Node Js callback return function

Question

I want to return database value in node js and pass as a variable in ejs file.

Bellow is the code, Which I used. it did not return value.

function getExternalLocation(cb) {  

    mssql.connect(msSqlSettings, function (err ) { 
        if (err) {
            cb(err);
        }       
        var getQuery = "SELECT [Title] FROM [dbo].[StyleTemplates] " ;
        //console.log(getQuery);
        var request = new mssql.Request();          
        // query to the database and get the data   

        request.query(getQuery, function (err, rows) {
            mssql.close();  
            cb(err, rows);          
        });
    }); 
}

exports.eejsBlock_editbarMenuLeft = function (hook_name, args, cb) {
    var userData = getExternalLocation(args, function(err, rows) {});
    args.content = args.content + eejs.require(
        'ep_resources/templates/editbarButtons.ejs', {
        userData: userData
    });
    return cb();
})

userData did not return any value.

Possible duplicate of How do I return the response from an asynchronous call? — Jonas Wilms
– Jonas Wilms, Commented Jul 1, 2017 at 10:15
Why do you implement a callback if youre not using it?? Small hint rows contains what you want — Jonas Wilms
– Jonas Wilms, Commented Jul 1, 2017 at 10:16
Basically, I want to return database all values which are stored in "Rows" variable. but it is do not return any value when I used to return rows — Sushil Kumar
– Sushil Kumar, Commented Jul 1, 2017 at 10:29

Borkes · Accepted Answer · 2017-07-01 10:55:05Z

1

var userData = getExternalLocation(args, function(err, rows) {});

I don't think userData will get right data in async function, there is no await, so you can try to get data in callback.

getExternalLocation(args, function(err, rows) {
   var userData = rows;
   args.content = args.content + eejs.require(
    'ep_resources/templates/editbarButtons.ejs', {
     userData: userData
   });
});

answered Jul 1, 2017 at 10:55

Borkes

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1 Comment

Borkes Over a year ago

The answer is a sample code of using callback, if you want to use async/await, you need to read ES6 api about promise and async.

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