django - get first record for each day

Question

I have a model Sales with:

• Saler
• Product sold
• Date

I would like to get the first sale for each date and for each saler, how can I do that? Thanks

Answer 1

Not tested, but I would try (I assumed the field for the date of the sale is named sale_date, and is of type Datetime):

first_sale = Sales.objects.filter(saler=the_saler, sale_date__date=datetime.date(2021, 05, 19)).order_by('sale_date').first()

• filter will restrict the search to a given saler (the_saler), and to a given day (see the __date expression: https://docs.djangoproject.com/fr/3.1/ref/models/querysets/#date)
• order_by and first will give you the first of the day.

Answer 2

Considering the model Posted in the question, the Django ORM query will be:

first_sale = Sales.objects.order_by("Saler", "Date").distinct("Saler")