Choosing which middleware to run based on request in Express JS

user_8602367 0
Viewed 2138

I would like to know how to choose between two different middleware functions, depending on the request for the endpoint. It could look something like this:

router.post("/findAvailableAgents", middleware1 || middleware2, (req, res) => {
  // endpoint body
})
express node.js javascript
3 Answers

You could use another middleware which decides whether to choose middleware1 or middleware2

const decideMiddleware = (req, res, next) => {
    if(condition) {
        return middleware1(req, res,next)
    } else {
        return middleware2(req, res,next)
    }
}

And use it in your code

router.post("/findAvailableAgents", decideMiddleware, (req, res))
user_97865510

There is two ways of achieve optional middleware behaviour:

1) Create another middleware, that checks condition and then passes all the parameters into the desired middleware. Example:

const middlewareStrategy = (req,res,next) => {
    if(req.body.token1){
        return middleware1(req,res,next);
    }
    return middleware2(req,res,next);
};

router.post("/findAvailableAgents", middlewareStrategy, handler);

2) Make middleware logic execution in a condition-driven manner. Example: 

const middleware1 = (req,res,next) => {
    if(req.body.token){
        // execute some logic, then
        return next();
    }
    // skip this middleware
    next();
};

router.post("/findAvailableAgents", middleware1, middleware2, handler);
user_81258530

Now you can add multiple middleware using a below peice of code

app.get('/',[middleware.requireAuthentication,middleware.logger], function(req, res){
    res.send('Hello!');
});

user_91669740
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