hello michael,
now it works. i also had to add uselist=False.
i tried it the longest way possible, by adding a Pool first_connect listener,
but this was not really needed. just the uselist.
thanks a lot,
alex
On 07/09/2012 04:25 PM, Michael Bayer wrote:
>
> On Jul 9, 2012, at 4:48 AM, alex bodnaru wrote:
>
>>
>> hello michael, friends,
>>
>> after successfuly fixing the ddl by the append_constraint event, the
>> relations
>> that needed the said foreign keys remained orphan, asking for a foreign_keys
>> argument and failing to load the remote table:
>>
>> class Lang(DeclarativeBase):
>> lang_code = Column(String(20), primary_key=True)
>> lang_name = Column(String(20))
>>
>> class PageData(DeclarativeBase):
>> lang_code = Column(String(20), primary_key=True) # this foreign key is
>> being
>> successfully appended on before_create.
>> lang = relation('Lang', backref='pages',
>> primaryjoin=lang_code==Lang.lang_code) #this relationship won't work, since
>> at
>> the moment the class is being made, the foreign key is not there yet.
>>
>> the foreign_keys=Lang.lang_code arg does calm the exception, but doesn't do
>> the
>> work.
>> could i add the relationship to the mapper on the same event?
>
> I would think "foreign_keys" should fix the problem totally, what do you mean
> "doesn't do the work"? I'd have to work up a test case, can you just throw
> these two classes, the event, and some imports into a file for me ? I can
> just run it.
>
well, almost totally ;)
it also needed uselist=False.
>
>>
>> thank in advance,
>> alex
>>
>> On 07/07/2012 05:13 PM, Michael Bayer wrote:
>>> sure engine and connection have .dialect.name. Foreign key constraints
>>> don't matter on SQLite unless you've actually enabled them, which is rare.
>>> I'd still use an event though so at least the behavior is transparent.
>>>
>>> @event.listens_for(my_table, "before_create")
>>> def add_fk(table, conn, **kw):
>>> if conn.dialect.name != 'mssql':
>>> table.append_constraint(ForeignKeyConstraint(...))
>>>
>>> tricky though to modify the table metadata within a "create" event in the
>>> case that the table is created multiple times in an app. you can put a
>>> flag in table.info, like "table.info['added_the_fk'] = True", to keep track
>>> of things.
>>>
>>>
>>>
>>> On Jul 7, 2012, at 12:59 AM, alex bodnaru wrote:
>>>
>>>>
>>>> hello mike and thanks for your answer.
>>>>
>>>> no problem with ForeignKeyConstraint, but wouldn't AddConstraint go the
>>>> alter
>>>> way? in this case, it will be ignored by the sqlite dialect.
>>>>
>>>> what i was looking for was more like:
>>>>
>>>> from sqlalchemy... import get_dialect
>>>>
>>>> ....
>>>> fk_parms = dict(.....)
>>>> if get_dialect() != 'mssql':
>>>> fk_parms.update(onupdate='restrict')
>>>> fk = ForeignKey(**fk_parms)
>>>>
>>>> would the dialect be accessible from the engine, metadata etc?
>>>>
>>>> thanks in advance,
>>>> alex
>>>>
>>>>
>>>> On 07/06/2012 11:39 PM, Michael Bayer wrote:
>>>>> you'd use ForeignKeyConstraint along with the AddConstraint directive,
>>>>> and limit it per-dialect using create/drop events as documented at
>>>>> http://docs.sqlalchemy.org/en/rel_0_7/core/schema.html#controlling-ddl-sequences
>>>>> .
>>>>>
>>>>>
>>>>> On Jul 6, 2012, at 1:30 PM, alex bodnaru wrote:
>>>>>
>>>>>>
>>>>>> hello friends,
>>>>>>
>>>>>> i need to define a foreign key differently for different dialects:
>>>>>> ondelete='restrict' for most engines, but nothing (implied and not
>>>>>> recognized)
>>>>>> for mssql.
>>>>>>
>>>>>> could you help?
>>>>>>
>>>>>> thanks in advance,
>>>>>> alex
>>>>>>
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>>>>>
>>>>
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