On Jan 17, 8:28 pm, pfwd <pfwdt...@googlemail.com> wrote:
> Hi am very new to Django/Python and I need some help with a model
> method
>
> I have two tables Linked by a foreign key and their forms are embedded
> in the admin interface.
> One table is called Quote and one table is called Task. The task table
> has a field called time_taken
> In the Quote list I want to display the total amount of time to under
> go all the tasks in each quote.
>
> This is what I'm doing and its just displaying (None) in the list
>
> class QuoteAdmin(admin.ModelAdmin):
> fieldset = [
> (None, {'fields': ['q_number']})
> ]
> inlines = [TaskInline]
>
> list_display = ('q_number', 'total_time','created_date')
>
> def total_time(self,queryset):
> task_objs = self.Task.objects.all()
>
> total_time = 'No time taken'
>
> for record in task_objs:
> total_time = total_time + record.time_taken
> return total_time
>
> I'm trying to get all the tasks for each quote by doing
> self.Task.objects.all() and then looping through them and adding the
> time_taken to the var total_time.
>
> I guess this syntax is just plain wrong or the method is not being
> called as its not showing any errors
> I have a javascript/PHP background and I would like to learn more
> Python
> - Please be kind :)
OK a few pointers.
* a custom list_display method takes parameters (self, obj), where obj
is the object being displayed in that row - here it's an instance of
Quote.
* 'self.Task' means nothing. You want to get the tasks related to the
Quote, which is in 'obj', so you use 'obj.task_set.all()'. With this,
your code would work as is.
* A nicer way of doing it would be to get the DB to sum the time_taken
values. This should work:
from django.db.models import Sum
return obj.task_set.aggregate(Sum('time_taken'))
['time_taken__sum']
(the square brackets at the end are needed because 'aggregate' returns
a dictionary, and we just want the value from there).
--
DR.
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