Disallow nullish values

langchain-ai · Oct 12, 2023 · e3f5fd4 · e3f5fd4
1 parent 806060f
commit e3f5fd4
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Showing 3 changed files with 4 additions and 8 deletions.
diff --git a/langchain/src/prompts/chat.ts b/langchain/src/prompts/chat.ts
@@ -186,12 +186,12 @@ export class MessagesPlaceholder<
     return true;
   }
 
-  formatMessages(
+  async formatMessages(
     values: TypedPromptInputValues<RunInput>
   ): Promise<BaseMessage[]> {
     this.validateInputOrThrow(values[this.variableName], this.variableName);
 
-    return Promise.resolve(values[this.variableName] as BaseMessage[]);
+    return values[this.variableName];
   }
 }
 

diff --git a/langchain/src/prompts/tests/chat.test.ts b/langchain/src/prompts/tests/chat.test.ts
@@ -344,5 +344,5 @@ test("Does not throw if null or undefined is passed as input to MessagesPlacehol
     question: "What is the meaning of life?",
   });
 
-  expect(formatted).toHaveLength(4);
+  expect(formatted).toHaveLength(2);
 });
diff --git a/langchain/src/schema/index.ts b/langchain/src/schema/index.ts
@@ -461,11 +461,7 @@ export type BaseMessageLike =
 export function isBaseMessage(
   messageLike?: unknown
 ): messageLike is BaseMessage {
-  return (
-    typeof (messageLike as BaseMessage)?._getType === "function" ||
-    messageLike === null ||
-    messageLike === undefined
-  );
+  return typeof (messageLike as BaseMessage)?._getType === "function";
 }
 
 export function coerceMessageLikeToMessage(