general: ensure jsonfields are using jsonb columns (fixup, #52915)

combo/apps/wcs/migrations/0026_text_to_jsonb.py

@@ -2,7 +2,7 @@
 
 from django.db import migrations
 
-from combo.db.utils import EnsureJsonbType
+from combo.utils.db import EnsureJsonbType
 
 
 class Migration(migrations.Migration):

combo/utils/db.py

@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from django.db import connection
 from django.db.migrations.operations.base import Operation
 
 
@@ -29,16 +30,17 @@ class EnsureJsonbType(Operation):
         pass
 
     def database_forwards(self, app_label, schema_editor, from_state, to_state):
-        model = from_state.apps.get_model(app_label, self.model_name)
-        table_name = model._meta.db_table
-        field = model._meta.get_field(self.field_name)
-        _, column_name = field.get_attname_column()
-        with schema_editor.connection.cursor() as cursor:
-            cursor.execute(
-                'ALTER TABLE {table} ALTER COLUMN {col} TYPE jsonb USING {col}::jsonb;'.format(
-                    table=table_name, col=column_name
+        if connection.vendor == 'postgresql':
+            model = from_state.apps.get_model(app_label, self.model_name)
+            table_name = model._meta.db_table
+            field = model._meta.get_field(self.field_name)
+            _, column_name = field.get_attname_column()
+            with schema_editor.connection.cursor() as cursor:
+                cursor.execute(
+                    'ALTER TABLE {table} ALTER COLUMN {col} TYPE jsonb USING {col}::jsonb;'.format(
+                        table=table_name, col=column_name
+                    )
                 )
-            )
 
     def database_backwards(self, app_label, schema_editor, from_state, to_state):
         pass

tests/test_ensure_jsonbfields.py

@@ -1,7 +1,6 @@
 # -*- coding: utf-8 -*-
 
 import pytest
-
 from django.core.management import call_command
 from django.db import connection
 
@@ -14,9 +13,6 @@ def test_ensure_jsonb_fields():
         'bank_data',
         'bank_result',
         'cached_json',
-        'cached_json',
-        'categories',
-        'categories',
         'categories',
         'filter_params',
         'filters',