On 5/20/10 8:04 AM, Ed Leafe wrote:
> On May 20, 2010, at 10:19 AM, Carey Gagnon wrote:
>
>> The brick wall I hit is this:
>>
>> I have a database with different customers, projects, and tasks, with start
>> times and end times. I have created a virtual field to get the duration of
>> those tasks. Works great to here.
>>
>> The brick wall??
>>
>> Now I want to take that duration virtual field and create another virtual
>> field that will calculate the total time for the project.
>
> I'm not sure that another virtual field is the best solution, unless it
> is defined as part of the project bizobj. Is that what you're doing? It would
> be pretty meaningless as part of the tasks bizobj.
>
> If the virtual field is defined in the project bizobj, it is
> straightforward to calculate the sum of the child values for a given project.
> Paul has done much more work on this, so I'm hoping he can give you a better
> example than I could come up with.
If I understand correctly, you have a Projects bizobj that has a Tasks bizobj
as a
child. The Tasks bizobj has a virtual field that figures out the time_spent on
each
row by deriving it from time_start and time_finished. That is working.
Now, you want a VirtualField in the Projects bizobj that totals all the
Tasks.Record.time_spent values. There are different ways to accomplish this but
I
tend to do:
from decimal import Decimal
class Projects(dabo.biz.dBizobj):
def initProperties(self):
self.bizTasks = BizTasks(self.Application.dbConnection)
self.addChild(self.bizTasks)
self.VirtualFields["project_time_spent"] = self.getProjectTimeSpent
...
def getProjectTimeSpent():
tasks = self.bizTasks
ds = tasks.getDataSet(flds=("time_spent","))
if not ds:
return Decimal("0")
return sum([r["time_spent"] for r in ds])
Paul
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