Sqlalchey query date filter with string format

Question

I have sqldb where date is encoded as string. By using of sqlalchemy I need to implement query, where date is used as a filter (date within specific range). I tried to define hybrid method, but it seems, that datetime.strptime cannot be used here ("TypeError: strptime() argument 1 must be str, not InstrumentedAttribute")

Do you have any idea (maybe different approach than hybrid method), how to make it working?

Sample code:

class Sample(db.Model):
__tablename__ = "sample"

id = db.Column(db.Integer, primary_key=True)
date = db.Column(db.String(32))

@hybrid_property
def date2(self):
    return datetime.datetime.strptime(self.date, "%Y-%m-%d")

@date2.expression
def date2(cls):
    return datetime.datetime.strptime(cls.date, "%Y-%m-%d")

...

date_min = datetime.datetime(2020, 1, 1)
date_max = datetime.datetime(2020, 3, 31)
out = Sample.query.filter_by(date2 > date_min, date2 < date_max).all()

r-m-n · Accepted Answer · 2020-03-18 06:20:28Z

1

You can use STR_TO_DATE function in MySQL:

from sqlalchemy import func

@date2.expression
def date2(cls):
    return func.str_to_date(cls.date, "%Y-%m-%d")

answered Mar 18, 2020 at 6:20

r-m-n

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