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 = mod         


        

Answer 1

You can use update, details can be found in the documentation

Answer 2

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 3

If you need to convert the UPDATE ORM query to UPDATE SQL statement without performing it

The update() method is applied instantly and returns the number of rows matched by the query (django 1.8 docs)

def generate_update_sql(queryset, update_kwargs):
    """  [checked on django 1.8]
    Converts queryset with update_kwargs
    like if was: queryset.update(**update_kwargs)
    """
    from django.db.models import sql

    query = queryset.query.clone(sql.UpdateQuery)
    query.add_update_values(update_kwargs)
    compiler = query.get_compiler(queryset.db)
    sql, params = compiler.as_sql()
    return sql % params

Usage

qs = Event.objects.exclude(app='some')
update_kwargs = dict(description='test', action='action')
generate_update_sql(qs, update_kwargs) 

Will return

UPDATE `api_event` SET `description` = test, `action` = action WHERE NOT (`api_event`.`app` = some)