[Django]-Django get the max PK

You can use aggregation to get the Max value. For example, if you wanted the max ID of your Users table:

from django.contrib.auth.models import User
from django.db.models import Max

users = User.objects.all()
max = users.aggregate(Max('id'))

This would give you {'id__max': 10} or whatever the greatest ID is.

This is a bit old, but I came across this same problem and it can be achieved using latest. something like

try:
    return some_table_model.ojects.latest('pk').pk
except some_table_model.DoesNotExist:
    return 0

this is of course assuming that your pk’s are numeric and not composite. Otherwise you could use id or some other field as suggested above

easy. you only need to get pk of the latest object:

YourModel.ojects.latest('pk').pk

You can use this

YourModel.objects.all().order_by(-id).first().id

Here are four different ways to get the max PK, along with the accompanying SQL queries on an OpenMRS database on MySQL 8 (it’s what I had available). Only the aggregation uses MAX():

from django.db import connection
from django.db.models import Max

c0 = Concept.objects.all().order_by('-concept_id').values_list('concept_id')[0]
# this is just the last object in the queryset
# this will *mostly* give you the highest PK, but rather not rely on it
c1 = Concept.objects.last().concept_id
# get the latest object by concept_id
c2 = Concept.objects.latest('concept_id').concept_id
# use aggregation, this is the only one of these methods that uses MAX()
c3 = Concept.objects.all().aggregate(Max('concept_id'))

# show the last 4 SQL queries
connection.queries[-4:]

connection.queries is a list of dicts with sql and times, so we massage it a bit with

print("\n".join([q['sql'].replace("`", "") for q in connection.queries[-4:]]))

to get the following four corresponding SQL queries:

SELECT concept.concept_id FROM concept ORDER BY concept.concept_id DESC LIMIT 1
SELECT concept.concept_id, concept.retired, concept.short_name, concept.description, concept.form_text, concept.datatype_id, concept.class_id, concept.is_set, concept.creator, concept.date_created, concept.version, concept.changed_by, concept.date_changed, concept.retired_by, concept.date_retired, concept.retire_reason, concept.uuid FROM concept ORDER BY concept.concept_id DESC LIMIT 1
SELECT concept.concept_id, concept.retired, concept.short_name, concept.description, concept.form_text, concept.datatype_id, concept.class_id, concept.is_set, concept.creator, concept.date_created, concept.version, concept.changed_by, concept.date_changed, concept.retired_by, concept.date_retired, concept.retire_reason, concept.uuid FROM concept ORDER BY concept.concept_id DESC LIMIT 1
SELECT MAX(concept.concept_id) AS concept_id__max FROM concept