fix: pydantic validation

libs/aws/langchain_aws/document_compressors/rerank.py

@@ -32,23 +32,21 @@ class BedrockRerank(BaseDocumentCompressor):
         arbitrary_types_allowed=True,
     )
 
-    @model_validator(mode="after")
-    def initialize_client(self) -> Self:
+    @model_validator(mode="before")
+    @classmethod
+    def initialize_client(cls, values: Dict[str, Any]) -> Any:
         """Initialize the AWS Bedrock client."""
-        if not self.client:
-            session = self._get_session()
-            self.client = session.client(
+        if not values.get("client"):
+            session = (
+                boto3.Session(profile_name=values.get("credentials_profile_name"))
+                if values.get("credentials_profile_name", None)
+                else boto3.Session()
+            )
+            values["client"] = session.client(
                 "bedrock-agent-runtime",
-                region_name=self.region_name
-                )
-        return self
-
-    def _get_session(self):
-        return (
-            boto3.Session(profile_name=self.credentials_profile_name)
-            if self.credentials_profile_name
-            else boto3.Session()
-        )
+                region_name=values.get("region_name"),
+            )
+        return values
 
     def rerank(
         self,

libs/aws/tests/unit_tests/document_compressors/test_rerank.py

@@ -20,7 +20,6 @@ def test_initialize_client(mock_boto_session: MagicMock, reranker: BedrockRerank
     session_instance = MagicMock()
     mock_boto_session.return_value = session_instance
     session_instance.client.return_value = MagicMock()
-    reranker.initialize_client()
     assert reranker.client is not None
 
 @patch("langchain_aws.document_compressors.rerank.BedrockRerank.rerank")