From 76b666c2d2d369741488814d636165f3e765f2e9 Mon Sep 17 00:00:00 2001
From: Francesco Frassinelli <fraph24@gmail.com>
Date: Sun, 24 Sep 2023 21:22:46 +0200
Subject: [PATCH] Handle empty multiple_checkbox

---
 .../templates/scheming/form_snippets/multiple_checkbox.html  | 5 +++++
 ckanext/scheming/validation.py                               | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/ckanext/scheming/templates/scheming/form_snippets/multiple_checkbox.html b/ckanext/scheming/templates/scheming/form_snippets/multiple_checkbox.html
index 0e4b8d13..57758858 100644
--- a/ckanext/scheming/templates/scheming/form_snippets/multiple_checkbox.html
+++ b/ckanext/scheming/templates/scheming/form_snippets/multiple_checkbox.html
@@ -27,6 +27,11 @@
   {%- if field.get('sorted_choices') -%}
     {%- set choices = choices|sort(case_sensitive=false, attribute=1) -%}
   {%- endif -%}
+    <input
+        type="hidden"
+        name="{{ field.field_name }}"
+        value=""
+    />
     <fieldset class="checkboxes">
         {%- for val, label in choices -%}
             <label for="field-{{ field.field_name }}-{{ val }}">
diff --git a/ckanext/scheming/validation.py b/ckanext/scheming/validation.py
index 5450161d..d9c3cb14 100644
--- a/ckanext/scheming/validation.py
+++ b/ckanext/scheming/validation.py
@@ -139,6 +139,8 @@ def validator(key, data, errors, context):
             if element in choice_values:
                 selected.add(element)
                 continue
+            if element == "":
+                continue
             errors[key].append(_('unexpected choice "%s"') % element)
 
         if not errors[key]: