anthropic: less pydantic for client (#28823)

libs/partners/anthropic/langchain_anthropic/chat_models.py

@@ -1,6 +1,7 @@
 import copy
 import re
 import warnings
+from functools import cached_property
 from operator import itemgetter
 from typing import (
     Any,
@@ -68,11 +69,10 @@
     BaseModel,
     ConfigDict,
     Field,
-    PrivateAttr,
     SecretStr,
     model_validator,
 )
-from typing_extensions import NotRequired, Self
+from typing_extensions import NotRequired
 
 from langchain_anthropic.output_parsers import extract_tool_calls
 
@@ -541,9 +541,6 @@ class Joke(BaseModel):
         populate_by_name=True,
     )
 
-    _client: anthropic.Client = PrivateAttr(default=None)  # type: ignore[assignment]
-    _async_client: anthropic.AsyncClient = PrivateAttr(default=None)  # type: ignore[assignment]
-
     model: str = Field(alias="model_name")
     """Model name to use."""
 
@@ -661,13 +658,11 @@ def build_extra(cls, values: Dict) -> Any:
         values = _build_model_kwargs(values, all_required_field_names)
         return values
 
-    @model_validator(mode="after")
-    def post_init(self) -> Self:
-        api_key = self.anthropic_api_key.get_secret_value()
-        api_url = self.anthropic_api_url
+    @cached_property
+    def _client_params(self) -> Dict[str, Any]:
         client_params: Dict[str, Any] = {
-            "api_key": api_key,
-            "base_url": api_url,
+            "api_key": self.anthropic_api_key.get_secret_value(),
+            "base_url": self.anthropic_api_url,
             "max_retries": self.max_retries,
             "default_headers": (self.default_headers or None),
         }
@@ -677,9 +672,15 @@ def post_init(self) -> Self:
         if self.default_request_timeout is None or self.default_request_timeout > 0:
             client_params["timeout"] = self.default_request_timeout
 
-        self._client = anthropic.Client(**client_params)
-        self._async_client = anthropic.AsyncClient(**client_params)
-        return self
+        return client_params
+
+    @cached_property
+    def _client(self) -> anthropic.Client:
+        return anthropic.Client(**self._client_params)
+
+    @cached_property
+    def _async_client(self) -> anthropic.AsyncClient:
+        return anthropic.AsyncClient(**self._client_params)
 
     def _get_request_payload(
         self,