I recommend this book - and the answer to your question is in chapter 8. http://www.amazon.com/Practical-Django-Projects-Pratical/dp/1590599969
go ahead and get this one too http://www.amazon.com/Python-Essential-Reference-David-Beazley/dp/0672329786/ref=pd_sim_b_4 and read http://diveintopython.org/ as well :) On Jan 18, 12:08 am, pfwd <pfwdt...@googlemail.com> wrote: > Thanks fantastic thank you > I was also able to do: > result = obj.task_set.aggregate(Count('id'))['id__count'] > to get the a count of the tasks for quote > > I don't suppose you know any good books regarding Python/Django that I > could buy to help me learn the syntax better? > > Many thanks > > On Jan 17, 10:15 pm, Daniel Roseman <dan...@roseman.org.uk> wrote: > > > 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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