Question

91

Exclude route from express middleware

rated 0 times [ 93] [ 2] / answers: 1 / hits: 66571 / 10 Years ago, tue, november 25, 2014, 12:00:00

I have a node app sitting like a firewall/dispatcher in front of other micro services and it uses a middleware chain like below:

...

app.use app_lookup

app.use timestamp_validator

app.use request_body

app.use checksum_validator

app.use rateLimiter

app.use whitelist

app.use proxy

...

However for a particular GET route I want to skip all of them except rateLimiter and proxy. Is their a way to set a filter like a Rails before_filter using :except/:only?

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dusty

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answered 10 Years ago elaine · Accepted Answer

Even though there is no build-in middleware filter system in expressjs, you can achieve this in at least two ways.

First method is to mount all middlewares that you want to skip to a regular expression path than includes a negative lookup:

// Skip all middleware except rateLimiter and proxy when route is /example_route

app.use(//((?!example_route).)*/, app_lookup);

app.use(//((?!example_route).)*/, timestamp_validator);

app.use(//((?!example_route).)*/, request_body);

app.use(//((?!example_route).)*/, checksum_validator);

app.use(rateLimiter);

app.use(//((?!example_route).)*/, whitelist);

app.use(proxy);

Second method, probably more readable and cleaner one, is to wrap your middleware with a small helper function:

var unless = function(path, middleware) {

    return function(req, res, next) {

        if (path === req.path) {

            return next();

        } else {

            return middleware(req, res, next);

        }

    };

};



app.use(unless('/example_route', app_lookup));

app.use(unless('/example_route', timestamp_validator));

app.use(unless('/example_route', request_body));

app.use(unless('/example_route', checksum_validator));

app.use(rateLimiter);

app.use(unless('/example_route', whitelist));

app.use(proxy);

If you need more powerfull route matching than simple path === req.path you can use path-to-regexp module that is used internally by Express.

UPDATE :- In express 4.17 req.path returns only '/', so use req.baseUrl :

var unless = function(path, middleware) {

    return function(req, res, next) {

        if (path === req.baseUrl) {

            return next();

        } else {

            return middleware(req, res, next);

        }

    };

};