How to concatenate (or union) the results of find() from two mongodb collections in Meteor JS?

- QUESTION -

How can I concatenate (or merge or union) the results of find() from two mongodb collections in Meteor JS? I preferably want to join them as a single cursor object, but fetching and converting to array would be acceptable. What should I use instead of UNION in the following code? Note: I don't need to remove repeated elements. A concatenation is enough.

allLocations: function(){
   location_set_1 = TableA.find({'loc':{$exists:1}},{loc:1,limit:300});
   location_set_2 = TableB.find({'loc':{$exists:1}},{loc:1,limit:300});
   combined_location_set = ??UNION??(location_set_1,location_set_2)
   return combined_location_set;
}

A (n incomplete) solution may be the following but it will return an array. Instead I need to return a cursor object to the "helper" in Meteor:

a=TableA.find()
b=TableB.find()
c=_.extend({},a.fetch(),b.fetch())
// c=[].concat(a.fetch()).concat(b.fetch());
return c;

- ANSWER -




allLocations: function(){
   var location_set_1 = TableA.find({'loc':{$exists:1}},{loc:1,limit:300}).fetch();
   var location_set_2 = TableB.find({'loc':{$exists:1}},{loc:1,limit:300}).fetch();
   var result = [];
   for (i = location_set_1.length - 1; i >= 0; i --) {
       result.push(location_set_1[i]);
   }
   for (i = location_set_2.length - 1; i >= 0; i --) {
       result.push(location_set_2[i]);
   }
   return result;
}