CODEWITHSUNDEEP
pythondjangolistloops
j1ncx
j1ncx

Reputation: 25

Adding contents of a queryset to a list in Django/Python

I'm pretty new to Django. I'm trying to iterate over my queryset and add the field which happens to be called 'id' of each to a new list.

My end result should be a list looking something like this (for example): [1, 2, 3, 7, 10]

My code looks like this:

my_list = []

for foo in bar:
    number = foo.id
    my_list += number

I'm getting this error: TypeError: 'long' object is not iterable

The type of foo.id is long

I have tried changing the foo.id to an int or str using:

number = str(number)

Have also tried the solution here (I'm using Python 2.7): TypeError: 'long' object is not iterable but I get this: AttributeError: 'QuerySet' object has no attribute 'iteritems'

Any help much appreciated!

Upvotes: 1

Views: 4825

Answers (2)

bruno desthuilliers
bruno desthuilliers

Reputation: 77902

As for why your code raises an error: you'd have to use my_list.append(number) (my_list += anything is a shortcut for my_list.extends(anything) which expects an iterable and will append all values from this iterable to my_list).

Now actually, the pythonic way here would be to use a list comprehension instead, ie :

my_list = [foo.id for foo in bar]

But since it's about a Django queryset, the right solution is to use QuerySet.values_list():

bar = MyModel.objects.values_list("id", flat=True)

which will result in bar being an iterable over your queryset's 'id' values. And if you really need a list, then you just have to pass bar to the list constructor:

my_list = list(bar)

Upvotes: 5

Darshit
Darshit

Reputation: 430

It is bad practice to iterate over queryset to get id of each object. I suggest to use values_list() like. which will give you list of id of each object in queryset.

ids = bar.values_list('id', flat=True)

Upvotes: 0

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