mongodb - Clojure - Monger Operators - missing multiple field concat and query support with Date conversion -

i have data set on mongo like:

{"month": 9, "year": 2015, "name": "mr a"} {"month": 9, "year": 2015, "name": "mr b"} {"month": 10, "year": 2015, "name": "mr b"} {"month": 11, "year": 2016, "name": "mr b"} 

i trying minimum date using monger, without luck.

the best coming distinct month , year using:

(mc/aggregate mongo-connection collection-name [{$group { :_id { :month "$month", :year "$year" } } }])) 

which gave result like:

[{"_id":{"year":2016,"month":11}},  {"_id":{"year":2016,"month":10}},  {"_id":{"year":2016,"month":9}}] 

and using clojure libraries minimum date. there direct way using monger?

to in monger sort result first year ascending, month ascending, pick first result.

here's modified example documentation:

(ns my.service.server   (:refer-clojure :exclude [sort find])   (:require [monger.core :as mg]             [monger.query :refer :all]))  (let [conn (mg/connect)       db   (mg/get-db "your-db")       coll "your-coll"]   (with-collection db coll     (find {})     (fields [:year :month])     ;; important use array maps sort     (sort (array-map :year 1 :month 1))     (limit 1)) 

if often, consider adding index collection speed query:

(ns my.app   (:require [monger.core :as mg]             [monger.collection :as mc]))  (let [conn (mg/connect)       db   (mg/get-db "your-db")       coll "your-collection"]    ;; create index on multiple fields (will automatically named year_1_month_1 convention)   (mc/ensure-index db coll (array-map :year 1 :month 1)))