Save a list of objects in django

Question

I am using django 1.5 and i am trying to do something like this :

    quotes = formset.save()
    user = client_form.save()
    for quote in quotes:
        quote.client = user
    quotes.save()

But lists dont have a save() method so is there some built in functionality to do something similar ?

I found this nswer on SO Question about batch save objects in Django

Is it still True with django 1.5 ? Is there no way to avoid the save() call on each object of the list ?

here is my actual view code:

def new_quote(request):
    QuoteLineFormSet = modelformset_factory(QuoteLine, form=QuoteLineForm, extra=2)

    if request.method == 'POST':
        formset = QuoteLineFormSet(request.POST, request.FILES, queryset=QuoteLine.objects.none())
        quote_form = QuoteForm(request.POST, request.FILES)
        if formset.is_valid() and quote_form.is_valid():
            quote_lines = formset.save(commit=False)
            #quote_lines = formset.get_queryset()
            quote = quote_form.save()
            for quote_line in quote_lines:
                quote_line.quote = quote
                quote_line.save()
            request.session['quote_id'] = quote.id
            return HttpResponseRedirect(reverse('new_client'))
    else:
        formset = QuoteLineFormSet(queryset=QuoteLine.objects.none())
        quote_form = QuoteForm()

    return render(request, 'request_quote_form.html', {
        'formset': formset,
        'quote_form': quote_form,
    })

My solution for now

    quote_line_ids = [item.pk for item in formset.save()]
    quote_lines_qs = QuoteLine.objects.filter(pk__in=quote_line_ids)
    quote = quote_form.save()
    quote_lines_qs.update(quote=quote)

score 5 · Answer 1 · edited May 23 '17 at 12:25

5

You can use update() method on a queryset.

Also see this question and answer: Django: form that updates X amount of models

edited May 23 '17 at 12:25

Community

1
1

answered Apr 17 '13 at 11:05

alecxe

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useful but i don't use a queryset – maazza Apr 17 '13 at 11:59
1

how ? i tried a few things but formset.get_queryset() always return an empty list – maazza Apr 17 '13 at 12:23
Thank you. That's because you're setting an empty queryset while initializing `QuoteLineFormSet` (see [docs](https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#changing-the-queryset)). So, my solution won't work in your case, sorry. – alecxe Apr 17 '13 at 12:50

score 2 · Accepted Answer · answered Apr 17 '13 at 12:10

When you do formset.save(), it hits database as many times as number of forms in the formset. So, its n hits if the number of element in the formset is n.

So, you can have commit=False on the formset which will not hit the db at all. Then you can update the objects and call save() on each object. So, your database calls remain n times.

#doesn't hit the database at all
quotes = formset.save(commit=False)
user = client_form.save()
for quote in quotes:
    quote.client = user
    #hits the db
    quote.save()

Not sure if you can do this entire operation in one call to db.

score 0 · Answer 3 · answered Apr 17 '13 at 11:36

0

Also have look at this link. Very straightforward easy-to-use approach. From the blog:

for x in seq:
   o = SomeObject()
   o.foo = x
   o.save()

becomes

l = []
for x in seq:
    o = SomeObject()
    o.foo = x
    l.append(o)
insert_many(l)

answered Apr 17 '13 at 11:36

LarsVegas

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i would like to avoid some third party code if it is possible – maazza Apr 17 '13 at 12:12

Save a list of objects in django

3 Answers3