Sum fields in sqlAlchemy

Question

I recently upgraded to the latest version of sqlalchemy, and some of my code no longer works. I find it difficult to find how to fix this and use my hand.

Previously, the request appeared as follows.

self.db.query(Drive).filter(Drive.package_id==package.package_id)\ .filter(Drive.wipe_end!=None).sum(Drive.wipe_end - Drive.wipe_start) 

this worked before getting the sum of some durations, but now I get the following error:

 'Query' object has no attribute 'sum' 

Any googling I receive receives information that is several years old.

Answer 1

I believe you need the sum () function in the "func" package:

 from sqlalchemy import func cursor = self.db.query(func.sum(Drive.wipe_end - Drive.wipe_start)).filter(Drive.package_id==package.package_id).filter(Drive.wipe_end!=None) total = cursor.scalar() 

Answer 2

In SQLAlchemy 1.1.13 (released August 3, 2017), the syntax for using sum() is this:

 from sqlalchemy import func from apps.mystuff.models import MyModel some_value = "hello" result = MyModel.query.with_entities( func.sum(MyModel.MyColumn).label("mySum") ).filter_by( MyValue=some_value ).first() # Depending on the column datatype, it either int: print(result.mySum) # Or if the data is decimal/float: print(float(result.mySum)) 

The main difference compared to the original answer is that instead of:
query(func.sum())

The syntax has changed before this since version 0.6.5:
query.with_entities(func.sum())

http://docs.sqlalchemy.org/en/latest/orm/query.html#sqlalchemy.orm.query.Query.with_entities