Python/Django — what is the difference between the “and” operator and the “&” operator

Question

I have a interesting Django problem.

Consider the following:

Model.objects.filter(Q(id=\'test1\') and Q(id=\'test2\'))

this returns the

Answer 1

If you want Django ORM to return test1 and test2, you should use :

Model.objects.filter(Q(id='test1') | Q(id='test2'))

Model.objects.filter(Q(id='test1') & Q(id='test2')) means return model objects whose id is test1 while its is test2 at the same time. Of course, django will return an empty QuerySet.

and is a boolean operator in Python. For operation x and y the result is if x is false, then x, else y. Thus Q(id='test1') and Q(id='test2') equals Q(id='test1'), it is not what you want.

&/| is the the bitwise and/or operator.

BTW, there's no way to override the boolean operator, but you can override &/| operators in your class by define a method named __and__ / __or__.

below is the source code of the django Q object[github]:

class Q(tree.Node):
    """
    Encapsulates filters as objects that can then be combined logically (using
    & and |).
    """
    # Connection types
    AND = 'AND'
    OR = 'OR'
    default = AND

    def __or__(self, other):
        return self._combine(other, self.OR)

    def __and__(self, other):
        return self._combine(other, self.AND)
    ...