Why Not a Function #6: assoc-non-empty-in

(defn assoc-non-empty-in
  [m ks v]
  (if (or (nil? v) (= v ""))
    (let [ret (dissoc-in m ks)]
      (if (= (get-in ret (butlast ks)) {})
        (dissoc-in ret (butlast ks))
        ret))
    (assoc-in m ks v)))

assoc-non-empty-in is different from assoc-in because it will dissoc a key if the value is a nil or if it is an empty string. In addition to this, if the resulting parent map is empty, it will dissoc it as well. It does not dissoc further parent maps.

(assoc-non-empty-in {} [:room :lights :color] "white")
=> {:room {:lights {:color "white"}}}

(assoc-non-empty-in *1 [:room :lights :color] "")
=> {:room {}}

Written on March 18, 2020