express - Typescript 沒有符合此呼叫的重載

我剛開始接觸 TypeScript，目前遇到困難。我有一個 next.js 和 express 應用程式。

我收到以下錯誤：沒有符合此呼叫的重載。

No overload matches this call.
  The last overload gave the following error.
    Argument of type '(req: Request, res: Response, next: NextFunction) => Promise<Response<any, Record<string, any>> | undefined>' is not assignable to parameter of type 'RequestHandlerParams<ParamsDictionary, any, any, ParsedQs, Record<string, any>>'.
      Type '(req: Request, res: Response, next: NextFunction) => Promise<Response<any, Record<string, any>> | undefined>' is not assignable to type 'RequestHandler<ParamsDictionary, any, any, ParsedQs, Record<string, any>>'.
        Type 'Promise<Response<any, Record<string, any>> | undefined>' is not assignable to type 'void | Promise<void>'.
          Type 'Promise<Response<any, Record<string, any>> | undefined>' is not assignable to type 'Promise<void>'.
            Type 'Response<any, Record<string, any>> | undefined' is not assignable to type 'void'.
              Type 'Response<any, Record<string, any>>' is not assignable to type 'void'.ts(2769)
index.d.ts(203, 5): The last overload is declared here.

我的路由檔案是

import { isAuthenticated } from "../middlewares/isAuthenticated";
const router = express.Router();
router.route("/check-auth").get(isAuthenticated, checkAuth);
export default router;

中介軟體檔案是

import { NextFunction, Request, Response } from "express";

declare global {
    namespace Express{
        interface Request {
            id: string;
        }
    }
}

export const isAuthenticated = async (req: Request, res: Response, next: NextFunction) => 
    {
    try {
        const token = req.cookies.token;
        if (!token) {
            return res.status(401).json({
                success: false,
                message: "User not authenticated"
            });
        }
      
        req.id = decode.userId;
        next();
    } catch (error) {
        return res.status(500).json({
            message: "Internal server error"
        })
    }
}

答案＃1

TypeScript 錯誤發生的原因是 Express 預期中介軟體函數應返回 void 或 Promise<void>。

透過將你的函式設為 async，它會自動回傳一個 Promise，而因為你回傳的是 res.status(...).json(...)（它的型別是 Response），所以函式的回傳型別與 Express 預期的 Promise<void> 不一致。

在 Express 中，中介軟體函數應該要么呼叫 next()，要么結束回應而不返回任何值。要么移除 async，要么確保所有路徑都返回 Promise

已更新 isAuthenticated.ts

export const isAuthenticated = async (req: Request, res: Response, next: NextFunction): Promise<void> => {
    try {
        const token = req.cookies?.token;
        if (!token) {
            res.status(401).json({ success: false, message: "User not authenticated" });
            return; // Exit without returning a Response
        }
        req.id = "exampleUserId"; // Assume this ID is decoded from token
        next();
    } catch (error) {
        res.status(500).json({ message: "Internal server error" });
    }
};