mogodb and javascript - save all results of find() mongodb in array or in object

Question

I want to save all results of find() mongodb in array:

enter code here
enter code here
var dbOpen = dbHandle.open( function () {
    var resultRead = readObj();
    console.log('resultRead: ', resultRead);

});
var readObj = function ( obj_type, callback ) {
var arr;
if (callback)
    return;
dbHandle.collection('users', function(err, collect){
    collect.find({name: "Tom"}, {_id:0 }).toArray(function (err, result){
        if(err){
            console.log('ERROR:',err);
        } 
        else{
            console.log('result:', result);


            arr = result[0];
            console.log('arr: ', arr) ; 
            return arr;
            callback( result );


            }
        });

     });

   }

But resultRead: undefined. How can save all results of find() mongodb in array or object? Please, help me

Answer 1

You need to understand that mongodb api is async. When you call readObj, it will not return anything immediately. Hence you get undefined.

To solve this you can register a callback to readObj function. Something like:

var dbOpen = dbHandle.open( function () {
    var resultRead = readObj(function(resultRead){
        console.log('resultRead: ', resultRead);
    });
});

var readObj = function ( obj_type, callback ) {
    var arr;
    if (!callback) return;
    dbHandle.collection('users', function(err, collect){
        collect.find({name: "Tom"}, {_id:0 }).toArray(function (err, result){
            if(err){
                console.log('ERROR:',err);
            } else {
              console.log('result:', result);
              arr = result[0];
              console.log('arr: ', arr) ; 
              return callback( arr );
            }
        });
     });
 }