I'm using Django 4.0
, and Python 3.8
.
I have a product that has a modification date
, department name
and designation
.
I want to retrieve each product but, for products that have the same designation and the same department, I only want to retrieve the last entry.
Here is what i have now:
products = Product.objects.all().order_by('designation')
I tried sorting on the result and removing duplicate rows it worked for 10 rows but for 100 its dead
For the following data:
item: designation, date, department
- item_1, 01/01/1970, department_1
- item_2, 01/01/1970, department_2
- item_3, 01/01/1970, department_3
- item_1, 01/02/1970, department_1
I want:
- item_1, 01/02/1970, department_1
- item_2, 01/01/1970, department_2
- item_3, 01/01/1970, department_3
Do you have any advice please ?
edit: department is another model, and the relationship between product and department is Many to Many.
CodePudding user response:
If you're using a PostgreSQL database, use the distinct()
method on your QuerySet (link to Django documentation) to "eliminate duplicate rows from the query results".
In your case:
products = Product.objects.all().order_by('designation', 'department').distinct('designation', 'department')
If you're using another database, you can use distinct()
as well but without passing positional arguments (*fields
).