flow.rule should provide callback support

[bthibault]

I believe that is the issue here:

 // define the rule
    flow.rule("RULE", criteriaArray,
      function(facts) {
         _self = this;
         // do some fact modification asynchronously 
         ruleAction.run(facts.p, rg.then.params, function(err, results) {
                // alert the engine the rule has been modified
                _self.modify(facts.p); 
                _self.retract(facts.p); 
         });
  });

So whats happening here, is the async function ruleAction.run is run, BUT the rule has already fired, which moves the pointer on the linked list then we try to call _self.modify but the fact has already been unlinked.

So we have an async call, with no way to do a callback.

[bthibault]

admittedly i'm a node / js n00b so there could be another for me to structure it.

[doug-martin]

Try this

 // define the rule
    flow.rule("RULE", criteriaArray,
      function(facts, engine, next) {
         _self = this;
         // do some fact modification asynchronously 
         ruleAction.run(facts.p, rg.then.params, function(err, results) {
                if(err){
                    next(err);
                }else{
                // alert the engine the rule has been modified
                _self.modify(facts.p); 
                _self.retract(facts.p); 
                next();
               }
         });
  });

[doug-martin]

I should also note if you are using the DSL then you can just use next. See the action section for a detailed explanation. I'll also update the readme to have a section dedicated about asynchronous actions in nools, since this isn't the first time some one has brought this up.

[bthibault]

hey hey. it worked.

Thanks