[Fixed]-Why isn't there a simple group_by in Django?

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1👍

✅

This isn’t what SQL group by is — in SQL you would have to choose which of Bob or Sara would be returned for the Sales – 12/12 row, you couldn’t have both. I’d do this processing in Python, there’s no real SQL for what you want.

For instance, keep a dictionary of (department name, date) tuples and a list of names as values:

from collections import defaultdict

table = defaultdict(list)

for department, date, name in Person.objects.values_list(
        'department__name', 'start_date', 'name'):
    table[(department, date)].append(name)
👤RemcoGerlich

0👍

The way you can do your group_by in django is using values and aggregate.

For example, you can achieve the result you want by making it like this:

Person.objects.all().values('department__name', 'start_date').annotate(Count('start_date'))

However I believe you can not get all the names in a single string, and AFAIK you also could not do it in a simple GROUP BY on mysql, for example.

EDIT: just now I’ve understood that you want to group_by two values, so you would do something like:

    Person.objects.all().values('department__name', 'start_date')\
        .annotate(Count('start_date'))\
        .annotate(Count('department__name'))\
        .values_list('department__name','start_date')
👤jorgemdnt

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