Michael thanks for the help, this is how I was able to get it working.
Probably isn't the most efficient, but it works, I couldn't implement it
the way you proposed because I still need to be able to do "a_row = b_row.A"
---------
sql_b = select([b_table, sql_a.c.name], b_table.c.a_id =
sql_a.c.id).alias('b_query')
mapper(b, sql_b, properties = {
'A' : relation(A, lazy=False, primaryjoin=(sql_a.c.id==sql_b.c.a_id))})
mapper(C, c_table, properties = {
'Bs' : relation(B, backref='C', cascade='all, delete-orphan',
order_by=[sql_b.c.name, sql_c.c.value1,
sql_c.c.value2]),
})
Michael Bayer wrote:
> On Dec 5, 2007, at 1:56 PM, David Gardner wrote:
>
>
>> I have three tables a(a query of a really), b, c
>>
>> a has a 1-many relationship with b
>> c has a 1-many relationship with b
>>
>> What I would like to do is in my mapper for table c, is sort the order
>> of rows from b by a.name.
>> I don't know how to do this or if it is possible. What I have looks
>> like:
>>
>> sql_a = select([table_a], table_a.c.col1='some
>> value').alias('a_query')
>>
>> mapper(B, b_table, properties = {
>> 'A' : relation(sql_a, lazy=False,
>> primaryjoin=(sql_a.c.id==table_b.c.a_id))})
>>
>> mapper(C, c_table, properties = {
>> 'Bs' : relation(B, backref='C', cascade='all, delete-orphan',
>> order_by=[C.A.name, c_table.c.value1,
>> c_table.c.value2]),
>> })
>>
>> This gets me an "AttributeError: 'InstrumentedAttribute' object has no
>> attribute 'name'"
>>
>
> this error is becuase C.A is not a gateway to the columns on the "A"
> mapper.
>
>
>> I have also tried:
>> order_by=[A.name
>> and
>> order_by=[sql_a.c.name
>>
>> both get me this: ProgrammingError: (ProgrammingError) missing
>> FROM-clause entry for table "sql_a.name"
>>
>
> this error is because the relation from C->B has no relationship to
> "A"s table at all, and it is not used in the generated query. to have
> "A"s table be a part of it in all cases, youd have to map A's column
> onto B's mapper, which is fairly messy:
>
> mapper(B, select([b_table, a.c.name], b_table.c.a_id==a.c.id))
>
> you can try creating this mapper as a "non-primary" mapper and using
> it for just the C->B relation:
>
> s = select([b_table, a.c.name], b_table.c.a_id==a.c.id)
> mapper(C, ctable, properties={
> 'bs':relation(mapper(B, s, non_primary=True), order_by=[s.c.name])
> })
>
> I havent tried the above myself so see if it works for you.
>
> >
>
>
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