Convert Clojure schema input to lower case.

Question

I can validate clojure schema inputs as string as shown below.

name :- s/Str, 
place :- s/Str,

How can I write a defschema for Email to use like

email : - s/Email 

which will convert/coerce it to lower case.

Answer 1

I happen to have exactly the one...

(ns myapp.utils.schema
  (:import [org.apache.commons.validator.routines EmailValidator])
  (:require [clojure.string :as str]
            [schema.core :as s]
            [schema.coerce :as sco]))

(def valid-email? "Checks that the value is a valid email string."
  (let [ev (EmailValidator/getInstance)]
    (fn [s]
      (and
        (string? s)
        (.isValid ev, ^String s)
        ))))

(def Email "Email schema type, stricter than schema.core/Str."
  (s/pred valid-email?))

(defn sanitize-email [s]
  (if (string? s)
    (-> s str/lower-case str/trim)
    s))

(defn email-matcher [s]
  (when (= Email s) sanitize-email))


(def matcher
  "The Plumatic matcher used for Plumatic schema coercion in myapp."
  (sco/first-matcher [email-matcher,,,]))

(defn coercer 
  [schema]
  (sco/coercer schema matcher))

;; ...

(ns myapp.customer
  (:require [schema.core :as s]
            [myapp.utils.schema :as sc]))

(def Customer 
  {:customer/email sc/Email 
   :customer/name s/Str})

(def coerce-customer (sc/coercer Customer))

(coerce-customer {:customer/email "[email protected] "
                  :customer/name "Valentin"})
=> {:customer/email "[email protected]"
    :customer/name "Valentin"}