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Is it possible to replicate this kind of specific sql ordering in the django ORM:
order by
(case
when id = 5 then 1
when id = 2 then 2
when id = 3 then 3
when id = 1 then 4
when id = 4 then 5
end) asc
?
874
Django has order_by method to sort the queryset in ascending and descending order. You can order the queryset on any field. In the Django model, there is one autogenerated 'id' field. You can use any of the fields (id name, mobile or name) to sort the queryset.
In my last Django project, we had a set of helper functions that we used a lot. The most used was helpers. first, which takes a query set and returns the first element, or None if the query set was empty. Instead of writing this: try: object = MyModel.objects.get(key=value) except model.DoesNotExist: object = None.
A QuerySet is a collection of data from a database. A QuerySet is built up as a list of objects. QuerySets makes it easier to get the data you actually need, by allowing you to filter and order the data.
Since Django 1.8 you have Conditional Expressions so using extra is not necessary anymore.
from django.db.models import Case, When, Value, IntegerField
SomeModel.objects.annotate(
custom_order=Case(
When(id=5, then=Value(1)),
When(id=2, then=Value(2)),
When(id=3, then=Value(3)),
When(id=1, then=Value(4)),
When(id=4, then=Value(5)),
output_field=IntegerField(),
)
).order_by('custom_order')
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