问题
From an example you can see a multiple OR query filter:
Article.objects.filter(Q(pk=1) | Q(pk=2) | Q(pk=3))
For example, this results in:
[<Article: Hello>, <Article: Goodbye>, <Article: Hello and goodbye>]
However, I want to create this query filter from a list. How to do that?
e.g. [1, 2, 3] -> Article.objects.filter(Q(pk=1) | Q(pk=2) | Q(pk=3))
回答1:
You could chain your queries as follows:
values = [1,2,3]
# Turn list of values into list of Q objects
queries = [Q(pk=value) for value in values]
# Take one Q object from the list
query = queries.pop()
# Or the Q object with the ones remaining in the list
for item in queries:
query |= item
# Query the model
Article.objects.filter(query)
回答2:
To build more complex queries there is also the option to use built in Q() object's constants Q.OR and Q.AND together with the add() method like so:
list = [1, 2, 3]
# it gets a bit more complicated if we want to dynamically build
# OR queries with dynamic/unknown db field keys, let's say with a list
# of db fields that can change like the following
# list_with_strings = ['dbfield1', 'dbfield2', 'dbfield3']
# init our q objects variable to use .add() on it
q_objects = Q()
# loop trough the list and create an OR condition for each item
for item in list:
q_objects.add(Q(pk=item), Q.OR)
# for our list_with_strings we can do the following
# q_objects.add(Q(**{item: 1}), Q.OR)
queryset = Article.objects.filter(q_objects)
# sometimes the following is helpful for debugging (returns the SQL statement)
# print queryset.query
回答3:
A shorter way of writing Dave Webb's answer using python's reduce function:
# For Python 3 only
from functools import reduce
values = [1,2,3]
# Turn list of values into one big Q objects
query = reduce(lambda q,value: q|Q(pk=value), values, Q())
# Query the model
Article.objects.filter(query)
回答4:
from functools import reduce
from operator import or_
from django.db.models import Q
values = [1, 2, 3]
query = reduce(or_, (Q(pk=x) for x in values))
回答5:
Maybe it's better to use sql IN statement.
Article.objects.filter(id__in=[1, 2, 3])
See queryset api reference.
If you really need to make queries with dynamic logic, you can do something like this (ugly + not tested):
query = Q(field=1)
for cond in (2, 3):
query = query | Q(field=cond)
Article.objects.filter(query)
回答6:
See the docs:
>>> Blog.objects.in_bulk([1])
{1: <Blog: Beatles Blog>}
>>> Blog.objects.in_bulk([1, 2])
{1: <Blog: Beatles Blog>, 2: <Blog: Cheddar Talk>}
>>> Blog.objects.in_bulk([])
{}
Note that this method only works for primary key lookups, but that seems to be what you're trying to do.
So what you want is:
Article.objects.in_bulk([1, 2, 3])
回答7:
In case we want to programmatically set what db field we want to query:
import operator
questions = [('question__contains', 'test'), ('question__gt', 23 )]
q_list = [Q(x) for x in questions]
Poll.objects.filter(reduce(operator.or_, q_list))
回答8:
Solution which use reduce
and or_
operators to filter by multiply fields.
from functools import reduce
from operator import or_
from django.db.models import Q
filters = {'field1': [1, 2], 'field2': ['value', 'other_value']}
qs = Article.objects.filter(
reduce(or_, (Q(**{f'{k}__in': v}) for k, v in filters.items()))
)
p.s. f
is a new format strings literal. It was introduced in python 3.6
回答9:
You can use the |= operator to programmatically update a query using Q objects.
回答10:
This one is for dynamic pk list:
pk_list = qs.values_list('pk', flat=True) # i.e [] or [1, 2, 3]
if len(pk_list) == 0:
Article.objects.none()
else:
q = None
for pk in pk_list:
if q is None:
q = Q(pk=pk)
else:
q = q | Q(pk=pk)
Article.objects.filter(q)
回答11:
Another option I wasn't aware of until recently - QuerySet
also overrides the &
, |
, ~
, etc, operators. The other answers that OR Q objects are a better solution to this question, but for the sake of interest/argument, you can do:
id_list = [1, 2, 3]
q = Article.objects.filter(pk=id_list[0])
for i in id_list[1:]:
q |= Article.objects.filter(pk=i)
str(q.query)
will return one query with all the filters in the WHERE
clause.
回答12:
easy..
from django.db.models import Q
import you model
args = (Q(visibility=1)|(Q(visibility=0)&Q(user=self.user))) #Tuple
parameters={} #dic
order = 'create_at'
limit = 10
Models.objects.filter(*args,**parameters).order_by(order)[:limit]
来源:https://stackoverflow.com/questions/852414/how-to-dynamically-compose-an-or-query-filter-in-django