From a5ca08844718a162271af9ae6bdd80a0bccf9f1b Mon Sep 17 00:00:00 2001
From: Harrison Chase <hw.chase.17@gmail.com>
Date: Mon, 18 Dec 2023 10:45:13 -0800
Subject: [PATCH] add methods to deserialize prompts that were old

---
 libs/core/langchain_core/load/load.py         |  11 +-
 libs/core/langchain_core/load/mapping.py      | 159 ++++++++++++++++++
 .../unit_tests/runnables/test_history.py      |   3 +-
 3 files changed, 169 insertions(+), 4 deletions(-)

diff --git a/libs/core/langchain_core/load/load.py b/libs/core/langchain_core/load/load.py
index e97deede28bf0..89980bc07436e 100644
--- a/libs/core/langchain_core/load/load.py
+++ b/libs/core/langchain_core/load/load.py
@@ -3,11 +3,16 @@
 import os
 from typing import Any, Dict, List, Optional
 
-from langchain_core.load.mapping import SERIALIZABLE_MAPPING
+from langchain_core.load.mapping import (
+    OLD_PROMPT_TEMPLATE_FORMATS,
+    SERIALIZABLE_MAPPING,
+)
 from langchain_core.load.serializable import Serializable
 
 DEFAULT_NAMESPACES = ["langchain", "langchain_core", "langchain_community"]
 
+ALL_SERIALIZABLE_MAPPINGS = {**SERIALIZABLE_MAPPING, **OLD_PROMPT_TEMPLATE_FORMATS}
+
 
 class Reviver:
     """Reviver for JSON objects."""
@@ -67,13 +72,13 @@ def __call__(self, value: Dict[str, Any]) -> Any:
             if namespace[0] in DEFAULT_NAMESPACES:
                 # Get the importable path
                 key = tuple(namespace + [name])
-                if key not in SERIALIZABLE_MAPPING:
+                if key not in ALL_SERIALIZABLE_MAPPINGS:
                     raise ValueError(
                         "Trying to deserialize something that cannot "
                         "be deserialized in current version of langchain-core: "
                         f"{key}"
                     )
-                import_path = SERIALIZABLE_MAPPING[key]
+                import_path = ALL_SERIALIZABLE_MAPPINGS[key]
                 # Split into module and name
                 import_dir, import_obj = import_path[:-1], import_path[-1]
                 # Import module
diff --git a/libs/core/langchain_core/load/mapping.py b/libs/core/langchain_core/load/mapping.py
index 923525f0fdb9d..dcec6affb406b 100644
--- a/libs/core/langchain_core/load/mapping.py
+++ b/libs/core/langchain_core/load/mapping.py
@@ -476,3 +476,162 @@
         "RunnableRetry",
     ),
 }
+
+# Needed for backwards compatibility for a few versions where we serialized
+# with langchain_core
+OLD_PROMPT_TEMPLATE_FORMATS = {
+    (
+        "langchain_core",
+        "prompts",
+        "base",
+        "BasePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "base",
+        "BasePromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "prompt",
+        "PromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "prompt",
+        "PromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "MessagesPlaceholder",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "MessagesPlaceholder",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "ChatPromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "ChatPromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "HumanMessagePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "HumanMessagePromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "SystemMessagePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "SystemMessagePromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "BaseMessagePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "BaseMessagePromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "BaseChatPromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "BaseChatPromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "ChatMessagePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "ChatMessagePromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "few_shot_with_templates",
+        "FewShotPromptWithTemplates",
+    ): (
+        "langchain_core",
+        "prompts",
+        "few_shot_with_templates",
+        "FewShotPromptWithTemplates",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "pipeline",
+        "PipelinePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "pipeline",
+        "PipelinePromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "string",
+        "StringPromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "string",
+        "StringPromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "BaseStringMessagePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "BaseStringMessagePromptTemplate",
+    ),
+    (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "AIMessagePromptTemplate",
+    ): (
+        "langchain_core",
+        "prompts",
+        "chat",
+        "AIMessagePromptTemplate",
+    ),
+}
diff --git a/libs/core/tests/unit_tests/runnables/test_history.py b/libs/core/tests/unit_tests/runnables/test_history.py
index 193a779021f50..72cfcbf77cdd6 100644
--- a/libs/core/tests/unit_tests/runnables/test_history.py
+++ b/libs/core/tests/unit_tests/runnables/test_history.py
@@ -19,7 +19,8 @@ def test_interfaces() -> None:
 
 
 def _get_get_session_history(
-    *, store: Optional[Dict[str, Any]] = None
+    *,
+    store: Optional[Dict[str, Any]] = None,
 ) -> Callable[..., ChatMessageHistory]:
     chat_history_store = store if store is not None else {}