TypeError: unsupported type for timedelta microseconds component: InstrumentedAttribute

TypeError: unsupported type for timedelta microseconds component: InstrumentedAttribute

Problem Description:

i am also getting error while doing this task.

Models.py

CloudImageMaster

created_tmstmp = Column(DateTime(), default = datetime.now(timezone.utc))

ClientMaster

ttl = Column(BigInteger, nullable=False)

QUERY:-

db.query(CloudImageMaster).join(ClientMaster).filter(
    (
    CloudImageMaster.created_tmstmp + timedelta(microseconds=ClientMaster.ttl)
    ) < today
).all()

ERROR MESSAGE :-

TypeError: unsupported type for timedelta microseconds component: InstrumentedAttribute

I tried above. It should work as per the code. What i am doing wrong in this.

Solution – 1

Given a filter expression like MyMode.attr == something, the left hand side (LHS) can be thought of as belonging to the database side, the right hand side (RHS) as belonging to the application. What this means is that the RHS must be expressed in what SQLAlchemy regards as database constructs (ORM entities, tables, columns, database functions) while the LHS is expressed as normal Python code.

This means that we can’t subtract a timedelta (a Python construct) from a Datetime column (a database construct); we have to convert the timedelta to a database construct – a PostgreSQL interval. We can do this by using the make_interval function, dividing ttl by 1000 as make_interval does not accept a microsecond argument.

from sqlalchemy import func

db.query(CloudImageMaster)
  .join(ClientMaster)
  .filter(
      (
          CloudImageMaster.created_tmstmp
          + func.make_interval(0, 0, 0, 0, 0, 0, ClientMaster.ttl /1000)
      ) < today
  ).all()