Cannot get async javascript to work

Question

Cannot get async javascript to work

I'm using node.js, RailwayJS and JugglingDB.

I have a model:

Model.afterInitialize = function() {
  var me = this;
  Sequence.getSequence('forModel', function(sequence) {
    me.serialId = sequence;
  });
  me.title = 'Hello';
}

Once it's all done only the attribute title is set. This isn't surprising but I cannot get it to work. I tried using the async module with no luck.

javascript
node.js
railway.js

Answer 1

added a callback parameter to be able to chain.

Model.afterInitialize = function(then)
{
  then = then || function(me) { };

  var me = this;

  Sequence.getSequence('forModel', function(sequence)
  {
    me.serialId = sequence;
    me.title = 'Hello';

    then.call(null, me);
  });
};

Answer 2

If Sequence.getSequence is asynchronous, the serialId will be set from within the callback, when it is invoked. Since it's asynchronous, that's probably after Model.afterInitialize returns. If you have to perform operations that depend on the serialId being set, fire them from the Sequence.getSequence callback.

Answer 3

Model.afterInitialize is part of an third-party API that I cannot change, so unfortunately there is no way to do this. I was hoping some sort of infinite loop checking for a flag would work but it doesn't and it would be a bodge even if it did work.

I ended up hooking into another method Model.beforeSave = function(callback) {};, which requires a callback.

FYI I was using https://github.com/1602/jugglingdb