Allow calling chatgpt models from main OpenAI LLM (langchain-ai#191)

langchain/src/llms/openai.ts

@@ -12,7 +12,8 @@ import { backOff } from "exponential-backoff";
 import fetchAdapter from "../util/axios-fetch-adapter.js";
 import { chunkArray } from "../util/index.js";
 import { BaseLLM } from "./base.js";
-import { LLMResult, LLMCallbackManager } from "./index.js";
+import type { LLMResult, LLMCallbackManager } from "./index.js";
+import { OpenAIChat } from "./openai-chat.js";
 
 interface ModelParams {
   /** Sampling temperature to use */
@@ -141,6 +142,10 @@ export class OpenAI extends BaseLLM implements OpenAIInput {
     },
     configuration?: ConfigurationParameters
   ) {
+    if (fields?.modelName?.startsWith("gpt-3.5-turbo")) {
+      // eslint-disable-next-line no-constructor-return
+      return new OpenAIChat(fields, configuration) as any as OpenAI;
+    }
     super(
       fields?.callbackManager,
       fields?.verbose,

langchain/src/llms/tests/openai.int.test.ts

@@ -1,4 +1,5 @@
 import { test, expect } from "@jest/globals";
+import { OpenAIChat } from "../openai-chat.js";
 import { OpenAI } from "../openai.js";
 
 test("Test OpenAI", async () => {
@@ -7,6 +8,14 @@ test("Test OpenAI", async () => {
   console.log({ res });
 });
 
+test("Test OpenAI with chat model returns OpenAIChat", async () => {
+  const model = new OpenAI({ modelName: "gpt-3.5-turbo" });
+  expect(model).toBeInstanceOf(OpenAIChat);
+  const res = await model.call("Print hello world");
+  console.log({ res });
+  expect(typeof res).toBe("string");
+});
+
 test("Test OpenAI in streaming mode", async () => {
   let nrNewTokens = 0;
   let streamedCompletion = "";

test-exports/package.json

@@ -21,4 +21,4 @@
     "prettier": "^2.8.3",
     "typescript": "^4.9.5"
   }
-}
+}