[sqlalchemy] Re: relation does not honor order_by attribute

[Gaetan de Menten]

On Wed, Oct 14, 2009 at 08:34, robert rottermann rob...@redcor.ch wrote:

 I am using a one to many relation, and would like the result to be ordered by 
 a
 field of the child table. however no order by statement is executed when I
 access the related property of the parent object.

 this is my declaration:

 mitarbeiter_table = Table('mitarbeiter', Base2.metadata, autoload=True)
 class mitarbeiterCL(Base2):
    __table__ = mitarbeiter_table

 abwesenheit_table = Table('abwesenheit', Base2.metadata, autoload=True)
 class abwesenheitCL(Base2):
    __table__ = abwesenheit_table

    mitarbeiter = relation(
        mitarbeiterCL,
        uselist=False,
        backref='abwesenheiten',
        order_by =  abwesenheit_table.c.datumvon,
    )

The problem is that you are specifying the order_by on the wrong side
of the relationship (ie on the ManyToOne side). You need to place the
order_by on the OneToMany side, and in your precise example, that
means, on the backref.

mitarbeiter = relation(
mitarbeiterCL,
uselist=False,
backref=backref('abwesenheiten', order_by=abwesenheit_table.c.datumvon)
)

-- 
Gaëtan de Menten
http://openhex.org

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[sqlalchemy] Re: relation does not honor order_by attribute

[robert rottermann]

thanks
robert
Gaetan de Menten schrieb:
 On Wed, Oct 14, 2009 at 08:34, robert rottermann rob...@redcor.ch wrote:
 
 I am using a one to many relation, and would like the result to be ordered 
 by a
 field of the child table. however no order by statement is executed when I
 access the related property of the parent object.

 this is my declaration:

 mitarbeiter_table = Table('mitarbeiter', Base2.metadata, autoload=True)
 class mitarbeiterCL(Base2):
__table__ = mitarbeiter_table

 abwesenheit_table = Table('abwesenheit', Base2.metadata, autoload=True)
 class abwesenheitCL(Base2):
__table__ = abwesenheit_table

mitarbeiter = relation(
mitarbeiterCL,
uselist=False,
backref='abwesenheiten',
order_by =  abwesenheit_table.c.datumvon,
)
 
 The problem is that you are specifying the order_by on the wrong side
 of the relationship (ie on the ManyToOne side). You need to place the
 order_by on the OneToMany side, and in your precise example, that
 means, on the backref.
 
 mitarbeiter = relation(
 mitarbeiterCL,
 uselist=False,
 backref=backref('abwesenheiten', 
 order_by=abwesenheit_table.c.datumvon)
 )
 


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