gistfile1.txt

;; from db
(def coll [{:id 1 :name ""} 
           {:id 2 :name "item 1" :parent 1} 
           {:id 3 :name "item 2" :parent 1}
           {:id 4 :name "item 3" :parent 2}
           {:id 5 :name "item 4" :parent 2}
           {:id 6 :name "item 5" :parent 2}
           {:id 7 :name "item 6" :parent 4}])
          
;; требуемый json
 {id: 1, name: "", child: [{id: 2, name: "item 1", child: [ 
                                                          {id: 4, name: "item 3", child: [] }  
                                                          {id: 5, name: "item 4", child: [] }  
                                                          {id: 6, name: "item 5", child: [] } ]},
                           {id: 3, name: "item 2", child: [ 
                                                          {id: 7, name: "item 6", child: [] }                                                             
                                                          ]}]}
                                                          
;; т.е. необходимо преобразовать coll, чтобы элементы были "вложены" в root-элемент в параметр :child