Map reduce objects

Transforms a collection into a collection of aggregated groups, by applying a supplied element-mapping function to each element, that transforms each one into a key-value pair, grouping the resulting pairs by key, and finally reducing values in each group applying a suppling 'reduce' function.

Each supplied function is coded in JavaScript.

Note that the correct way of writing those functions may not be obvious; please consult MongoDB documentation for writing them.

See full list.

Additional Information