fix malli io link for nils (#27639)

* handle nil directly <-> u/pprint-to-str ignores it

* quick refactor

* pprint-to-str handles `nil`, by returning "nil"

* trim schema and value in malli.io url params

src/metabase/util.clj

@@ -260,10 +260,9 @@
 
      (pprint-to-str 'green some-obj)"
   (^String [x]
-   (when x
-     (with-open [w (java.io.StringWriter.)]
-       (pprint x w)
-       (str w))))
+   (with-open [w (java.io.StringWriter.)]
+     (pprint x w)
+     (str w)))
 
   (^String [color-symb x]
    (colorize color-symb (pprint-to-str x))))

src/metabase/util/malli.clj

@@ -2,6 +2,7 @@
   (:refer-clojure :exclude [defn])
   (:require
    [clojure.core :as core]
+   [clojure.string :as str]
    [malli.core :as mc]
    [malli.destructure]
    [malli.error :as me]
@@ -14,15 +15,18 @@
 
 (core/defn- ->malli-io-link
   ([schema]
-   (->malli-io-link schema (try (mg/generate schema {:seed 1 :size 1})
-                                ;; not all schemas can generate values
-                                (catch Exception _ ::none))))
+   (->malli-io-link schema (try
+                             ;; try to make a sample value
+                             (mg/generate schema {:seed 1 :size 1})
+                             ;; not all schemas can generate values
+                             (catch Exception _ ::none))))
   ([schema value]
-   (let [url-schema (codec/url-encode (u/pprint-to-str (mc/form schema)))
-         url-value (if (= ::none value)
-                     ""
-                     (codec/url-encode (u/pprint-to-str value)))]
-     (str "https://malli.io?schema=" url-schema "&value=" url-value))))
+   (str "https://malli.io?schema="
+        (codec/url-encode (str/trim (u/pprint-to-str (mc/form schema))))
+        "&value="
+        (if (= ::none value)
+          ""
+          (codec/url-encode (str/trim (u/pprint-to-str value)))))))
 
 (core/defn- explain-fn-fail!
   "Used as reporting function to minst/instrument!"