fix(core): serialization patch (#34455)

- `allowed_objects` kwarg in `load`
- escape lc-ser formatted dicts on `dump`
- fix for jinja2

---------

Co-authored-by: Mason Daugherty <github@mdrxy.com>

libs/partners/openai/tests/unit_tests/chat_models/test_base.py

@@ -1360,7 +1360,7 @@ def test_structured_outputs_parser() -> None:
         partial(_oai_structured_outputs_parser, schema=GenerateUsername)
     )
     serialized = dumps(llm_output)
-    deserialized = loads(serialized)
+    deserialized = loads(serialized, allowed_objects=[ChatGeneration, AIMessage])
     assert isinstance(deserialized, ChatGeneration)
     result = output_parser.invoke(cast(AIMessage, deserialized.message))
     assert result == parsed_response

libs/partners/openai/tests/unit_tests/test_load.py

@@ -1,4 +1,7 @@
 from langchain_core.load import dumpd, dumps, load, loads
+from langchain_core.prompts.chat import ChatPromptTemplate, HumanMessagePromptTemplate
+from langchain_core.prompts.prompt import PromptTemplate
+from langchain_core.runnables import RunnableSequence
 
 from langchain_openai import ChatOpenAI, OpenAI
 
@@ -6,7 +9,11 @@ from langchain_openai import ChatOpenAI, OpenAI
 def test_loads_openai_llm() -> None:
     llm = OpenAI(model="davinci", temperature=0.5, openai_api_key="hello", top_p=0.8)  # type: ignore[call-arg]
     llm_string = dumps(llm)
-    llm2 = loads(llm_string, secrets_map={"OPENAI_API_KEY": "hello"})
+    llm2 = loads(
+        llm_string,
+        secrets_map={"OPENAI_API_KEY": "hello"},
+        allowed_objects=[OpenAI],
+    )
 
     assert llm2.dict() == llm.dict()
     llm_string_2 = dumps(llm2)
@@ -17,7 +24,11 @@ def test_loads_openai_llm() -> None:
 def test_load_openai_llm() -> None:
     llm = OpenAI(model="davinci", temperature=0.5, openai_api_key="hello")  # type: ignore[call-arg]
     llm_obj = dumpd(llm)
-    llm2 = load(llm_obj, secrets_map={"OPENAI_API_KEY": "hello"})
+    llm2 = load(
+        llm_obj,
+        secrets_map={"OPENAI_API_KEY": "hello"},
+        allowed_objects=[OpenAI],
+    )
 
     assert llm2.dict() == llm.dict()
     assert dumpd(llm2) == llm_obj
@@ -27,7 +38,11 @@ def test_load_openai_llm() -> None:
 def test_loads_openai_chat() -> None:
     llm = ChatOpenAI(model="gpt-3.5-turbo", temperature=0.5, openai_api_key="hello")  # type: ignore[call-arg]
     llm_string = dumps(llm)
-    llm2 = loads(llm_string, secrets_map={"OPENAI_API_KEY": "hello"})
+    llm2 = loads(
+        llm_string,
+        secrets_map={"OPENAI_API_KEY": "hello"},
+        allowed_objects=[ChatOpenAI],
+    )
 
     assert llm2.dict() == llm.dict()
     llm_string_2 = dumps(llm2)
@@ -38,8 +53,85 @@ def test_loads_openai_chat() -> None:
 def test_load_openai_chat() -> None:
     llm = ChatOpenAI(model="gpt-3.5-turbo", temperature=0.5, openai_api_key="hello")  # type: ignore[call-arg]
     llm_obj = dumpd(llm)
-    llm2 = load(llm_obj, secrets_map={"OPENAI_API_KEY": "hello"})
+    llm2 = load(
+        llm_obj,
+        secrets_map={"OPENAI_API_KEY": "hello"},
+        allowed_objects=[ChatOpenAI],
+    )
 
     assert llm2.dict() == llm.dict()
     assert dumpd(llm2) == llm_obj
     assert isinstance(llm2, ChatOpenAI)
+
+
+def test_loads_runnable_sequence_prompt_model() -> None:
+    """Test serialization/deserialization of a chain:
+
+    `prompt | model (RunnableSequence)`
+    """
+    prompt = ChatPromptTemplate.from_messages([("user", "Hello, {name}!")])
+    model = ChatOpenAI(model="gpt-4o-mini", temperature=0.5, openai_api_key="hello")  # type: ignore[call-arg]
+    chain = prompt | model
+
+    # Verify the chain is a RunnableSequence
+    assert isinstance(chain, RunnableSequence)
+
+    # Serialize
+    chain_string = dumps(chain)
+
+    # Deserialize
+    # (ChatPromptTemplate contains HumanMessagePromptTemplate and PromptTemplate)
+    chain2 = loads(
+        chain_string,
+        secrets_map={"OPENAI_API_KEY": "hello"},
+        allowed_objects=[
+            RunnableSequence,
+            ChatPromptTemplate,
+            HumanMessagePromptTemplate,
+            PromptTemplate,
+            ChatOpenAI,
+        ],
+    )
+
+    # Verify structure
+    assert isinstance(chain2, RunnableSequence)
+    assert isinstance(chain2.first, ChatPromptTemplate)
+    assert isinstance(chain2.last, ChatOpenAI)
+
+    # Verify round-trip serialization
+    assert dumps(chain2) == chain_string
+
+
+def test_load_runnable_sequence_prompt_model() -> None:
+    """Test load() with a chain:
+
+    `prompt | model (RunnableSequence)`.
+    """
+    prompt = ChatPromptTemplate.from_messages([("user", "Tell me about {topic}")])
+    model = ChatOpenAI(model="gpt-4o-mini", temperature=0.7, openai_api_key="hello")  # type: ignore[call-arg]
+    chain = prompt | model
+
+    # Serialize
+    chain_obj = dumpd(chain)
+
+    # Deserialize
+    # (ChatPromptTemplate contains HumanMessagePromptTemplate and PromptTemplate)
+    chain2 = load(
+        chain_obj,
+        secrets_map={"OPENAI_API_KEY": "hello"},
+        allowed_objects=[
+            RunnableSequence,
+            ChatPromptTemplate,
+            HumanMessagePromptTemplate,
+            PromptTemplate,
+            ChatOpenAI,
+        ],
+    )
+
+    # Verify structure
+    assert isinstance(chain2, RunnableSequence)
+    assert isinstance(chain2.first, ChatPromptTemplate)
+    assert isinstance(chain2.last, ChatOpenAI)
+
+    # Verify round-trip serialization
+    assert dumpd(chain2) == chain_obj