what does this error mean

[sylvoslee]

  File "D:\db\logic.py", line 8, in declare_logic
    Rule.sum(
  File "C:\lib\site-packages\logic_bank\logic_bank.py", line 104, in sum
    return Sum(derive, as_sum_of, where)
  File "C:\lib\site-packages\logic_bank\rule_type\sum.py", line 30, in __init__
    self._child_role_name = self.get_child_role_name(child_attrs=child_attrs)
  File "C:\\lib\site-packages\logic_bank\rule_type\aggregate.py", line 258, in get_child_role_name
    raise Exception(
Exception: Invalid 'as_sum_of' - not a reference to: Pur in Derive Pur.r_qty as Sum(Pur.qty Where None)

[valhuber]

Sorry, looks like a very poor error message.

It appears that the summed attribute is not in the child table.

For example, in the sample, see

Rule.sum(derive=models.Customer.Balance, # adjust iff AmountTotal or ShippedDate or CustomerID changes
as_sum_of=models.Order.AmountTotal,
where=lambda row: row.ShippedDate is None) # adjusts - *not* a sql select sum...

AmountTotal must be a valid attribute in Order (the child table being summed into Customer.Balance).

I would think that code completion would work here, so you get only valid choices.

If this is not enough, perhaps I would need to see your project.

[valhuber]

It may also be due to multiple relationships between 2 tables (Dept to Employees -- worksFor, onLoan). Fix in progress