event.listens_for(“before_parent_attach”, Column)
> def attach(target, parent):
> target.name <http://target.name/> = “myprefix_%s” % target.name
> <http://target.name/>
> # target.key is OK here
>
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