CODEWITHSUNDEEP
djangopython-3.xlistobjectfilter
2one
2one

Reputation: 1085

Extract values from Django <QuerySet> in Python 3

I have some python code:

UnitTestCollection.objects.filter(unit__type=unit_type)

which outputs data in format:

<QuerySet [<UnitTestCollection: VALUE1>, <UnitTestCollection: VALUE2>...

How can I extract a list of the values only i.e. 

[VALUE1, VALUE2....]

Upvotes: 3

Views: 15045

Answers (2)

Işık Kaplan
Işık Kaplan

Reputation: 2982

Why not a simple list comprehension? 

qs = UnitTestCollection.objects.filter(unit__type=unit_type)
my_values = [item.field_name for item in qs]

Or use values_list() to just fetch the specific field for each item directly in your queryset, with the advantage of lazy evaluation:

qs = UnitTestCollection.objects.filter(unit__type=unit_type)\
                               .values_list('field_name', flat=True)

Upvotes: 11

hancho
hancho

Reputation: 1437

values_list is better than a list comprehension because querysets are lazily evaluated. They won't be executed until you actually need them. 

queryset = UnitTestCollection.objects.filter(unit__type=unit_type).values_list('<insert field>', flat=True)

This will return [field1, field2, field3...]

if you use .values('<insert field>') you'll get [{field: field value1}, {field: field value2}, {field: field value3}...]

Upvotes: 0

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