fix: make sure data is json serializable (#4269)

* Refactor `recursive_serialize_or_str` function into a separate module

- Moved the `recursive_serialize_or_str` function from `schema.py` to a new `serialize.py` module for better modularity and reusability.
- Updated imports in `data.py`, `artifact.py`, and `schema.py` to reflect the new location of the `recursive_serialize_or_str` function.
- Enhanced the `recursive_serialize_or_str` function to handle `datetime` objects by converting them to ISO format.

* Enhance data serialization with recursive handling in `to_json` method

---------

Co-authored-by: Edwin Jose <edwin.jose@datastax.com>

src/backend/base/langflow/schema/artifact.py

@@ -7,7 +7,7 @@ from pydantic import BaseModel
 
 from langflow.schema.data import Data
 from langflow.schema.message import Message
-from langflow.schema.schema import recursive_serialize_or_str
+from langflow.schema.serialize import recursive_serialize_or_str
 
 
 class ArtifactType(str, Enum):

src/backend/base/langflow/schema/data.py

@@ -8,6 +8,7 @@ from langchain_core.prompts.image import ImagePromptTemplate
 from loguru import logger
 from pydantic import BaseModel, model_serializer, model_validator
 
+from langflow.schema.serialize import recursive_serialize_or_str
 from langflow.utils.constants import MESSAGE_SENDER_AI, MESSAGE_SENDER_USER
 
 if TYPE_CHECKING:
@@ -199,6 +200,7 @@ class Data(BaseModel):
         # return a JSON string representation of the Data atributes
         try:
             data = {k: v.to_json() if hasattr(v, "to_json") else v for k, v in self.data.items()}
+            data = recursive_serialize_or_str(data)
             return json.dumps(data, indent=4)
         except Exception:  # noqa: BLE001
             logger.opt(exception=True).debug("Error converting Data to JSON")

src/backend/base/langflow/schema/schema.py

@@ -1,14 +1,13 @@
-from collections.abc import AsyncIterator, Generator, Iterator
+from collections.abc import Generator
 from enum import Enum
 from typing import Literal
 
-from loguru import logger
 from pydantic import BaseModel
-from pydantic.v1 import BaseModel as BaseModelV1
 from typing_extensions import TypedDict
 
 from langflow.schema.data import Data
 from langflow.schema.message import Message
+from langflow.schema.serialize import recursive_serialize_or_str
 
 INPUT_FIELD_NAME = "input_value"
 
@@ -113,38 +112,3 @@ def build_output_logs(vertex, result) -> dict:
         outputs |= {name: OutputValue(message=message, type=_type).model_dump()}
 
     return outputs
-
-
-def recursive_serialize_or_str(obj):
-    try:
-        if isinstance(obj, str):
-            return obj
-        if isinstance(obj, dict):
-            return {k: recursive_serialize_or_str(v) for k, v in obj.items()}
-        if isinstance(obj, list):
-            return [recursive_serialize_or_str(v) for v in obj]
-        if isinstance(obj, BaseModel | BaseModelV1):
-            if hasattr(obj, "model_dump"):
-                obj_dict = obj.model_dump()
-            elif hasattr(obj, "dict"):
-                obj_dict = obj.dict()
-            return {k: recursive_serialize_or_str(v) for k, v in obj_dict.items()}
-
-        if isinstance(obj, AsyncIterator | Generator | Iterator):
-            # contain memory addresses
-            # without consuming the iterator
-            # return list(obj) consumes the iterator
-            # return f"{obj}" this generates '<generator object BaseChatModel.stream at 0x33e9ec770>'
-            # it is not useful
-            return "Unconsumed Stream"
-        if hasattr(obj, "dict"):
-            return {k: recursive_serialize_or_str(v) for k, v in obj.dict().items()}
-        if hasattr(obj, "model_dump"):
-            return {k: recursive_serialize_or_str(v) for k, v in obj.model_dump().items()}
-        if isinstance(obj, type) and issubclass(obj, BaseModel):
-            # This a type BaseModel and not an instance of it
-            return repr(obj)
-        return str(obj)
-    except Exception:  # noqa: BLE001
-        logger.debug(f"Cannot serialize object {obj}")
-        return str(obj)

src/backend/base/langflow/schema/serialize.py

@@ -0,0 +1,43 @@
+from collections.abc import AsyncIterator, Generator, Iterator
+from datetime import datetime
+
+from loguru import logger
+from pydantic import BaseModel
+from pydantic.v1 import BaseModel as BaseModelV1
+
+
+def recursive_serialize_or_str(obj):
+    try:
+        if isinstance(obj, str):
+            return obj
+        if isinstance(obj, datetime):
+            return obj.isoformat()
+        if isinstance(obj, dict):
+            return {k: recursive_serialize_or_str(v) for k, v in obj.items()}
+        if isinstance(obj, list):
+            return [recursive_serialize_or_str(v) for v in obj]
+        if isinstance(obj, BaseModel | BaseModelV1):
+            if hasattr(obj, "model_dump"):
+                obj_dict = obj.model_dump()
+            elif hasattr(obj, "dict"):
+                obj_dict = obj.dict()
+            return {k: recursive_serialize_or_str(v) for k, v in obj_dict.items()}
+
+        if isinstance(obj, AsyncIterator | Generator | Iterator):
+            # contain memory addresses
+            # without consuming the iterator
+            # return list(obj) consumes the iterator
+            # return f"{obj}" this generates '<generator object BaseChatModel.stream at 0x33e9ec770>'
+            # it is not useful
+            return "Unconsumed Stream"
+        if hasattr(obj, "dict"):
+            return {k: recursive_serialize_or_str(v) for k, v in obj.dict().items()}
+        if hasattr(obj, "model_dump"):
+            return {k: recursive_serialize_or_str(v) for k, v in obj.model_dump().items()}
+        if isinstance(obj, type) and issubclass(obj, BaseModel):
+            # This a type BaseModel and not an instance of it
+            return repr(obj)
+        return str(obj)
+    except Exception:  # noqa: BLE001
+        logger.debug(f"Cannot serialize object {obj}")
+        return str(obj)