Merged the queryset-refactor branch into trunk.
This is a big internal change, but mostly backwards compatible with existing
code. Also adds a couple of new features.
Fixed #245, #1050, #1656, #1801, #2076, #2091, #2150, #2253, #2306, #2400, #2430, #2482, #2496, #2676, #2737, #2874, #2902, #2939, #3037, #3141, #3288, #3440, #3592, #3739, #4088, #4260, #4289, #4306, #4358, #4464, #4510, #4858, #5012, #5020, #5261, #5295, #5321, #5324, #5325, #5555, #5707, #5796, #5817, #5987, #6018, #6074, #6088, #6154, #6177, #6180, #6203, #6658
git-svn-id: http://code.djangoproject.com/svn/django/trunk@7477 bcc190cf-cafb-0310-a4f2-bffc1f526a37
2008-04-27 10:50:16 +08:00
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"""
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Various data structures used in query construction.
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Factored out from django.db.models.query so that they can also be used by other
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modules without getting into circular import difficulties.
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"""
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from copy import deepcopy
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from django.utils import tree
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class QueryWrapper(object):
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"""
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A type that indicates the contents are an SQL fragment and the associate
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parameters. Can be used to pass opaque data to a where-clause, for example.
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"""
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def __init__(self, sql, params):
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self.data = sql, params
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class Q(tree.Node):
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"""
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Encapsulates filters as objects that can then be combined logically (using
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& and |).
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"""
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# Connection types
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AND = 'AND'
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OR = 'OR'
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default = AND
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def __init__(self, *args, **kwargs):
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super(Q, self).__init__(children=list(args) + kwargs.items())
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def _combine(self, other, conn):
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if not isinstance(other, Q):
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raise TypeError(other)
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obj = deepcopy(self)
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obj.add(other, conn)
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return obj
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def __or__(self, other):
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return self._combine(other, self.OR)
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def __and__(self, other):
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return self._combine(other, self.AND)
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def __invert__(self):
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obj = deepcopy(self)
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obj.negate()
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return obj
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2008-06-29 17:40:17 +08:00
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def select_related_descend(field, restricted, requested):
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"""
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Returns True if this field should be used to descend deeper for
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select_related() purposes. Used by both the query construction code
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(sql.query.fill_related_selections()) and the model instance creation code
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(query.get_cached_row()).
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"""
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if not field.rel:
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return False
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if field.rel.parent_link:
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return False
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if restricted and field.name not in requested:
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return False
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if not restricted and field.null:
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return False
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return True
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