Please provide a working and minimal mapping of your classes in question as
well as the SQL you wish to emit.
On Tue, Nov 10, 2020, at 12:07 PM, kris wrote:
>
> A little more detail..
>
> N = alias (T)
> node1 = session.query (N).filter(initial_node_filter).cte ('parents',
> recursive = True)
> parents = topnode.union (DBSession.query(N).filter (N.id == node1.c.parent_id)
> print session.query(parents).all()
> shows an array 'result'
> How to force it return class N or T
>
> On Tuesday, November 10, 2020 at 8:32:30 AM UTC-8 kris wrote:
>>
>> Initially I tried to remain solely in ORM constructs, I only broke down and
>> used the SQL expressions after hitting a wall.
>>
>> A little more specifically:
>> when I try:
>> session.query (part1).all ()
>> I receive an array of class 'sqlalchemy.util._collections.result' while I
>> was expecting an array of class T as the part1 cte actually creates a set of
>> T.
>>
>> Is there a way to let SA that result of the session.query(T).cte(...) is
>> actually a set of T?
>> Is there a way to convert 'result' tuples into class T?
>>
>> Thanks
>>
>>
>>
>>
>>
>>
>>
>>
>> On Tuesday, November 10, 2020 at 5:46:32 AM UTC-8 Mike Bayer wrote:
>>> __
>>> I would advise against using from_statement(). the Query object supports
>>> cte() and subqueries directly, see the example at
>>> https://docs.sqlalchemy.org/en/13/orm/query.html?highlight=query%20cte#sqlalchemy.orm.query.Query.cte
>>>
>>> alternatively if you are using 1.4 beta1 then you can use session.execute()
>>> directly using a select() object.
>>>
>>>
>>>
>>> On Tue, Nov 10, 2020, at 2:37 AM, kris wrote:
>>>>
>>>> I need to query over a table mapped to class T,
>>>> I usually use session.query (T), however I am using two cte's
>>>>
>>>> part0 = ... cte('part0')
>>>> part1 = ... cte('part1')
>>>> part2
>>>> = ... cte('aprt2')
>>>>
>>>> allparts = union (part1.select(), part2.select())
>>>>
>>>> session.query (allparts) .. returns row record but I need it to return
>>>> objects of type T?
>>>>
>>>> I have tried using q1 = session.query(T).from_statement (allnodes)
>>>> which appears to convert and create objects of T, However,
>>>> I cannot filter or order_by
>>>>
>>>> I have tried using the sql epxression level:
>>>> n = allparts.alias()
>>>> DBSession.query (T).from_statement (select ([n]).where (...).order_by
>>>> (...)).all()
>>>> or
>>>> DBSession.query(T).from_statement(DBSession.query
>>>> (n).filter(...).order_by(...).statement).
>>>>
>>>> but I get NoSuchColumnError: "Could not locate column in row for column
>>>> 'T.id'"
>>>>
>>>> Is there a way to let SA know how map the columns of the select expression
>>>> to an object?
>>>>
>>>> Thanks.
>>>>
>>>> --
>>>> SQLAlchemy -
>>>> The Python SQL Toolkit and Object Relational Mapper
>>>>
>>>> http://www.sqlalchemy.org/
>>>>
>>>> To post example code, please provide an MCVE: Minimal, Complete, and
>>>> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>>>> description.
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>>>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
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>
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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