fix: enhance timestamp handling in PostgresConnector and add corresponding tests

Author: ivictbor

adminforth/dataConnectors/postgres.ts

@@ -205,8 +205,14 @@ class PostgresConnector extends AdminForthBaseConnector implements IAdminForthDa
             if (!value) {
                 return null;
             }
-            if (field._underlineType == 'timestamp' || field._underlineType == 'int') {
-                return dayjs(value.replace(' ', 'T') + 'Z').toISOString();
+            if (field._underlineType == 'timestamp') {
+                if (typeof value == 'string') {
+                    const normalizedValue = value.includes(' ') ? `${value.replace(' ', 'T')}Z` : value;
+                    return dayjs(normalizedValue).toISOString();
+                }
+                return dayjs(value).toISOString();
+            } else if (field._underlineType == 'int') {
+                return dayjs.unix(+value).toISOString();
             } else if (field._underlineType == 'varchar') {
                 return dayjs(value).toISOString();
             } else {

tests/jest_tests/postgres_datetime.test.ts

@@ -0,0 +1,20 @@
+import { AdminForthDataTypes } from '../../adminforth/index.js';
+import PostgresConnector from '../../adminforth/dataConnectors/postgres.js';
+
+describe('PostgresConnector DATETIME normalization', () => {
+  const connector = new PostgresConnector();
+  const timestampField = {
+    type: AdminForthDataTypes.DATETIME,
+    _underlineType: 'timestamp',
+    name: 'created_at',
+    table: 'adminuser',
+  } as any;
+
+  it('parses raw postgres timestamp strings as UTC', () => {
+    expect(connector.getFieldValue(timestampField, '2026-05-09 17:09:21.622')).toBe('2026-05-09T17:09:21.622Z');
+  });
+
+  it('accepts Date objects returned by pg timestamp parsers', () => {
+    expect(connector.getFieldValue(timestampField, new Date('2026-05-09T17:09:21.622Z'))).toBe('2026-05-09T17:09:21.622Z');
+  });
+});