[Django]-Django values_list vs values

values()

Returns a QuerySet that returns dictionaries, rather than model instances, when used as an iterable.

values_list()

Returns a QuerySet that returns list of tuples, rather than model instances, when used as an iterable.

distinct()

distinct are used to eliminate the duplicate elements.

Example:

>>> list(Article.objects.values_list('id', flat=True)) # flat=True will remove the tuples and return the list   
[1, 2, 3, 4, 5, 6]

>>> list(Article.objects.values('id'))
[{'id':1}, {'id':2}, {'id':3}, {'id':4}, {'id':5}, {'id':6}]

values() returns a QuerySet of dictionaries as shown below:

print(User.objects.all().values()) # Return all fields
# <QuerySet [{'id': 1, 'name': 'John'}, {'id': 2, 'name': 'Tom'}]>

print(User.objects.all().values("name")) # Return "name" field
# <QuerySet [{'name': 'John'}, {'name': 'Tom'}]>

values_list() returns a QuerySet of tuples as shown below:

print(User.objects.all().values_list()) # Return all fields
# <QuerySet [(1, 'John'), (2, 'Tom')]>

print(User.objects.all().values_list("name")) # Return "name" field
# <QuerySet [('John',), ('Tom',)]>

values_list() with flat=True returns a QuerySet of values as shown below. *No or one field with flat=True is allowed and one field must be the 1st argument with flat=True which must be the 2nd argument.

print(User.objects.all().values_list(flat=True)) # Return "id" field
# <QuerySet [1, 2]>

print(User.objects.all().values_list("name", flat=True)) # Return "name" field
# <QuerySet ['John', 'Tom']>

print(User.objects.all().values_list(flat=True, "name")) # Error

print(User.objects.all().values_list("id", "name", flat=True)) # Error

You can get the different values with:

set(Article.objects.values_list('comment_id', flat=True))

The best place to understand the difference is at the official documentation on values / values_list. It has many useful examples and explains it very clearly. The django docs are very user freindly.

Here’s a short snippet to keep SO reviewers happy:

values

Returns a QuerySet that returns dictionaries, rather than model instances, when used as an iterable.

And read the section which follows it:

value_list

This is similar to values() except that instead of returning dictionaries, it returns tuples when iterated over.