Returning an array of middleware from another middleware in express JS?

Question

I have a route to view the information of a shop. The route looks like

router.param('userId',getUserById)
router.get("/store/:storeName/:userId?",isAuthenticated,getStoreDetail)

Based on the condition I want to send a response. In the route the userId is optional. If the userId is not provided it sends only particular information of the shop as a response. And if the userId is provided then I should authenticate the user and then send all the details of the shop.

So I created a middleware to achieve this.

const isAuthenticated = (req, res, next) => {
    const { user } = req
    if (user) {
        return [
            expressJwt(jwtTokenProperty),
            (err, req, res, next) => {
                if (err) {
                    return res.status(401).json({
                        status: false,
                        error: err.message,
                        isJWTError: true
                    })
                }
                const checker = req.user && req.auth && req.user.id == req.auth.id
                if (!checker) {
                    return res.status(401).json({
                        status: false,
                        error: "Invalid Request"
                    })
                }
                next()
            }
        ]
    } else {
        next()
    }
}

If the userId is not provided then I am getting a response as needed. But if the userId is provided I don't get any response.

Leonhard Printz · Accepted Answer · 2022-02-13 14:11:47Z

2

You forgot to return next().

Edit: You need to return a response rather than array containing a function.

const isAuthenticated = (req, res, next) => {
    const { user } = req
    return user
        ? [expressJwt(jwtTokenProperty), processResponse(req, res, next)]
        : next()
}

const processResponse = (req, res, next) => {
    const checker = req.user && req.auth && req.user.id == req.auth.id
    if (!checker) {
        return res.status(401).json({
            status: false,
            error: "Invalid Request"
        })
    }
    return next()
}

edited Feb 13, 2022 at 14:11

answered Feb 13, 2022 at 9:12

Leonhard Printz

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7 Comments

Gnanavel Over a year ago

It's not working. My question is if there exists a user I should check whether he is a valid user and then send the response

Leonhard Printz Over a year ago

Now that I look at it your code does seem curious. You're returning a middleware? I'm not sure a middleware (which is a function of three parameters) is valid to return.

Gnanavel Over a year ago

I too had the same doubt. But I referred to this question - stackoverflow.com/questions/47572752/….

Leonhard Printz Over a year ago

Oh but they're calling the middleware with arguments, not returning it! That's a difference! I've split it out and updated the example. :)

Gnanavel Over a year ago

when we call processResponse() I am getting err is not defined. If I try to add err parameter to isAuthenticated then in the next middleware I am not able to access req parameter

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