Input form parameters validation example

params-validation.clj

(defn validate-first_name [params]
  (if-let [nm (-> params :first_name str s/trim norm-first_name)]
    {:first_name nm}
    {::err "wrong first_name" :fld :first_name}))
;

(defn validate-last_name [params]
  (if-let [nm (-> params :last_name str s/trim norm-last_name)]
    {:last_name nm}
    {::err "wrong last_name" :fld :last_name}))
;

(defn validate-town [params]
  (let [town (-> params :town str s/trim)]
    (if (re-matches #"(?i)[a-z0-9\-\.\,\ ]{2,60}" town)
      {:town (cap-first town)}
      {::err "wrong town" :fld :town})))
;


(defn handler [params]
  (let [data
        (reduce
          (fn [data validator]
            (let [res (validator params)]
              ;; stop on ::err or collect validated params
              (if (::err res)
                (reduced res)
                (into data res))))
          {}
          [ validate-first_name
            validate-last_name
            validate-town])]
    ;
    (if-let [errmsg (::err data)]
      (error-response {:err :param :fld (:fld data) :msg errmsg})
      (process-valid-data data)
      ;
;