app/django/db/models/query_utils.py
author Todd Larsen <tlarsen@google.com>
Wed, 01 Oct 2008 00:35:29 +0000
changeset 221 9cca97feadaa
parent 54 03e267d67478
child 323 ff1a9aa48cfd
permissions -rw-r--r--
Add sidebar menu items for /site/docs/list and /site/docs/edit. They do not currently have view functions attached, but there are other links in the mock-up portion of the sidebar that don't currently work, either. The goal is to commit the /site/docs/list and /site/docs/edit changes in small bits that don't break anyone else.

"""
Various data structures used in query construction.

Factored out from django.db.models.query so that they can also be used by other
modules without getting into circular import difficulties.
"""

from copy import deepcopy

from django.utils import tree

class QueryWrapper(object):
    """
    A type that indicates the contents are an SQL fragment and the associate
    parameters. Can be used to pass opaque data to a where-clause, for example.
    """
    def __init__(self, sql, params):
        self.data = sql, params

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 __init__(self, *args, **kwargs):
        super(Q, self).__init__(children=list(args) + kwargs.items())

    def _combine(self, other, conn):
        if not isinstance(other, Q):
            raise TypeError(other)
        obj = deepcopy(self)
        obj.add(other, conn)
        return obj

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

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

    def __invert__(self):
        obj = deepcopy(self)
        obj.negate()
        return obj