How to handle empty route parameters in express

Question

Im trying to handle an empty route parameter if a path is not specified , I would like to return a new date if the route param is empty. So far server is responding like this: Cannot GET /api/timestamp/

app.get("/api/timestamp/:date_string", function(req,res){

let dateString=req.params.date_string
 if(!req.params.date_string){
    dateString=new Date()
    res.json({"unix": dateString.getTime(), "utc" : dateString.toUTCString()})
  }  

})

Currently the server is not responding with a json new date as expected, anyone knows how to catch an empty route param?

justin · Accepted Answer · 2020-05-06 20:17:28Z

6

Express uses path-to-regexp, so you can check out that documentation here: https://www.npmjs.com/package/path-to-regexp#optional

You can put question mark at the end of parameters to make them optional parameters, like so .../timestamp/:date_string?

edited May 6, 2020 at 20:17

answered May 6, 2020 at 19:08

justin

3022 silver badges6 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

jfriend00 Over a year ago

Where do you see it documented that a ? at the end of a param makes it optional? I can't find that in the Express doc for parameters.

The Fool Over a year ago

if you ctrl f for regex, its mentioned briefly, not really in the context of optional tough, They may assume we know this because we know regex. So you might have to combine our two answers.

The Fool Over a year ago

so express using path-to-regex and they tell you some more about it npmjs.com/package/path-to-regexp

jfriend00 Over a year ago

It looks like the relevant doc is here.

jfriend00 Over a year ago

Express already uses path-to-regexp. You don't need to specifically use it yourself. I had upvoted your answer, but now you are suggesting the OP has to use an additional package and that is NOT correct. This is built into Express already. It is already an Express feature.

|

Rohit Nishad · Accepted Answer · 2020-05-06 19:32:26Z

3

In your case you simply use:

app.get("/api/timestamp/:date_string?", function(req,res){

let dateString=req.params.date_string
 if(!req.params.date_string){
    dateString=new Date()
  }  
  res.json({"unix": dateString.getTime(), "utc" : dateString.toUTCString()})
})

You can simply check any variable or value exists or not,

if(variable){
   // this condition executed only when the variable has value.
}

if(variable) returns true when the giver variable is not

Undefined
null
NaN

AND

it also has some value

answered May 6, 2020 at 19:32

Rohit Nishad

2,7872 gold badges25 silver badges34 bronze badges

Comments

The Fool · Accepted Answer · 2020-05-06 19:19:48Z

1

You do well in checking if your parameter exists. But you have your response only in that if block. I moved it out of the if block so that you will always send a response. Noy only if req.params.date_string doesn't exist.

Edit: I added furthermore the question mark to indicate that your URL parameter is optional, as pointed out in the answer from justin.

app.get("/api/timestamp/:date_string?", function(req,res){
let dateString=req.params.date_string
 if(!req.params.date_string){
    dateString=new Date()
  }  
  res.json({"unix": dateString.getTime(), "utc" : dateString.toUTCString()})
})

edited May 6, 2020 at 19:19

answered May 6, 2020 at 19:07

The Fool

21.2k7 gold badges76 silver badges123 bronze badges

Collectives™ on Stack Overflow

How to handle empty route parameters in express

3 Answers 3

7 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

7 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related