gistfile1.clj

; Thoughts on a query API for clj-record.

(require '[clj-record.query :as q)

(manufacturer/find-records {
  :founded "1910"             ; still just a simple equality
  :grade (q/between 85 95)
  :name (q/in "Ford" "GM")})

; where between and in return functions that know what they're about ... 
; specifically they'd have to return a parameterized SQL condition string
; and one or more value parameters.

; The only challenge is that I have to recognize those guys
; when I go to create sql out of a conditions map.
; My only idea so far is to use (fn? ...) and if true
; let it spit itself out.
; (Note I wouldn't want to use (ifn? ...) there because
; eventually we want to allow serialization of clojure data structures,
; and maps and sets implement IFn.)

; So where currently clj-record.core/to-conditions has something like this:

  (if (nil? value)
    [(conj parameterized-conditions (format "%s IS NULL" (name attribute))) values]
    [(conj parameterized-conditions (format "%s = ?" (name attribute))) (conj values value)]))

; It would change to something like

  (cond
    (nil? value)
      [(conj parameterized-conditions (format "%s IS NULL" (name attribute))) values]
    (fn? value)
      (let [[new-condition new-values] (value attribute)]
        [(conj parameterized-conditions new-condition) (apply conj values new-values)])
    :else
      [(conj parameterized-conditions (format "%s = ?" (name attribute))) (conj values value)]))

; Can you think of any downside to making this the one-and-only reason 
; you can put a function into a conditions map?