Make the form-horizontal-control procedure aware of hidden inputs

Signed-off-by: Christopher Baines <mail@cbaines.net>

guix-data-service/web/view/html.scm

@@ -133,6 +133,16 @@
                            (invalid-query-parameter? val))))
          (show-help-span?
           (or help-text has-error? required?)))
+    (if (string=? type "hidden")
+        `(input (@ (class "form-control")
+                   (id ,input-id)
+                   (type ,type)
+                   (name ,input-name)
+                   ,@(match (assq (string->symbol input-name)
+                                  query-parameters)
+                       (#f '())
+                       ((_key . value)
+                        `((value ,(value->text value)))))))
         `(div
           (@ (class ,(string-append
                       "form-group form-group-lg"
@@ -249,7 +259,7 @@
                          ,@(if help-text
                                (list help-text)
                                '())))
-             '())))))
+                 '()))))))
 
 (define (readme contents)
   (layout