On 9/8/15 4:13 AM, Jacob Magnusson wrote:
Michael,
Is there any chance we might see support for /with_labels/ in this use
case? Even though my "solution" works, it's somewhat of an annoyance
with all these warnings being spit out:
/SAWarning: Column 'id' on table <sqlalchemy.sql.selectable.Select
at 0x110cd5d30; Select object> being replaced by Column('id',
Integer(), table=<Select object>, primary_key=True,
nullable=False), which has the same key. Consider use_labels for
select() statements./
It's not clear how with_labels() can be made to work with this without a
lot of re-thinking of many of the internal aspects of the Query and
related objects. OTOH, the Bundle object is fully customizable and as
I recommended, a custom approach that applies labels to Column objects
as they are passed and translates back as needed on the result side is
feasible right now; I'd rather add a labeling/nesting feature to Bundle
itself based on the discoveries gained by working with that approach as
a recipe.
On Friday, April 10, 2015 at 12:19:31 AM UTC+2, Michael Bayer wrote:
On 4/9/15 1:50 PM, Jacob Magnusson wrote:
I have this case with a bundle that looks something like this:
|primate_bundle = Bundle( 'primate', Primate.name,
Bundle('wooden_tool', *[ WoodenTool.id, WoodenTool.name,
WoodenToolCategory.name.label('category'), ]),
Bundle('solid_tool', *[ SolidTool.id, SolidTool.name,
SolidToolCategory.name.label('category'), ]) ) |
Then I query it like this:
|session.query(primate_bundle) .select_from(Primate)
.join(WoodenTool, Primate.main_tool) .join(WoodenToolCategory,
WoodenTool.category_id == WoodenToolCategory.id) .join(SolidTool,
Primate.secondary_tool) .join(SolidToolCategory,
SolidTool.category_id == SolidToolCategory.id) .all() |
However, since the label for category name is the same within
both sub-bundles it will throw |Ambiguous column name| (because
the compiled SQL labels will be exactly the same). Adding
|.with_labels()| doesn’t fix it. Full traceback can be seen by
running the included examples. Commenting out one of the
|.label()| lines in the example makes it runnable. Do you guys
have a clean solution to support this use case? I really like
this feature of creating your own custom made results so it would
be a shame to not be able to do this.
OK well here's one hacky way, that we could better accommodate by
adding a "key" parameter to label(), this is sort of like your
other approach: ay = A.y.label(None) ay.key = 'foobar' bp =
B.p.label(None) bp.key = 'foobar' ab = Bundle( 'ab',
Bundle('a', *[ A.id, A.x, ay, ]),
Bundle('b', *[ B.id, B.q, bp, ]) ) The
other way is to provide create_row_processor() as we describe
here:
http://docs.sqlalchemy.org/en/rel_0_9/orm/loading_columns.html?highlight=bundle#column-bundles
<http://docs.sqlalchemy.org/en/rel_0_9/orm/loading_columns.html?highlight=bundle#column-bundles>.
That way you could just make this work any way you wanted: from
sqlalchemy import util class LabelBundle(Bundle): def
__init__(self, *arg, **kw): self.extra_labels =
kw.pop('extra_labels', {}) super(LabelBundle,
self).__init__(*arg, **kw) def create_row_processor(self,
query, procs, labels): # or use a NamedTuple here
keyed_tuple = util.lightweight_named_tuple( 'result',
[self.extra_labels.get(l, l) for l in labels]) def
proc(row): return keyed_tuple([proc(row) for proc in
procs]) return proc ab = LabelBundle( 'ab',
LabelBundle( 'a', extra_labels={'y': 'foobar'},
*[A.id, A.x, A.y]), LabelBundle( 'b',
extra_labels={'p': 'foobar'}, *[B.id, B.q, B.p]) )
Tested on SQLAlchemy 1.0.0b5 and 0.9.9. Python 3.
Thank you so much for any potential help you can give me on this.
I’ve followed the source code for |Bundle| but I can’t think of a
clean way to this…
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