From 8e45362a510236f46f97b6c275b2b8014678f77d Mon Sep 17 00:00:00 2001
From: Matthias Andreas Benkard <code@mail.matthias.benkard.de>
Date: Sun, 14 May 2017 17:08:16 +0200
Subject: Format NILs as empty strings.

---
 formatters.lisp    |  8 ++++++--
 json-template.lisp | 16 +++++++++-------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/formatters.lisp b/formatters.lisp
index a16ad93..a183b59 100644
--- a/formatters.lisp
+++ b/formatters.lisp
@@ -23,7 +23,9 @@
          (escapee-p (lambda (x) (member x escapees :test #'char=))))
     (lambda (string)
       (unless (stringp string)
-        (setq string (format nil "~A" string)))
+        (typecase string
+          (null (setq string ""))
+          (t    (setq string (format nil "~A" string)))))
       (with-output-to-string (out)
         (loop with position = 0
               for escapee-pos = (position-if escapee-p string :start position)
@@ -38,7 +40,9 @@
 
 (defun escape-for-uri (string)
   (unless (stringp string)
-    (setq string (format nil "~A" string)))
+    (typecase string
+      (null (setq string ""))
+      (t    (setq string (format nil "~A" string)))))
   (with-output-to-string (out)
     (map 'list
          (lambda (char)
diff --git a/json-template.lisp b/json-template.lisp
index 0abd91b..5607004 100644
--- a/json-template.lisp
+++ b/json-template.lisp
@@ -177,13 +177,15 @@
        (write-string (second thing) stream))
       (:variable
        (destructuring-bind (variable formatter) (cdr thing)
-         (let ((value (lookup-context contexts variable)))
-           (format stream "~A"
-                   (if formatter
-                       (funcall (cdr (assoc formatter *template-formatters*
-                                            :test #'equal))
-                                value)
-                       value)))))
+         (let* ((value (lookup-context contexts variable))
+                (formatted-value (if formatter
+                                     (funcall (cdr (assoc formatter *template-formatters*
+                                                          :test #'equal))
+                                              value)
+                                     value)))
+           (typecase formatted-value
+             (null (values))
+             (t (format stream "~A" formatted-value))))))
       (:section
        (destructuring-bind (section branch alternative) (cdr thing)
          (let ((value (lookup-context contexts section)))
-- 
cgit v1.2.3