Lidt tomme tanker

Promises.js

var findAndRemove = function(collection, query){
  var promise = new Promise(), 
      remove = function(err, result){
        var ids = [];
        
        if( err ){
          promise.resolve(err);
          return;
        }

        ids = result.map(function(s){ return s._id;});
        result.remove().then(function(err, res){
          promise.resolve(err, ids);
        });
      };

  collection.find(query).then(remove);     

  return promise;
}

var removeParents(){
  return findAndRemove(Parents, {name: 'asd'});
}

var removeKids(err, parentIds){
  return findAndRemove(Kids, {parentId: {$in: parentIds}});  
}

var removeDogs(err, kidsIds){
  return findAndRemove(Dogs, {kidId: {$in: kidsIds}});
}

removeParents().
then(removeKids).
then(removeDogs);