how to call Synchronous function in node js

Question

i have created one global function for fetching records from database mysql , but its return undefined
but once we pass static data under this function its working fine ,

   methods.trendingPodData =   function (){
    var sql = "SELECT * from table1 where 1";
      con.query(sql, function (err, result, fields) {
        var myJSON = JSON.stringify(result);
        var hashtagsArray = JSON.parse(myJSON);
         //console.log(hashtagsArray);
         return hashtagsArray;      
   }); 
}

FYI, this is an asynchronous operation, not a synchronous operation. So, your title is wrong. — jfriend00, May 16 '20 at 16:05

Vikas Keskar · Answer 1 · 2020-05-16T15:48:38.647

0

Create promise and while calling function resolve it,

 methods.trendingPodData = () => {
  return new Promise((resolve, reject) => {
    var sql = "SELECT * from table1 where 1";
      con.query(sql, (err, result, fields) => {
        if(err) {
         return reject(err)
        }
        var myJSON = JSON.stringify(result);
        var hashtagsArray = JSON.parse(myJSON);
         //console.log(hashtagsArray);
         resolve(hashtagsArray);      
   }); 
 }
}

And while calling function,

router.get('/GetPodHomeScreen', async (req, res) => {
 try {
  const allTrendingDataArray1 = await globalVar.data.trendingPodData(); 
  res.send(allTrendingDataArray1)
 } catch(error) {
  res.status(500).send(error)
 }
})

edited May 16 '20 at 15:48

answered May 16 '20 at 15:26

Vikas Keskar

1,158
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17

Can you let me know how to create promise? – Deepak Goud May 16 '20 at 15:28
Please check code from answer – Vikas Keskar May 16 '20 at 15:29
ok i am calling like this – Deepak Goud May 16 '20 at 15:34
AllTrendingDataArray1 = globalVar.data.trendingPodData(); – Deepak Goud May 16 '20 at 15:34
You are familiar with async/await? – Vikas Keskar May 16 '20 at 15:34
No Sir i am not – Deepak Goud May 16 '20 at 15:36
i am new in node js – Deepak Goud May 16 '20 at 15:36
Please check for promisification section in JavaScript – Vikas Keskar May 16 '20 at 15:37
as you modified function there is no return type so how can i got result AllTrendingDataArray1 = globalVar.data.trendingPodData(); – Deepak Goud May 16 '20 at 15:38
Please share function where you are calling, ```AllTrendingDataArray1 = globalVar.data.trendingPodData(); ``` – Vikas Keskar May 16 '20 at 15:39
router.get('/GetPodHomeScreen', function (req, res) { AllTrendingDataArray1 = globalVar.data.trendingPodData(); } – Deepak Goud May 16 '20 at 15:43
i am creating API , here created one function and fetching data for same function as i have shared you already – Deepak Goud May 16 '20 at 15:43
Please check updated answer. – Vikas Keskar May 16 '20 at 15:45
once i have updated , getting this error – Deepak Goud May 16 '20 at 15:47
await is only valid in async function – Deepak Goud May 16 '20 at 15:47
Yes, ```async (req, res) => {``` it has async there – Vikas Keskar May 16 '20 at 15:49
Yes Now working Vikas Sir Thanks – Deepak Goud May 16 '20 at 15:50
Accept it as answer – Deepak Goud May 16 '20 at 15:53

how to call Synchronous function in node js

1 Answers1