generate update query using django orm

Question

I need to implement this query using django orm:

update table set field=field+1 where id=id

I don't whant to use this:

o = model.objects.get(id=id)
o.field+=1
o.save()

because it use select and when update, and not thread safe.

How to implement this via orm?

Answer 1

Both the previous answerers have part of the solution: you should use update in conjunction with F():

Model.objects.filter(id=id).update(field=F('field') +1))

Note this does an in-place UPDATE without any need for SELECT at all.

Answer 2

for django v 2.2 (and maybe 3+) SQL statement compilation function could be:

from django.db.models.sql.subqueries import UpdateQuery

def compile_update_query(query_set, update_kwargs):
    query = query_set.query.chain(UpdateQuery)
    query.add_update_values(update_kwargs)
    return str(query)

where query_set is MyShinyModel.objects.filter(id=42) and update_kwargs is a dictionary of model fields to update