In my reduce function, I can only increment a counter with

result.counter += value.counter

These alternatives do not work:

result.counter++
result.counter += 1
result.counter = result.counter + 1

Full code:

def total (query = nil)
map_fn = "function() {
values = {};
values.displays = 1;
values.attempts = this.disposition != '16' ? 1 : 0;
values.contacts = this.disposition == '1' ? 1 : 0;
emit(1,values);
}"

reduce_fn = "function(key, values) {
var total =

{displays: 0, attempts: 0, contacts: 0}

;
values.forEach( function(value)

{ // total.displays++; // FAIL // total.displays += 1; // FAIL // total.displays = total.displays+1; // FAIL total.displays += value.displays; // SUCCESS total.attempts += value.attempts; total.contacts += value.contacts; }

);
return total;
}"

results_collection = Contact.collection.map_reduce(map_fn, reduce_fn, {:out => {:inline => 1}, :raw => true, :query => query})['results']
results_collection.present? ? results_collection.first['value'] : []

end