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
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