CODEWITHSUNDEEP
node.jsexpress
Laura
Laura

Reputation: 3383

Is it possible to use some sort of 'middleware' after sending the response with express?

The typical middleware in express is used before the request hits the routes, for example there's authentication first, then the code of the specific route is executed, then the response is sent.

I am wondering whether it is possible to have a thing like a middleware after a route is hit.

Say I have five routes that all respond with some json and I wanted to log the sent json everytime one of the routes is hit.
I could go and log manually everytime I send a response in a route, like this:

console.log(data);
res.json(data);

but this seems redundant to me. A better approach could be to wrap that in a function to call in the route, but that would require to pass the response object everytime like this:

/* instead of the above */
send(data, res);

/* and then somewhere else usable for all routes */
function send(data, res) {
    console.log(data);
    res.json(data);
}

this also seems a bit like bad practice to me, so I'm wondering whether this would be the preferred way or if there's a way to use some kind of 'middleware', which would allow to send the response in the usual way and hook in after that.

Upvotes: 8

Views: 8066

Answers (1)

Naeem Shaikh
Naeem Shaikh

Reputation: 15725

It is not really possible to attach a middleware which executes after the route, but you can execute a middleware, which binds a finish event on response,

app.use(function(req, res, next){
  res.on('finish', function(){

    // Do whatever you want this will execute when response is finished
  });
  next();
});

also https://stackoverflow.com/a/21858212/3556874

Upvotes: 15

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