Clojure convert {"a.b" 1, "a.c" 2, "d.e" 3} to {:a {:b 1, :c 2}, :d {:e 3}} (for compojure/hiccup with monger hierarchy)

Question

My mongodb schema has a JSON hierarchy to it. When I get the field params from compojure, the hash is in flat dotted notation like {"a.b" 1, "a.c" 2, "d.e" 3}. I'm wanting to use monger to insert the data, but that expects a real hierarchical format like {:a {:b 1, :c 2}, :d {:e 3}}. Is there any way to automatically convert from one to the other?

Answer 1

Nothing automatic that I know of, but it's pretty straightforward to do the conversion manually:

=> (require 'clojure.string)
=> (defn nest-keys [x]
     (reduce (fn [m [k v]]
               (assoc-in m (map keyword (clojure.string/split k #"\.")) v))
             {}
             x))
=> (nest-keys {"a.b" 1 "a.c" 2 "d.e" 3})
{:d {:e 3}, :a {:c 2, :b 1}}