add support for chat engines to express

index.ts

@@ -239,30 +239,32 @@ async function run(): Promise<void> {
     }
   }
 
-  if (!program.engine) {
-    if (ciInfo.isCI) {
-      program.engine = getPrefOrDefault("engine");
-    } else {
-      const { engine } = await prompts(
-        {
-          type: "select",
-          name: "engine",
-          message: "Which chat engine would you like to use?",
-          choices: [
-            { title: "SimpleChatEngine", value: "simple" },
-            { title: "ContextChatEngine", value: "context" },
-          ],
-          initial: 0,
-        },
-        {
-          onCancel: () => {
-            console.error("Exiting.");
-            process.exit(1);
+  if (program.framework === "express" || program.framework === "nextjs") {
+    if (!program.engine) {
+      if (ciInfo.isCI) {
+        program.engine = getPrefOrDefault("engine");
+      } else {
+        const { engine } = await prompts(
+          {
+            type: "select",
+            name: "engine",
+            message: "Which chat engine would you like to use?",
+            choices: [
+              { title: "SimpleChatEngine", value: "simple" },
+              { title: "ContextChatEngine", value: "context" },
+            ],
+            initial: 0,
           },
-        },
-      );
-      program.engine = engine;
-      preferences.engine = engine;
+          {
+            onCancel: () => {
+              console.error("Exiting.");
+              process.exit(1);
+            },
+          },
+        );
+        program.engine = engine;
+        preferences.engine = engine;
+      }
     }
   }
 

templates/index.ts

@@ -56,20 +56,30 @@ export const installTemplate = async ({
   /**
    * Copy the selected chat engine files to the target directory and reference it.
    */
-  console.log("\nUsing chat engine:", engine, "\n");
-  const enginePath = path.join(__dirname, "engines", engine);
-  const engineDestPath = path.join(root, "app", "api", "chat", "engine");
-  await copy("**", engineDestPath, {
-    parents: true,
-    cwd: enginePath,
-  });
-  const routeFile = path.join(engineDestPath, "..", "route.ts");
-  const routeFileContent = await fs.readFile(routeFile, "utf8");
-  const newContent = routeFileContent.replace(
-    /^import { createChatEngine }.*$/m,
-    'import { createChatEngine } from "./engine"\n',
-  );
-  await fs.writeFile(routeFile, newContent);
+  let relativeEngineDestPath;
+  if (framework === "express" || framework === "nextjs") {
+    console.log("\nUsing chat engine:", engine, "\n");
+    const enginePath = path.join(__dirname, "engines", engine);
+    relativeEngineDestPath =
+      framework === "nextjs"
+        ? path.join("app", "api", "chat")
+        : path.join("src", "controllers");
+    await copy("**", path.join(root, relativeEngineDestPath, "engine"), {
+      parents: true,
+      cwd: enginePath,
+    });
+    const routeFile = path.join(
+      root,
+      relativeEngineDestPath,
+      framework === "nextjs" ? "route.ts" : "llm.controller.ts",
+    );
+    const routeFileContent = await fs.readFile(routeFile, "utf8");
+    const newContent = routeFileContent.replace(
+      /^import { createChatEngine }.*$/m,
+      'import { createChatEngine } from "./engine"\n',
+    );
+    await fs.writeFile(routeFile, newContent);
+  }
 
   /**
    * Update the package.json scripts.
@@ -86,11 +96,15 @@ export const installTemplate = async ({
     llamaindex: version,
   };
 
-  if (engine === "context") {
+  if (engine === "context" && relativeEngineDestPath) {
     // add generate script if using context engine
     packageJson.scripts = {
       ...packageJson.scripts,
-      generate: "node ./app/api/chat/engine/generate.mjs",
+      generate: `node ${path.join(
+        relativeEngineDestPath,
+        "engine",
+        "generate.mjs",
+      )}`,
     };
   }
 

templates/simple/express/src/controllers/llm.controller.ts

-import { ChatMessage, OpenAI, SimpleChatEngine } from "llamaindex";
 import { NextFunction, Request, Response } from "express";
+import { ChatMessage, OpenAI } from "llamaindex";
+import { createChatEngine } from "../../../../engines/context";
 
 export const chat = async (req: Request, res: Response, next: NextFunction) => {
-	try {
-		const {
-			message,
-			chatHistory,
-		}: {
-			message: string;
-			chatHistory: ChatMessage[];
-		} = req.body;
-		if (!message || !chatHistory) {
-			return res.status(400).json({
-				error: "message, chatHistory are required in the request body",
-			});
-		}
+  try {
+    const {
+      message,
+      chatHistory,
+    }: {
+      message: string;
+      chatHistory: ChatMessage[];
+    } = req.body;
+    if (!message || !chatHistory) {
+      return res.status(400).json({
+        error: "message, chatHistory are required in the request body",
+      });
+    }
 
-		const llm = new OpenAI({
-			model: "gpt-3.5-turbo",
-		});
+    const llm = new OpenAI({
+      model: "gpt-3.5-turbo",
+    });
 
-		const chatEngine = new SimpleChatEngine({
-			llm,
-		});
+    const chatEngine = await createChatEngine(llm);
 
-		const response = await chatEngine.chat(message, chatHistory);
-		const result: ChatMessage = {
-			role: "assistant",
-			content: response.response,
-		};
+    const response = await chatEngine.chat(message, chatHistory);
+    const result: ChatMessage = {
+      role: "assistant",
+      content: response.response,
+    };
 
-		return res.status(200).json({
-			result,
-		});
-	} catch (error) {
-		console.error("[LlamaIndex]", error);
-		return res.status(500).json({
-			error: (error as Error).message,
-		});
-	}
+    return res.status(200).json({
+      result,
+    });
+  } catch (error) {
+    console.error("[LlamaIndex]", error);
+    return res.status(500).json({
+      error: (error as Error).message,
+    });
+  }
 };