add order_by() #26
add order_by() #26
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| await Product.objects.create(name="Dress", rating=3) | ||
| await Product.objects.create(name="Coat", rating=3, in_stock=True) | ||
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| coat = await Product.objects.order_by("name") |
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Let's use coat = await Product.objects.order_by("name").all() here.
| @@ -190,6 +197,10 @@ def select_related(self, related): | |||
| raise MultipleMatches() | |||
| return self.model_cls.from_row(rows[0], select_related=self._select_related) | |||
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| async def order_by(self, *args, **kwargs): | |||
| self._order_args = args | |||
| return await self.all(**kwargs) | |||
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We shouldn't have order_by run .all(...), so let's just do:
def order_by(self, *args):
self._order_args = argsThere was a problem hiding this comment.
Actually we should include order_args in the __init__, and create a new queryset in the same way we're currently doing in filter and select_related
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Hi @marco-silva0000, have you had a chance to review Tom's requested changes yet? If you don't have time, I can take over a submit an updated PR based on this. I'd be very interested in adding |
| @@ -48,6 +48,11 @@ def __new__( | |||
| return new_model | |||
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| def prepare_order_args(order_args): | |||
| from sqlalchemy.sql import text | |||
| return [text(arg) for arg in order_args] | |||
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After trying this out, it seems this isn't sufficient to use DESC on more complex datatypes such as datetimes.
May I suggest the more explicit implementation below? I tested this locally and it worked fine e.g. on .order_by('-created').
def prepare_order(model_cls, order):
prepared = []
for clause in order:
if clause.startswith("-"):
desc = True
col_name = clause.lstrip("-")
else:
desc = False
col_name = clause
col = model_cls.__table__.columns[col_name]
prepared.append(col.desc() if desc else col)
return preparedThere was a problem hiding this comment.
that war the initial idea, and the reason I've made a helper function in the first place. But my knowledge of sqlalchemy is low. Do you think any other datatypes may cause problems?
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No problem, I’m also just getting started with the SQLAlchemy core internals. :-)
The documentation highlights .desc() as the recommended way to sorting in descending order: https://docs.sqlalchemy.org/en/13/core/sqlelement.html#sqlalchemy.sql.expression.desc
So I think this should be good. Maybe @tomchristie has hints on how best this should be tested?
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sorry, I wanted to reply earlier but the message stayed as a draft. About the helper method that imports the 'text' class from alchemy, I made it like this because I was thinking I had to use different classes based on what fields were to be ordered. But in the end it worked with just text. |
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Any movement on this PR? |
implements the order by function
please review thoroughly as I'm not experienced with python3, async and sqiachemy
fixes #6