Refs #26511 -- Fixed json.KeyTextTransform() on MySQL/MariaDB.

django/db/models/fields/json.py

@@ -4,6 +4,7 @@ from django import forms
 from django.core import checks, exceptions
 from django.db import NotSupportedError, connections, router
 from django.db.models import lookups
+from django.db.models.fields import TextField
 from django.db.models.lookups import PostgresOperatorLookup, Transform
 from django.utils.translation import gettext_lazy as _
 
@@ -366,6 +367,17 @@ class KeyTransform(Transform):
 class KeyTextTransform(KeyTransform):
     postgres_operator = "->>"
     postgres_nested_operator = "#>>"
+    output_field = TextField()
+
+    def as_mysql(self, compiler, connection):
+        if connection.mysql_is_mariadb:
+            # MariaDB doesn't support -> and ->> operators (see MDEV-13594).
+            sql, params = super().as_mysql(compiler, connection)
+            return "JSON_UNQUOTE(%s)" % sql, params
+        else:
+            lhs, params, key_transforms = self.preprocess_lhs(compiler, connection)
+            json_path = compile_json_path(key_transforms)
+            return "(%s ->> %%s)" % lhs, tuple(params) + (json_path,)
 
 
 class KeyTransformTextLookupMixin: