How to filter a query by columns only if another condition is met

user_8165283 0
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I have a query:

query = Usage.query.filter_by(site_id=self.site_id, invoice_num=self.invoice_num, supply_charge=self.supply_charge)

And want to filter by dates:

.filter(Usage.start_date>four_months_ago)

only if the row getting filtered has the same value:

if subtotal == self.subtotal

Is there a better way of doing this than making a for loop? It seems very inefficient.

for row in query.all():
    if self.start_date > four_months_ago:
        if row.subtotal != self.subtotal:
            del row
sqlalchemy sql python
1 Answers

Condition

(subtotal == self.subtotal) & (Usage.start_date > four_months_ago)

looks like

WHERE start_date > 'val1' AND subtotal = val2

otherwise, OR subtotal != val2. You can try to use or_ + and_. Just an example:

subtotal = 1
for user in Usage.query.filter(
    Usage.site_id == 2,
    Usage.invoice_num == 3,
    Usage.supply_charge == 4,
    or_(
        and_(Usage.start_date > for_month_ago, Usage.subtotal == subtotal),
        Usage.subtotal != subtotal,
    )
):
    print(user)
user_49296460
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