[3.1.x] Fixed #31835 -- Dropped support for JSONField __contains lookup on Oracle.

The current implementation works only for basic examples without
supporting nested structures and doesn't follow "the general principle
that the contained object must match the containing object as to
structure and data contents, possibly after discarding some
non-matching array elements or object key/value pairs from the
containing object".
Backport of 02447fb133 from master

django/db/models/fields/json.py

@@ -146,24 +146,7 @@ class DataContains(PostgresOperatorLookup):
         return 'JSON_CONTAINS(%s, %s)' % (lhs, rhs), params
 
     def as_oracle(self, compiler, connection):
-        if isinstance(self.rhs, KeyTransform):
+        raise NotSupportedError('contains lookup is not supported on Oracle.')
-            return HasKey(self.lhs, self.rhs).as_oracle(compiler, connection)
-        lhs, lhs_params = self.process_lhs(compiler, connection)
-        params = tuple(lhs_params)
-        sql = (
-            "JSON_QUERY(%s, '$%s' WITH WRAPPER) = "
-            "JSON_QUERY('%s', '$.value' WITH WRAPPER)"
-        )
-        rhs = json.loads(self.rhs)
-        if isinstance(rhs, dict):
-            if not rhs:
-                return "DBMS_LOB.SUBSTR(%s) LIKE '{%%%%}'" % lhs, params
-            return ' AND '.join([
-                sql % (
-                    lhs, '.%s' % json.dumps(key), json.dumps({'value': value}),
-                ) for key, value in rhs.items()
-            ]), params
-        return sql % (lhs, '', json.dumps({'value': rhs})), params
 
 
 class ContainedBy(PostgresOperatorLookup):

docs/topics/db/queries.txt

@@ -960,6 +960,10 @@ contained in the top-level of the field. For example::
     >>> Dog.objects.filter(data__contains={'breed': 'collie'})
     <QuerySet [<Dog: Meg>]>
 
+.. admonition:: Oracle
+
+    ``contains`` is not supported on Oracle.
+
 .. fieldlookup:: jsonfield.contained_by
 
 ``contained_by``

tests/model_fields/test_jsonfield.py

@@ -426,6 +426,10 @@ class TestQuerying(TestCase):
             [self.objs[3], self.objs[4], self.objs[6]],
         )
 
+    @skipIf(
+        connection.vendor == 'oracle',
+        "Oracle doesn't support contains lookup.",
+    )
     def test_contains(self):
         tests = [
             ({}, self.objs[2:5] + self.objs[6:8]),
@@ -441,6 +445,17 @@ class TestQuerying(TestCase):
                 qs = NullableJSONModel.objects.filter(value__contains=value)
                 self.assertSequenceEqual(qs, expected)
 
+    @skipUnless(
+        connection.vendor == 'oracle',
+        "Oracle doesn't support contains lookup.",
+    )
+    def test_contains_unsupported(self):
+        msg = 'contains lookup is not supported on Oracle.'
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            NullableJSONModel.objects.filter(
+                value__contains={'baz': {'a': 'b', 'c': 'd'}},
+            ).get()
+
     @skipUnlessDBFeature('supports_primitives_in_json_field')
     def test_contains_primitives(self):
         for value in self.primitives:
@@ -647,12 +662,12 @@ class TestQuerying(TestCase):
             ('value__baz__has_key', 'c'),
             ('value__baz__has_keys', ['a', 'c']),
             ('value__baz__has_any_keys', ['a', 'x']),
-            ('value__contains', KeyTransform('bax', 'value')),
             ('value__has_key', KeyTextTransform('foo', 'value')),
         )
-        # contained_by lookup is not supported on Oracle.
+        # contained_by and contains lookups are not supported on Oracle.
         if connection.vendor != 'oracle':
             tests += (
+                ('value__contains', KeyTransform('bax', 'value')),
                 ('value__baz__contained_by', {'a': 'b', 'c': 'd', 'e': 'f'}),
                 (
                     'value__contained_by',