Introspect with specifiedBy

[1e16miin]

According to GraphQL Spec October2021

When defining a custom scalar, GraphQL services should provide a [scalar specification URL](https://spec.graphql.org/October2021/#scalar-specification-url) via the @specifiedBy directive or the specifiedByURL introspection field.

In schema

type __Type {
  ...
  # may be non-null for custom SCALAR, otherwise null.
  specifiedByURL: String
}

Example query and result

If your service has a custom scalar called :Email and has defined :specified-by, such as ...

{:scalars {:Email {:parse parser-fn
                   :serialize serialize-fn
                   :specified-by "https://datatracker.ietf.org/doc/html/rfc5322"}}

[namenu]

URL constructor is deprecated since Java20.

(defn valid-url? [s]
  (try
    (let [uri (java.net.URI. s)]
      (.toURL uri)
      true)
    (catch Exception _ false)))