From c908b0574001c5666a409f99fc4d43a320e35320 Mon Sep 17 00:00:00 2001
From: Philipp Thumfart <philipp@thumfart.eu>
Date: Sat, 14 Mar 2026 17:27:39 +0100
Subject: [PATCH] Added missing logic to reset multi select (#659)

---
 constance/admin.py                            |  6 ++
 constance/static/admin/js/constance.js        | 11 ++++
 .../constance/includes/results_list.html      |  2 +
 tests/test_admin.py                           | 56 +++++++++++++++++++
 4 files changed, 75 insertions(+)

diff --git a/constance/admin.py b/constance/admin.py
index 683c2d2..188f32e 100644
--- a/constance/admin.py
+++ b/constance/admin.py
@@ -1,3 +1,4 @@
+import json
 from collections import OrderedDict
 from datetime import date
 from datetime import datetime
@@ -62,8 +63,13 @@ class ConstanceAdmin(admin.ModelAdmin):
             "is_date": isinstance(default, date),
             "is_datetime": isinstance(default, datetime),
             "is_checkbox": isinstance(form_field.field.widget, forms.CheckboxInput),
+            "is_multi_select": isinstance(
+                form_field.field.widget, (forms.SelectMultiple, forms.CheckboxSelectMultiple)
+            ),
             "is_file": isinstance(form_field.field.widget, forms.FileInput),
         }
+        if config_value["is_multi_select"]:
+            config_value["json_default"] = json.dumps(default if isinstance(default, list) else [default])
         if field_type and field_type in settings.ADDITIONAL_FIELDS:
             serialized_default = form[name].field.prepare_value(default)
             config_value["default"] = serialized_default
diff --git a/constance/static/admin/js/constance.js b/constance/static/admin/js/constance.js
index d828592..1cea255 100644
--- a/constance/static/admin/js/constance.js
+++ b/constance/static/admin/js/constance.js
@@ -12,6 +12,17 @@
 
             if (fieldType === 'checkbox') {
                 field.prop('checked', this.dataset.default === 'true');
+            } else if (fieldType === 'multi-select') {
+                const defaults = JSON.parse(this.dataset.default);
+                const stringDefaults = defaults.map(function(v) { return String(v); });
+                // CheckboxSelectMultiple: individual checkboxes inside a wrapper
+                field.find('input[type="checkbox"]').each(function() {
+                    $(this).prop('checked', stringDefaults.indexOf($(this).val()) !== -1);
+                });
+                // SelectMultiple: <select multiple> element
+                field.find('option').each(function() {
+                    $(this).prop('selected', stringDefaults.indexOf($(this).val()) !== -1);
+                });
             } else if (fieldType === 'date') {
                 const defaultDate = new Date(this.dataset.default * 1000);
                 $('#' + this.dataset.fieldId).val(defaultDate.strftime(get_format('DATE_INPUT_FORMATS')[0]));
diff --git a/constance/templates/admin/constance/includes/results_list.html b/constance/templates/admin/constance/includes/results_list.html
index 1d21f76..b98c739 100644
--- a/constance/templates/admin/constance/includes/results_list.html
+++ b/constance/templates/admin/constance/includes/results_list.html
@@ -31,12 +31,14 @@
                         data-field-id="{{ item.form_field.auto_id }}"
                         data-field-type="{% spaceless %}
                         {% if item.is_checkbox %}checkbox
+                        {% elif item.is_multi_select %}multi-select
                         {% elif item.is_datetime %}datetime
                         {% elif item.is_date %}date
                         {% endif %}
                         {% endspaceless %}"
                         data-default="{% spaceless %}
                         {% if item.is_checkbox %}{% if item.raw_default %} true {% else %} false {% endif %}
+                        {% elif item.is_multi_select %}{{ item.json_default }}
                         {% elif item.is_date %}{{ item.raw_default|date:"U" }}
                         {% elif item.is_datetime %}{{ item.raw_default|date:"U" }}
                         {% else %}{{ item.default }}
diff --git a/tests/test_admin.py b/tests/test_admin.py
index 9eaae37..4f25339 100644
--- a/tests/test_admin.py
+++ b/tests/test_admin.py
@@ -266,6 +266,62 @@ class TestAdmin(TestCase):
         content_str = response.content.decode()
         self.assertGreater(content_str.find("STRING_VALUE"), content_str.find("INT_VALUE"))
 
+    @mock.patch(
+        "constance.settings.ADDITIONAL_FIELDS",
+        {
+            "language_select": [
+                "django.forms.fields.TypedMultipleChoiceField",
+                {
+                    "widget": "django.forms.CheckboxSelectMultiple",
+                    "choices": (("en", "English"), ("de", "German"), ("fr", "French")),
+                    "coerce": str,
+                },
+            ],
+        },
+    )
+    @mock.patch(
+        "constance.settings.CONFIG",
+        {
+            "LANGUAGES": (["en", "de"], "Supported languages", "language_select"),
+        },
+    )
+    def test_reset_to_default_multi_select(self):
+        """
+        Test that multi-select config values render with data-field-type='multi-select'
+        and a JSON-encoded data-default attribute.
+        """
+        # Re-parse additional fields so the mock is picked up by the form
+        from constance.forms import FIELDS
+        from constance.forms import parse_additional_fields
+
+        FIELDS.update(
+            parse_additional_fields(
+                {
+                    "language_select": [
+                        "django.forms.fields.TypedMultipleChoiceField",
+                        {
+                            "widget": "django.forms.CheckboxSelectMultiple",
+                            "choices": (("en", "English"), ("de", "German"), ("fr", "French")),
+                            "coerce": str,
+                        },
+                    ]
+                }
+            )
+        )
+        try:
+            self.client.login(username="admin", password="nimda")
+            request = self.rf.get("/admin/constance/config/")
+            request.user = self.superuser
+            response = self.options.changelist_view(request, {})
+            response.render()
+            content = response.content.decode()
+
+            self.assertIn('data-field-type="multi-select"', content)
+            self.assertIn('data-default="[&quot;en&quot;, &quot;de&quot;]"', content)
+        finally:
+            # Clean up FIELDS to avoid leaking into other tests
+            FIELDS.pop("language_select", None)
+
     def test_labels(self):
         self.assertEqual(type(self.model._meta.label), str)
         self.assertEqual(type(self.model._meta.label_lower), str)