Thanks!
On Friday, September 16, 2022 at 10:53:59 AM UTC-7 Mike Bayer wrote:
>
>
> On Fri, Sep 16, 2022, at 12:10 PM, mkmo...@gmail.com wrote:
>
> I use the following pattern in my REST APIs, building up the select,
> joins, where conditions, group bys, order bys, depending on the query
> parameters passed in by the user:
>
> selects = [Foo]
> joins = [(Bar, Foo.c.id == Bar.c.foo_id)]
> where_conditions = [Foo.c.id == request.args['pk']]
>
> if request.args.get('include_baz'):
> selects.append(Baz)
> joins.append((Baz, Bar.c.id == Baz.c.bar_id))
>
> What I would like to do is the following:
>
> sel = select(
> *selects
> ).join(
> *joins # doesn't work
> ).where(
> *where_conditions
> )
>
> This works for everything except for `join` and `outerjoin`. So I have to
> write it like this:
>
> sel = select(*selects)
> for table, condition in joins:
> sel = sel.join(table, condition)
> sel = se.where(*where_conditions)
>
> Is there some way to perform a join by passing an array of (table,
> conditions) so I can write the SQL without all of the `sel = sel. ` noise?
>
>
> if you have explicit join conditions like that, you might be able to
> make them into join objects:
>
> from sqlalchemy.orm import join
> sel.join(*[join(left, right, onclause) for right, onclause in conditions])
>
> IMO that's not really any better, or you can make a def like this:
>
> def join(stmt, conditions):
> for table, condition in conditions:
> stmt = stmt.join(table, condition)
> return stmt
>
> then you use it as:
>
> sel = join(sel, *joins)
>
> the form where we used to accept multiple join conditions inside of one
> join() method is part of legacy Query and is being removed. There are too
> many different argument forms for join() as it is for it to be appropriate
> for it to accept *args.
>
> personally I think "stmt = stmt.modifier(thing)" is the cleanest,
> including for the WHERE clause too.
>
>
>
> What I've been doing is using a function like the following:
>
> def collection_query(selects, joins, where_conditions, ...)
>
> But this has other problems and I would like to go back to raw sqlalchemy.
>
> Thanks and best regards,
>
> Matthew
>
>
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> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
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