Nodejs best practice encapsulating send middleware

Ok so I am currently learning more node.js and decided to try out some basic middleware in a small api I created. I was wondering how I would wrap a successfull request. This is my approach.

Example Controller

exports.getTask = async function (req, res, next) {
    try {
        const task = await db.Task.findOne(
            {
                where: {
                    id: req.params.taskId,
                    userId: req.params.userId
                }
            });
        if (task) {
            req.locals.data = task;
            res.status(httpStatus.OK);
            next();
        }
        res.status(httpStatus.NOT_FOUND);
        next();
    } catch (err) {
        next(err);
    }
};

Middleware

exports.success = function(req, res, next) {
    const success = res.statusCode < 400;
    const successResponse = {
        timestamp: new Date().toUTCString(),
        success: success,
        status: res.statusCode
    };

    if (success) {
        successResponse.data = req.locals.data;
    }
    res.send(successResponse);
    next();
};

I dont think its very good having to set req.locals.data for every requst and then calling next res.status(status) maybe I just approached the situation the wrong way?

How could you make this better?

Solution

In this case, probably using the express middleware concept (calling next()) will be an overkill.

I'd approach this by creating an abstraction for the success path. Consider something like this:

const resWithSuccess = (req, res, data) => {
    res.json({
      data: data,
      timestamp: new Date().toUTCString(),
      // success: res.statusCode < 400, // --> actually you don't need this,
      //                                       since it will always be true
      // status: res.statusCode // --> or whatever else "meta" info you need
    });
};

Then, as soon as you need to respond with success, go for it:

exports.getTask = async function (req, res, next) {
    // .... bla bla
    if (task) {
        resWithSuccess(tank);
    }
};

PS: ... and you can use the express middleware concept (calling next()) for the error path.