How to call async.each in an external function having async.waterfall inside async.each

Question

I have a exports module in Node.JS

exports.doSomethingImportant= function(req, res) {
var id = req.params.id;
Demo.findOne({'_id': id})
  .exec(function(err, demosReturned) {
    async.waterfall([
        function(outerCallBack){
          console.log("In the First Call Back");
          firstOrderFunction(demosReturned,outerCallBack);
        },
        function(x,outerCallBack){
           var y =3 
           var z = x*y;
           console.log("In the Second Call Back");
           outerCallBack(null,z);
        }
      ],function(err,z){
        if(err){
          console.log("Error is == " +err);
        }else{
          console.log("The Returned Value is == "+z);
        }
      });
});//End Demo.findOne
};

Now, my firstOrderfunction again has a async.each embedding async.waterfall

function fistOrderFunction(demosReturned,outerCallBack){
console.log("Called the External Function");


async.each(demosReturned.locations, function(location, innerCallBack) {
  console.log('Computing Location #');

    async.waterfall([
          function(internalCallBack){
             console.log("Computing Inner First Waterfall");
               a = 14;
              innternalCallBack(null,a);
          },
          function(a,internalCallBack){
              console.log("Computing Inner Second Waterfall");
               b =14;
               c = a*b;
              innternalBack(null,c)
          }
      ],function(err,c){
        if(err){
          console.log("Error is == " +err);
        }else{
             d = c;
             console.log("The Returned Value is == "+c);
             innerCallBack(null,d);
        }
    });//End Async.Waterfall
},function(err,d){
    if(err){enter code here
      console.log("The Error in Async.Each === " + err);
    }else{
      console.log("The Returned Value is Processed ");
      outerCallBack(null, d);
    }
}); //End Async.Each
}

The Output I get is

---

In the First Call Back

Called the External Function

Computing Location #

Computing Location #

Computing Inner First Waterfall

Computing Inner First Waterfall

The Returned Value is Processed

In the Second Call Back

The Returned Value is == NaN

I want everything to be run synchronously in the following order.

1. Call async.waterfall in exec call back of Demo.findone

2. Call the firstOrderFunction

3. Call async.each inside firstOrderFunction

4. Call async.waterfall inside async.each

5. Call the first callback function returning a=14.

6. Call the second callback function returning c =14*14 =196.

How do I achieve this using async?

Thanks in advance and apology for such a long question.

Answer 1

Call async.each()'s callback at the end of async.waterfall() and call firstOrderFunction's callback at the end of async.each(). Here is the revised code:

function fistOrderFunction(demosReturned, callback){
  var ret = [];

  console.log("Called the External Function");
  async.each(demosReturned.locations, function(location, eachCb) {
    console.log('Computing Location #');

    async.waterfall([
        function(waterfallCb){
            console.log("Computing Inner First Waterfall");
            a = 14;
            waterfallCb(null,a);
        },
        function(a,waterfallCb){
            console.log("Computing Inner Second Waterfall");
            b =14;
            c = a*b;
            waterfallCb(null,c)
        }
    ],function(err,c){
        if(err){
            console.log("Error is == " +err);
            eachCb(err);
        }else{
            ret.push(c);
            console.log("The Returned Value is == "+c);
            eachCb(null);
        }
    });//End Async.Waterfall
  },function(err){
    if(err){
        console.log("The Error in Async.Each === " + err);
        callback(err, null);
    }else{
        console.log("The Returned Value is Processed ");
        callback(null, ret);
    }
  }); //End Async.Each
}