fix(langchain): Bind schemas for other types of pulled hub prompts (#9057)

Author: jacoblee93

.changeset/silver-dingos-wonder.md

@@ -0,0 +1,5 @@
+---
+"langchain": patch
+---
+
+fix(langchain): Bind schemas for other types of pulled hub prompts

langchain/src/hub/base.ts

@@ -163,17 +163,29 @@ export function bindOutputSchema<T extends Runnable>(loadedSequence: T) {
     "schema" in loadedSequence.first &&
     "last" in loadedSequence &&
     loadedSequence.last !== null &&
-    typeof loadedSequence.last === "object" &&
-    "bound" in loadedSequence.last &&
-    loadedSequence.last.bound !== null &&
-    typeof loadedSequence.last.bound === "object" &&
-    "withStructuredOutput" in loadedSequence.last.bound &&
-    typeof loadedSequence.last.bound.withStructuredOutput === "function"
+    typeof loadedSequence.last === "object"
   ) {
-    // eslint-disable-next-line no-param-reassign
-    loadedSequence.last.bound = loadedSequence.last.bound.withStructuredOutput(
-      loadedSequence.first.schema
-    );
+    if (
+      "bound" in loadedSequence.last &&
+      loadedSequence.last.bound !== null &&
+      typeof loadedSequence.last.bound === "object" &&
+      "withStructuredOutput" in loadedSequence.last.bound &&
+      typeof loadedSequence.last.bound.withStructuredOutput === "function"
+    ) {
+      // eslint-disable-next-line no-param-reassign
+      loadedSequence.last.bound =
+        loadedSequence.last.bound.withStructuredOutput(
+          loadedSequence.first.schema
+        );
+    } else if (
+      "withStructuredOutput" in loadedSequence.last &&
+      typeof loadedSequence.last.withStructuredOutput === "function"
+    ) {
+      // eslint-disable-next-line no-param-reassign
+      loadedSequence.last = loadedSequence.last.withStructuredOutput(
+        loadedSequence.first.schema
+      );
+    }
   }
   return loadedSequence;
 }

langchain/src/hub/tests/hub.int.test.ts

@@ -113,6 +113,18 @@ test("Test LangChain Hub while loading model with dynamic imports and structured
   expect(typeof res.correctness).toBe("boolean");
 });
 
+test("Test LangChain Hub while loading model with dynamic imports and structured output with no binding", async () => {
+  const pulledPrompt = await nodePull("jacob/structured-output-2", {
+    includeModel: true,
+  });
+  const res = await pulledPrompt.invoke({
+    input:
+      "Who is the current president of the USA as of today? You must use the provided tool for the latest info.",
+  });
+  expect(res).not.toBeInstanceOf(AIMessage);
+  expect(typeof res.correctness).toBe("boolean");
+});
+
 test("Test LangChain Hub while loading model not defined in a RunnableBinding", async () => {
   const promptA = await nodePull("hntrl/binding-manifest", {
     includeModel: true,