refactor(langchain): resolve pydantic deprecation warnings (#33125)

Author: mdrxy

libs/langchain/langchain/chains/openai_functions/citation_fuzzy_match.py

@@ -135,10 +135,7 @@ def create_citation_fuzzy_match_chain(llm: BaseLanguageModel) -> LLMChain:
         Chain (LLMChain) that can be used to answer questions with citations.
     """
     output_parser = PydanticOutputFunctionsParser(pydantic_schema=QuestionAnswer)
-    if hasattr(QuestionAnswer, "model_json_schema"):
-        schema = QuestionAnswer.model_json_schema()
-    else:
-        schema = QuestionAnswer.schema()
+    schema = QuestionAnswer.model_json_schema()
     function = {
         "name": schema["title"],
         "description": schema["description"],

libs/langchain/langchain/chains/openai_functions/qa_with_structure.py

@@ -79,10 +79,7 @@ def create_qa_with_structure_chain(
         )
         raise ValueError(msg)
     if isinstance(schema, type) and is_basemodel_subclass(schema):
-        if hasattr(schema, "model_json_schema"):
-            schema_dict = cast("dict", schema.model_json_schema())
-        else:
-            schema_dict = cast("dict", schema.schema())
+        schema_dict = cast("dict", schema.model_json_schema())
     else:
         schema_dict = cast("dict", schema)
     function = {

libs/langchain/langchain/output_parsers/yaml.py

@@ -34,9 +34,7 @@ def parse(self, text: str) -> T:
             yaml_str = match.group("yaml") if match else text
 
             json_object = yaml.safe_load(yaml_str)
-            if hasattr(self.pydantic_object, "model_validate"):
-                return self.pydantic_object.model_validate(json_object)
-            return self.pydantic_object.parse_obj(json_object)
+            return self.pydantic_object.model_validate(json_object)
 
         except (yaml.YAMLError, ValidationError) as e:
             name = self.pydantic_object.__name__
@@ -46,15 +44,7 @@ def parse(self, text: str) -> T:
     @override
     def get_format_instructions(self) -> str:
         # Copy schema to avoid altering original Pydantic schema.
-        if hasattr(self.pydantic_object, "model_json_schema"):
-            # Pydantic v2
-            schema = dict(self.pydantic_object.model_json_schema().items())
-        elif hasattr(self.pydantic_object, "schema"):
-            # Pydantic v1
-            schema = dict(self.pydantic_object.schema().items())
-        else:
-            msg = "Pydantic object must have either model_json_schema or schema method"
-            raise ValueError(msg)
+        schema = dict(self.pydantic_object.model_json_schema().items())
 
         # Remove extraneous fields.
         reduced_schema = schema

libs/langchain/langchain/utils/pydantic.py

@@ -1,3 +1,13 @@
-from langchain_core.utils.pydantic import get_pydantic_major_version
+from langchain_core.utils.pydantic import PYDANTIC_VERSION
+
+
+def get_pydantic_major_version() -> int:
+    """Get the major version of Pydantic.
+
+    Returns:
+        The major version of Pydantic.
+    """
+    return PYDANTIC_VERSION.major
+
 
 __all__ = ["get_pydantic_major_version"]