How to send conditional response with ExpressJS?

Asked Sep 05 '17 at 15:33

Active Sep 05 '17 at 15:42

Viewed 1,317 times

I'm trying to make conditional res.send with if/else statement.

It works. However, after few second my server crash and i got this error

Error: Can't set headers after they are sent.

I update my response so that it's looks like return res.send... But i'm still facing the same issue.

I really need to set my response conditionally and for my app logic i can't set the response outside the if/else. Especially for synchronous purposes.

So how to prevent my server to crash ?

Exemple with firebase :

if(req.body.hasOwnProperty('simplePost')){
      var postRef = admin.database().ref('post')
      postRef.once('value').then((snap)=>{
        if(!snap.exists()){
          return false
        }else{
          postRef.set(data)
          return res.status(200).end()
        }
      })
    }else if(req.body.hasOwnProperty('postWithRedirect')){
      var postRef = admin.database().ref('post')
      postRef.once('value').then((snap)=>{
        if(!snap.exists()){
          return false
        }else{
          postRef.set(data)
          return res.status(200)send({redirectUrl:snap.child('url').val()}).end()
        }
      })
    }

edited Sep 05 '17 at 15:42

asked Sep 05 '17 at 15:33

John doe

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show us the code – CascadiaJS Sep 05 '17 at 15:33
Added some code. sorry – John doe Sep 05 '17 at 15:43
`return` inside a callback returns the callback function, not the surrounding one. – Joe Clay Sep 05 '17 at 15:43
1

Possible duplicate of [How do I return the response from an asynchronous call?](https://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) – Joe Clay Sep 05 '17 at 15:44
Do you have two/more conditional branch that can execute in same flow? From the code shared, I don't see any problem as a response is sent only once for any given condition. – abskmj Sep 05 '17 at 17:17
it's enough to use `return;` after `res.send()` – Amirhossein Mehrvarzi Apr 17 '18 at 16:15

How to send conditional response with ExpressJS?

0 Answers0