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 = “myprefix_%s” % target.name
>> # target.key is OK here
>>
>>
>>
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