How to resolve the Syntax error : await is only valid in async function?

Question

I have written a code to return some data from asynchronous call using promise. While I try to execute I get "Syntax Error await is only valid in async function" and also I get Cannot proxy application requests...Error: connect ECONNREFUSED.

I'm unsure why I get these errors

I have tried using async before the function calls, but it didn't work

var http = require('https');
var httpGet = function(url) {
  return new Promise (function(resolve, reject) {
    http.get(url,function(res) {
      res.setEncoding('utf8');
      var body = ''; 
      res.on('data', function(chunk){ 
        body += chunk;
        console.log("The body is "+ body);
      });
      res.on('end',function(){resolve(body);});
    }).on('error', reject);
  });
};

var body = await httpGet('link');
$.response.setBody(body);

I would want variable body to have the data returned from the httpGet function. Right now I'm getting the above mentioned errors. But without using await, I get the value of body as '{}'.

Please help

Does this answer your question? await is only valid in async function — Serge Stroobandt
– Serge Stroobandt, Commented Mar 25, 2021 at 7:13

Aritra Chakraborty · Accepted Answer · 2019-06-20 12:00:08Z

26

await can only be called in a function marked as async. so, you can make an async IIFE and call the httpGet from there.

(async function(){
    var body = await httpGet('link');
    $.response.setBody(body);
})()

Basically when you use one asynchronous operation, you need to make the entire flow asynchronous as well. So the async keyword kindof uses ES6 generator function and makes it return a promise.

You can check this out if you have confusion.

edited Jun 20, 2019 at 12:00

answered Jun 20, 2019 at 11:54

Aritra Chakraborty

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8 Comments

Arun Elangovan Over a year ago

Thanks it works. But I'm not able to store the data in a global variable. Below is what i tried. var result; (async function(){ result = await httpGet('link'); $.response.setBody(result); })() console.log("The result is "+result);

Arun Elangovan Over a year ago

I get the result as undefined. How to retrieve the data and store in a global variable? Here i'm not able to set the body too. It returns null value

Aritra Chakraborty Over a year ago

You will get the result undefined because the console.log will run just after initating the async function. You cannot use sync and async operations at the same time.

Arun Elangovan Over a year ago

Do you have any idea on how to solve this issue? I'm stuck with this

Aritra Chakraborty Over a year ago

It depends on what you want to do with the data. If you want to show it in ui then make a placeholder page, and after the data is there change the page. Or if you want to use a route to return it as an api response you can do that also.

|

Lance Samaria · Accepted Answer · 2021-10-02 03:06:07Z

1

This is what worked for me.

I initially had:

exports.doSomething = functions.database.ref('/posts/{postId}').onCreate((snapshot, context) => {

    // ... 

    const [response] = await tasksClient.createTask({ parent: queuePath, task });
});

But I added the word async here (before the open parentheses to snapshot) and then the error went away

       // here
.onCreate(async (snapshot, context) => {

So now the code is

exports.doSomething = functions.database.ref('/posts/{postId}').onCreate(async (snapshot, context) => {

    // ... 

    const [response] = await tasksClient.createTask({ parent: queuePath, task });
});

answered Oct 2, 2021 at 3:06

Lance Samaria

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