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Refactored the empty/full result logic in WhereNode.as_sql()
Made sure the WhereNode.as_sql() handles various EmptyResultSet and FullResultSet conditions correctly. Also, got rid of the FullResultSet exception class. It is now represented by '', [] return value in the as_sql() methods.
This commit is contained in:
Anssi Kääriäinen
parent
2b9fb2e644
commit
bd283aa844
@ -6,9 +6,6 @@ the SQL domain.
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class EmptyResultSet(Exception):
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pass
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class FullResultSet(Exception):
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pass
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class MultiJoin(Exception):
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"""
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Used by join construction code to indicate the point at which a
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@ -10,7 +10,7 @@ from itertools import repeat
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from django.utils import tree
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from django.db.models.fields import Field
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from django.db.models.sql.datastructures import EmptyResultSet, FullResultSet
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from django.db.models.sql.datastructures import EmptyResultSet
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from django.db.models.sql.aggregates import Aggregate
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# Connection types
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@ -75,17 +75,21 @@ class WhereNode(tree.Node):
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def as_sql(self, qn, connection):
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"""
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Returns the SQL version of the where clause and the value to be
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substituted in. Returns None, None if this node is empty.
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If 'node' is provided, that is the root of the SQL generation
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(generally not needed except by the internal implementation for
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recursion).
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substituted in. Returns '', [] if this node matches everything,
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None, [] if this node is empty, and raises EmptyResultSet if this
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node can't match anything.
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"""
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if not self.children:
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return None, []
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# Note that the logic here is made slightly more complex than
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# necessary because there are two kind of empty nodes: Nodes
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# containing 0 children, and nodes that are known to match everything.
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# A match-everything node is different than empty node (which also
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# technically matches everything) for backwards compatibility reasons.
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# Refs #5261.
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result = []
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result_params = []
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empty = True
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everything_childs, nothing_childs = 0, 0
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non_empty_childs = len(self.children)
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for child in self.children:
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try:
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if hasattr(child, 'as_sql'):
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@ -93,39 +97,48 @@ class WhereNode(tree.Node):
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else:
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# A leaf node in the tree.
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sql, params = self.make_atom(child, qn, connection)
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except EmptyResultSet:
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if self.connector == AND and not self.negated:
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# We can bail out early in this particular case (only).
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raise
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elif self.negated:
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empty = False
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continue
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except FullResultSet:
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if self.connector == OR:
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if self.negated:
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empty = True
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break
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# We match everything. No need for any constraints.
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return '', []
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if self.negated:
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empty = True
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continue
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empty = False
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nothing_childs += 1
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else:
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if sql:
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result.append(sql)
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result_params.extend(params)
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if empty:
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else:
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if sql is None:
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# Skip empty childs totally.
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non_empty_childs -= 1
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continue
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everything_childs += 1
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# Check if this node matches nothing or everything.
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# First check the amount of full nodes and empty nodes
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# to make this node empty/full.
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if self.connector == AND:
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full_needed, empty_needed = non_empty_childs, 1
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else:
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full_needed, empty_needed = 1, non_empty_childs
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# Now, check if this node is full/empty using the
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# counts.
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if empty_needed - nothing_childs <= 0:
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if self.negated:
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return '', []
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else:
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raise EmptyResultSet
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if full_needed - everything_childs <= 0:
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if self.negated:
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raise EmptyResultSet
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else:
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return '', []
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if non_empty_childs == 0:
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# All the child nodes were empty, so this one is empty, too.
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return None, []
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conn = ' %s ' % self.connector
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sql_string = conn.join(result)
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if sql_string:
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if self.negated:
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sql_string = 'NOT (%s)' % sql_string
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elif len(self.children) != 1:
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if len(result) > 1:
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sql_string = '(%s)' % sql_string
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if self.negated:
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sql_string = 'NOT %s' % sql_string
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return sql_string, result_params
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def make_atom(self, child, qn, connection):
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@ -261,7 +274,7 @@ class EverythingNode(object):
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"""
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def as_sql(self, qn=None, connection=None):
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raise FullResultSet
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return '', []
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def relabel_aliases(self, change_map, node=None):
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return
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@ -10,6 +10,8 @@ from django.core.exceptions import FieldError
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from django.db import DatabaseError, connection, connections, DEFAULT_DB_ALIAS
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from django.db.models import Count
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from django.db.models.query import Q, ITER_CHUNK_SIZE, EmptyQuerySet
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from django.db.models.sql.where import WhereNode, EverythingNode, NothingNode
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from django.db.models.sql.datastructures import EmptyResultSet
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from django.test import TestCase, skipUnlessDBFeature
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from django.test.utils import str_prefix
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from django.utils import unittest
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@ -1316,10 +1318,23 @@ class Queries5Tests(TestCase):
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)
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def test_ticket5261(self):
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# Test different empty excludes.
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self.assertQuerysetEqual(
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Note.objects.exclude(Q()),
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['<Note: n1>', '<Note: n2>']
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)
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self.assertQuerysetEqual(
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Note.objects.filter(~Q()),
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['<Note: n1>', '<Note: n2>']
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)
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self.assertQuerysetEqual(
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Note.objects.filter(~Q()|~Q()),
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['<Note: n1>', '<Note: n2>']
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)
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self.assertQuerysetEqual(
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Note.objects.exclude(~Q()&~Q()),
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['<Note: n1>', '<Note: n2>']
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)
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class SelectRelatedTests(TestCase):
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@ -2020,3 +2035,74 @@ class ProxyQueryCleanupTest(TestCase):
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self.assertEqual(qs.count(), 1)
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str(qs.query)
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self.assertEqual(qs.count(), 1)
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class WhereNodeTest(TestCase):
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class DummyNode(object):
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def as_sql(self, qn, connection):
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return 'dummy', []
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def test_empty_full_handling_conjunction(self):
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qn = connection.ops.quote_name
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w = WhereNode(children=[EverythingNode()])
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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w.negate()
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w = WhereNode(children=[NothingNode()])
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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w = WhereNode(children=[EverythingNode(), EverythingNode()])
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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w.negate()
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w = WhereNode(children=[EverythingNode(), self.DummyNode()])
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self.assertEquals(w.as_sql(qn, connection), ('dummy', []))
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w = WhereNode(children=[self.DummyNode(), self.DummyNode()])
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self.assertEquals(w.as_sql(qn, connection), ('(dummy AND dummy)', []))
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), ('NOT (dummy AND dummy)', []))
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w = WhereNode(children=[NothingNode(), self.DummyNode()])
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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def test_empty_full_handling_disjunction(self):
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qn = connection.ops.quote_name
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w = WhereNode(children=[EverythingNode()], connector='OR')
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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w.negate()
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w = WhereNode(children=[NothingNode()], connector='OR')
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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w = WhereNode(children=[EverythingNode(), EverythingNode()], connector='OR')
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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w.negate()
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w = WhereNode(children=[EverythingNode(), self.DummyNode()], connector='OR')
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self.assertEquals(w.as_sql(qn, connection), ('', []))
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w.negate()
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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w = WhereNode(children=[self.DummyNode(), self.DummyNode()], connector='OR')
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self.assertEquals(w.as_sql(qn, connection), ('(dummy OR dummy)', []))
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), ('NOT (dummy OR dummy)', []))
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w = WhereNode(children=[NothingNode(), self.DummyNode()], connector='OR')
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self.assertEquals(w.as_sql(qn, connection), ('dummy', []))
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), ('NOT dummy', []))
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def test_empty_nodes(self):
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qn = connection.ops.quote_name
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empty_w = WhereNode()
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w = WhereNode(children=[empty_w, empty_w])
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self.assertEquals(w.as_sql(qn, connection), (None, []))
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), (None, []))
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w.connector = 'OR'
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self.assertEquals(w.as_sql(qn, connection), (None, []))
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w.negate()
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self.assertEquals(w.as_sql(qn, connection), (None, []))
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w = WhereNode(children=[empty_w, NothingNode()], connector='OR')
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self.assertRaises(EmptyResultSet, w.as_sql, qn, connection)
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