Fix export json related model (#837)

Author: Vasiliy566

sqladmin/models.py

@@ -1198,7 +1198,7 @@ async def generate() -> AsyncGenerator[str, None]:
 
             for row in data:
                 row_dict = {
-                    name: await self.get_prop_value(row, name)
+                    name: str(await self.get_prop_value(row, name))
                     for name in self._export_prop_names
                 }
                 yield json.dumps(row_dict) + separator

tests/test_views/test_view_sync.py

@@ -1,4 +1,5 @@
 import enum
+import json
 from typing import Any, Generator
 
 import pytest
@@ -741,6 +742,21 @@ def test_export_json(client: TestClient) -> None:
     assert response.text == '[{"name": "Daniel", "status": "ACTIVE"}]'
 
 
+def test_export_json_complex_model(client: TestClient) -> None:
+    with session_maker() as session:
+        user = User(name="Daniel", status="ACTIVE")
+        session.add(user)
+        session.commit()
+        address = Address(user_id=user.id)
+        session.add(address)
+        session.commit()
+
+    response = client.get("/admin/address/export/json")
+    assert response.text == json.dumps(
+        [{"id": "1", "user_id": "1", "user": "User 1", "user.profile.id": "None"}]
+    )
+
+
 def test_export_csv_row_count(client: TestClient) -> None:
     def row_count(resp) -> int:
         return resp.text.count("\r\n") - 1