app/django/db/models/query_utils.py
author Todd Larsen <tlarsen@google.com>
Thu, 28 Aug 2008 23:54:35 +0000
changeset 119 50d8d58dcd7c
parent 54 03e267d67478
child 323 ff1a9aa48cfd
permissions -rw-r--r--
Add soc.views.simple containing (initially) two simple template views. templateWithLinkName() is a view that can replace most public() read-only views. errorResponse() is a view that renders an error page for out_of_band.ErrorResponse exceptions. Also, change response_helpers.respond() to accept keyword arguments to pass to http.HttpResponse(). (errorResponse() makes use of this new respond() feature.) Patch by: Todd Larsen Review by: to-be-reviewed

"""
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