A function to validate a request within the context of compojure application.

validate-request.md

This code was written to validate a very simple map of the structure of {:body {:grepString "grepp" :date "2014-05-03" :environment "nightly"}

This snippet is not idiomatic clojure.

(defn validate-request [req]
  (let [json-vals (:body req)
        grepStr (:grepString json-vals)
        date (:date json-vals)
        env (:environment json-vals)
        errors (atom "")]
    (if (empty? grepStr)
      (swap! errors str "'grepString' must not be null or empty.\n"))
    (if (empty? date)
      (swap! errors str "'date' must not be null or empty.\n"))
    (if (and (not (empty? date)) (invalid-date date))
      (swap! errors str "'date' must be of the form 'YYYY-MM-DD' (i.e. '2016-04-03').\n"))
    (if (empty? env)
      (swap! errors str "'environment' must not be null or empty.\n"))
    (if (not (valid-environment env))
      (swap! errors str "'environment' must be one of the following 'nightly', 'nightly2', 'nightly3' or 'preprod'.\n"))
    (if (not-empty @errors)
      {:body @errors :status 400 :headers {"Content-Type" "text/plain"}}
      {})
    )
  )

If I had more validation to do then looking at one of the validation tools mentioned on http://www.clojure-toolbox.com/ would be a very good way to go. In particular https://github.com/logaan/vlad was mentioned.

A nicer equivalent form is (with thanks to the clojure google groups):

(defn check-values [{{:keys [grepString date environment]} :body}]
  (apply str (cond-> []
                     (empty? grepString) (conj "'grepString' must not be null or empty.\n")
                     (empty? date) (conj "'date' must not be null or empty.\n")
                     (and (not (empty? date)) (invalid-date date)) (conj "'date' must be of the form 'YYYY-MM-DD' (i.e. '2016-04-03').\n")
                     (empty? environment) (conj "'environment' must not be null or empty.\n")
                     (not (valid-environment environment)) (conj "'environment' must be one of the following 'nightly', 'nightly2', 'nightly3' or 'preprod'.\n")
                     )
         )
  )

(defn validate-request [req]
  (let [errors (check-values req)]
    (if (seq errors)  ;;  'seq' is preferred by some over 'empty?'
      {:body errors :status 400 :headers {"Content-Type" "text/plain"}}
      {}
      )
    )
  )