CODEWITHSUNDEEP
node.jsexpresscallback
9879800
9879800

Reputation: 57

Nodejs + Express + mysql callback issue

I 'm having some trouble understanding the behavior of callbacks . For example, the following code does not work as expected cos callbacks . I tried async library but without obtaining the desired behavior.

module.exports.list = function ( req, res ) {
    model.list( id, idx, function( boo ){
       async.forEachOf( boo, function ( b, k, e ) {
            model.sublist( b.text, function( foo ) {
               b.foo = foo;
            })
       })
       res.json({ data : boo }) //boo dont have foo porperty
    });
};

model.list = execute some big mysql query, and return rows (boo is an array).
model.sublist = same as model.list

Edit Solution: 

module.exports.list = function ( req, res ) {
    model.list( id, idx, function( boo ){
        async.forEachOf( boo, function ( b, k, e ) {
            model.sublist( b.text, function( foo ) {
               b.foo = foo;
               e();
            })
        })
        res.json({ data : boo })
    });
};

Upvotes: 0

Views: 158

Answers (1)

Abhilash Km
Abhilash Km

Reputation: 116

should call response only in 2nd callback. read async documentation

 module.exports.list = function ( req, res ) {
    model.list( id, idx, function( boo ){
       async.forEachOf( boo, function ( b, k, e ) {
            model.sublist( b.text, function( foo ) {
               b.foo = foo;
            });
            e();
       },function(){
           res.json({ data : boo }) //boo dont have foo porperty
       });
    });
 }

Upvotes: 2

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