CODEWITHSUNDEEP
javascriptnode.jsasync.js
iLaYa ツ
iLaYa ツ

Reputation: 4017

callback undefined in async.waterfall method

From the below code i'm not getting result1 data. It's undefined. Can somebody help me? 

async.waterfall([
    function(callback) {
        request({
            method: 'GET',
            headers: {
                'Content-Type': 'application/json'
            },
            url: url
        }, function(error, response, body) {
            if (error) {
                callback(error);
            } else {
                var result = JSON.parse(body);
                callback(null, result); //sending to next function
            }
        });
    },
    function(result, callback) {

        async.eachSeries(result, function(item, callback) {
            request({
                method: 'GET',
                headers: {
                    'Content-Type': 'application/json'
                },
                url: url+item.id
            }, function(error, response, body) {
                if (error) {
                    callback(error);
                } else {
                    var result1 = JSON.parse(body);
                    callback(null, result1);
                }
            });
        }, function(err, result1) {
            if (!err) {
                callback(null, result1);
            } else {
                callback(err);
            }
        });
    },
    function(result1, callback) {
      console.log(result1);  // getting undefined
        request({
            method: 'GET',
            headers: {
                'Content-Type': 'application/json'
            },
            url: url
        }, function(error, response, body) {
            if (error) {
                callback(error);
            } else {
                var result2 = JSON.parse(body);
                callback(null, result2);
            }
        });
    }
], function(error, res) {
    console.log(res); // process final result
});

Upvotes: 0

Views: 411

Answers (1)

Oleksandr T.
Oleksandr T.

Reputation: 77482

For eachSeries signature looks like this - callback(err), there is no second parameter, that's why result1 is undefined

If you need get results when loop has finished you need use .mapSeries, like so 

async.mapSeries(result, function(item, callback) {
  request({
    method: 'GET',
    headers: {
      'Content-Type': 'application/json'
    },
    url: url + item.id
  }, function(error, response, body) {
    if (error) {
      callback(error);
    } else {
      var result1 = JSON.parse(body);
      callback(null, result1);
    }
  });
}, function(err, result1) {
  if (!err) {
    callback(null, result1);
  } else {
    callback(err);
  }
});

Upvotes: 2

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