hello michael, friends,
On 07/11/2012 10:31 AM, alex bodnaru wrote:
>
> 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
>
sorry, not yet:
the relationship should also allow assignment like this:
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)
lang = relation('Lang', backref='pages',
primaryjoin=lang_code==Lang.lang_code, foreign_keys=[Lang.lang_code],
uselist=False)
the PageData.lang_code foreign key is being added in an event on before create.
before delaying creation of the foreign key, i could do like this:
p = PageData()
p.lang = Lang.get('en')
and p.lang_code got assigned. why isn't lang_code being assigned now anymore?
thanks in advance,
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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>>>>
>>>
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