[Django]-Django – how to do this with kwargs

by

5👍

✅

django querysets are lazy, so the actual queries aren’t evaluated until you use the data.

allthings = Thing.objects.filter(**kwargs)

if 'name__startswith' in kwargs:
  allthings = allthings.distinct('id')

No queries should be preformed above unitl you actually use the data. This is great for filtering queries as you wish to do

From the docs:

QuerySets are lazy – the act of creating a QuerySet doesn’t involve any database activity. You can stack filters together all day long, and Django won’t actually run the query until the QuerySet is evaluated. Take a look at this example:

>>> q = Entry.objects.filter(headline__startswith="What")
>>> q = q.filter(pub_date__lte=datetime.date.today())
>>> q = q.exclude(body_text__icontains="food")
>>> print(q)

Though this looks like three database hits, in fact it hits the database only once, at the last line (print(q)). In general, the results of a QuerySet aren’t fetched from the database until you “ask” for them. When you do, the QuerySet is evaluated by accessing the database. For more details on exactly when evaluation takes place, see When QuerySets are evaluated.

👤dm03514

1👍

You can use models.Q to create dynamic queries in django.

query = models.Q(name__startswith=somename)

query &= models.Q('color__iexact':'somecolor')

all_things = Thing.objects.filter(query).distinct('name')

Also read
Constructing Django filter queries dynamically with args and kwargs

👤Pratik Mandrekar

Leave a comment