fix[openai]: add a test, make sure title is propagated to tool_choice (…

…langchain-ai#4921)

libs/langchain-openai/src/chat_models.ts

@@ -1001,8 +1001,9 @@ export class ChatOpenAI<
           openAIFunctionDefinition = schema as FunctionDefinition;
           functionName = schema.name;
         } else {
+          functionName = schema.title ?? functionName;
           openAIFunctionDefinition = {
-            name: schema.title ?? functionName,
+            name: functionName,
             description: schema.description ?? "",
             parameters: schema,
           };

libs/langchain-openai/src/tests/chat_models_structured_output.int.test.ts

@@ -172,6 +172,46 @@ Respond with a JSON object containing three keys:
   expect("number2" in result).toBe(true);
 });
 
+test("withStructuredOutput JSON schema", async () => {
+  const model = new ChatOpenAI({
+    temperature: 0,
+    modelName: "gpt-4-turbo-preview",
+  });
+
+  const jsonSchema = {
+    title: "calculator",
+    description: "A simple calculator",
+    type: "object",
+    properties: {
+      operation: {
+        type: "string",
+        enum: ["add", "subtract", "multiply", "divide"],
+      },
+      number1: { type: "number" },
+      number2: { type: "number" },
+    },
+  };
+  const modelWithStructuredOutput = model.withStructuredOutput(jsonSchema);
+
+  const prompt = ChatPromptTemplate.fromMessages([
+    "system",
+    `You are VERY bad at math and must always use a calculator.
+Respond with a JSON object containing three keys:
+'operation': the type of operation to execute, either 'add', 'subtract', 'multiply' or 'divide',
+'number1': the first number to operate on,
+'number2': the second number to operate on.
+`,
+    "human",
+    "Please help me!! What is 2 + 2?",
+  ]);
+  const chain = prompt.pipe(modelWithStructuredOutput);
+  const result = await chain.invoke({});
+  console.log(result);
+  expect("operation" in result).toBe(true);
+  expect("number1" in result).toBe(true);
+  expect("number2" in result).toBe(true);
+});
+
 test("withStructuredOutput includeRaw true", async () => {
   const model = new ChatOpenAI({
     temperature: 0,