test(General): write test for pydantic serializer, fixed serialization bug

This commit write unit tests for pydantic serializer using cursor ai, and found an issue related to serialization. Originally, the code uses comma to concat string, but map and list also has comma inside. During the deserialization, split using comma will break map and list, leaving `{` with first kv pair for map, and `[` with first element with list. Instead of using concat with comma as separator, I use json to encode the object dict.

amqp/adapter/pydantic_serializer.py

@@ -2,10 +2,12 @@
 This module provides serialization and deserialization functions for Pydantic models that extend BaseModel
 """
 
+import importlib
 import json
 import uuid
 from datetime import datetime
-from typing import Any, Dict
+from types import UnionType
+from typing import Any, Dict, Union, get_args, get_origin
 from urllib.parse import parse_qs, urlparse
 
 from pydantic import BaseModel
@@ -26,8 +28,12 @@ def serialize_object(obj: BaseModel) -> str:
         A string representation of the object.
     """
     class_name = obj.__class__.__name__
+    module_name = obj.__class__.__module__
     obj_dict = {}
-    for key, value in obj.model_dump().items():
+    for key, _ in obj.model_dump().items():
+        # here we use the original value
+        # the one returned by model_dump will convert everything into dict recursively
+        value = getattr(obj, key)
         if isinstance(value, uuid.UUID):
             obj_dict[key] = str(value)
         elif isinstance(value, datetime):
@@ -47,8 +53,21 @@ def serialize_object(obj: BaseModel) -> str:
         else:
             obj_dict[key] = value
 
-    dict_string = ",".join(f"{k}:{v}" for k, v in obj_dict.items())
-    return f"{class_name}:{{{dict_string}}}"
+    dict_string = json.dumps(obj_dict)
+    return f"{module_name}.{class_name}:{dict_string}"
+
+
+def try_deserialize_object(data: str) -> BaseModel | str:
+    """
+    Try deserialize object, if failed, return the input string as-is.
+    """
+    if not isinstance(data, str):
+        return data
+    try:
+        return deserialize_object(data)
+    except Exception as e:
+        logging_debug(f"Failed to deserialize object: {e}")
+        return data
 
 
 def deserialize_object(data: str) -> BaseModel:
@@ -63,93 +82,54 @@ def deserialize_object(data: str) -> BaseModel:
     Returns:
         An R2RSerializable object.
     """
-    class_name, dict_str = data.split(":", 1)
-    dict_str = dict_str.strip("{}")
-    pairs = dict_str.split(",") if dict_str else []
+    class_path, dict_str = data.split(":", 1)
+    module_path, class_name = class_path.rsplit(".", 1)
 
-    obj_dict: Dict[str, Any] = {}
-    for pair in pairs:
-        if not pair or ":" not in pair:
-            continue
-        k, v = pair.split(":", 1)
-        v = v.strip()  # important
-        obj_dict[k] = _convert_value(v)
+    obj_dict: Dict[str, Any] = json.loads(dict_str)
 
-    logging_debug(f"Deserialized object: {class_name}")
+    logging_debug(f"Deserialized object: {class_path}")
     if "[" in class_name:
         class_name = class_name.split("[")[0]
     logging_debug(f"trying object: {class_name}")
-    cls = globals().get(class_name)
+    module = importlib.import_module(module_path)
+    cls = getattr(module, class_name)
     if cls is None:
         raise ValueError(f"Unknown class: {class_name}")
 
+    # process nested model, dict and list
+    for key, value in obj_dict.items():
+        key_type: type[Any] = cls.model_fields[key].annotation
+        # handle union with none, this will give the true type
+        # for example, return `A` if the type is `A | None`
+        if get_origin(key_type) is UnionType or get_origin(key_type) is Union:
+            union_types = get_args(key_type)
+            if len(union_types) > 2:
+                # if there are multiple unions, like `A | B | None`
+                # then we have no way to figure out which one to use
+                raise ValueError(f"Unsupported Union type: {key_type}")
+            # return the none-None one as the type for processing
+            if union_types[0] is type(None):
+                key_type = union_types[1]
+            else:
+                key_type = union_types[0]
+        # skip if the value is None
+        if value is None:
+            continue
+
+        if key_type == uuid.UUID:
+            obj_dict[key] = uuid.UUID(value)
+        elif key_type == datetime:
+            obj_dict[key] = datetime.fromisoformat(value)
+        elif key_type == dict:
+            obj_dict[key] = value
+        elif issubclass(key_type, BaseModel):
+            obj_dict[key] = deserialize_object(value)
+        elif key_type == list:
+            obj_dict[key] = list(map(try_deserialize_object, value))
+
     return cls(**obj_dict)
 
 
-def _convert_value(v: str) -> Any:
-    """
-    Helper function to convert a string to its appropriate Python type.
-    """
-    if v == "None":
-        return None
-    elif _is_uuid_string(v):
-        return uuid.UUID(v)
-    elif _is_datetime_string(v):
-        return datetime.fromisoformat(v)
-    elif _is_int_string(v):
-        return int(v)
-    elif (
-        v.startswith("{")
-        and v.endswith("}")
-        and ":" in v
-        and "{" not in v[1:-1]
-        and "}" not in v[1:-1]
-    ):  # nested object
-        # check if it is a json dict
-        try:
-            json.loads(v)
-            return json.loads(v)
-        except json.JSONDecodeError:
-            return deserialize_object(v)  # recursive call
-    elif v.startswith("[") and v.endswith("]"):  # list
-        v = v[1:-1]  # remove brackets
-        items = v.split(",") if v else []
-        deserialized_list = []
-        for item in items:
-            item = item.strip()
-            deserialized_list.append(_convert_value(item))  # recursive call
-        return deserialized_list
-    else:
-        return v  # Keep as string
-
-
-def _is_uuid_string(s: str) -> bool:
-    """Helper to check if a string is a valid UUID."""
-    try:
-        uuid.UUID(s)
-        return True
-    except ValueError:
-        return False
-
-
-def _is_datetime_string(s: str) -> bool:
-    """Helper to check if a string is a valid datetime in ISO format"""
-    try:
-        datetime.fromisoformat(s)
-        return True
-    except ValueError:
-        return False
-
-
-def _is_int_string(s: str) -> bool:
-    """Helper to check if a string is a valid int."""
-    try:
-        int(s)
-        return True
-    except ValueError:
-        return False
-
-
 def parse_url_query(url):
     """
     Parses a HTTP GET URL and returns (context_path, query_params_dict)