Dynamically create map using vector

Question

I have a vector ["x" "y" "z"].

I am trying to dynamically create the following:

{:aggs {:bucket-aggregation
        {:terms {:field "x"},
         :aggs {:bucket-aggregation 
                {:terms {:field "y"}, 
                 :aggs {:bucket-aggregation 
                        {:terms {:field "z"}}}}}}}}

I currently have the following but can't figure out how to make it recursive

(defn testing [terms]
  {:aggs {:bucket-aggregation 
           {:terms {:field (nth terms 0)} (testing (pop terms))}}})

Answer 1

Here's one way to solve:

(def my-vec ["x" "y" "z"])

(defn testing [[head & tail]]
  (when head
    {:aggs {:bucket-aggregation (merge {:terms {:field head}}
                                       (testing tail))}}))

(testing my-vec)
;=>
;{:aggs {:bucket-aggregation {:terms {:field "x"},
;                             :aggs {:bucket-aggregation {:terms {:field "y"},
;                                                         :aggs {:bucket-aggregation {:terms {:field "z"}}}}}}}}

This works by destructuring the input into a head element and tail elements, so each call is adding a :field of head and recursing on the tail.

And here's another way to solve using reduce:

(reduce
 (fn [acc elem]
   {:aggs {:bucket-aggregation (merge {:terms {:field elem}} acc)}})
 nil
 (reverse my-vec))

This works by reverseing the input vector and building the map from the inside-out. This reduce approach won't result in a stack overflow for large vectors, but the first solution will.