def process_rhs(self, compiler, connection):
db_rhs = getattr(self.rhs, "_db", None)
if db_rhs is not None and db_rhs != connection.alias:
raise ValueError(
"Subqueries aren't allowed across different databases. Force "
"the inner query to be evaluated using `list(inner_query)`."
)
if self.rhs_is_direct_value():
# Remove None from the list as NULL is never equal to anything.
try:
rhs = OrderedSet(self.rhs)
rhs.discard(None)
except TypeError: # Unhashable items in self.rhs
rhs = [r for r in self.rhs if r is not None]
if not rhs:
raise EmptyResultSet
# rhs should be an iterable; use batch_process_rhs() to
# prepare/transform those values.
sqls, sqls_params = self.batch_process_rhs(compiler, connection, rhs)
placeholder = "(" + ", ".join(sqls) + ")"
return (placeholder, sqls_params)
else:
from django.db.models.sql.query import Query # avoid circular import
if isinstance(self.rhs, Query):
query = self.rhs
query.clear_ordering(clear_default=True)
if not query.has_select_fields:
query.clear_select_clause()
query.add_fields(["pk"])
return super().process_rhs(compiler, connection)
def process_rhs(self, compiler, connection):
db_rhs = getattr(self.rhs, '_db', None)
if db_rhs is not None and db_rhs != connection.alias:
raise ValueError(
"Subqueries aren't allowed across different databases. Force "
"the inner query to be evaluated using `list(inner_query)`.")
if self.rhs_is_direct_value():
# Remove None from the list as NULL is never equal to anything.
try:
rhs = OrderedSet(self.rhs)
rhs.discard(None)
except TypeError: # Unhashable items in self.rhs
rhs = [r for r in self.rhs if r is not None]
if not rhs:
raise EmptyResultSet
# rhs should be an iterable; use batch_process_rhs() to
# prepare/transform those values.
sqls, sqls_params = self.batch_process_rhs(compiler, connection,
rhs)
placeholder = '(' + ', '.join(sqls) + ')'
return (placeholder, sqls_params)
else:
if not getattr(self.rhs, 'has_select_fields', True):
self.rhs.clear_select_clause()
self.rhs.add_fields(['pk'])
return super().process_rhs(compiler, connection)
def test_discard(self):
s = OrderedSet()
self.assertEqual(len(s), 0)
s.add(1)
s.discard(2)
self.assertEqual(len(s), 1)
