Add a setting to apply limit on number of tags that can be added to any tagged model.

CHANGELOG.txt

@@ -16,6 +16,7 @@ Changelog
  * Renamed `target_model` argument on `PageChooserBlock` to `page_type` (Loic Teixeira)
  * `edit_handler` and `panels` can now be defined on a `ModelAdmin` definition (Thomas Kremmel)
  * Add Learn Wagtail to third-party tutorials in documentation (Matt Westcott)
+ * Add a Django setting `TAG_LIMIT` to limit number of tags that can be added to any taggit model (Mani)
  * Fix: Set `SERVER_PORT` to 443 in `Page.dummy_request()` for HTTPS sites (Sergey Fedoseev)
  * Fix: Include port number in `Host` header of `Page.dummy_request()` (Sergey Fedoseev)
  * Fix: Validation error messages in `InlinePanel` no longer count towards `max_num` when disabling the 'add' button (Todd Dembrey, Thibaud Colas)

docs/advanced_topics/settings.rst

@@ -384,6 +384,15 @@ Multi-word tags
 
 Tags can only consist of a single word, no spaces allowed. The default setting is ``True`` (spaces in tags are allowed).
 
+Tag limit
+---------
+
+.. code-block:: python
+
+  TAG_LIMIT = 5
+
+Limit the number of tags that can be added to (django-taggit) Tag model. Default setting is ``None``, meaning no limit on tags.
+
 Unicode Page Slugs
 ------------------
 

docs/releases/2.5.rst

@@ -26,6 +26,7 @@ Other features
  * Renamed ``target_model`` argument on ``PageChooserBlock`` to ``page_type`` (Loic Teixeira)
  * ``edit_handler`` and ``panels`` can now be defined on a ``ModelAdmin`` definition (Thomas Kremmel)
  * Add Learn Wagtail to third-party tutorials in documentation (Matt Westcott)
+ * Add a Django setting ``TAG_LIMIT`` to limit number of tags that can be added to any taggit model (Mani)
 
 
 Bug fixes

wagtail/admin/static_src/wagtailadmin/js/core.js

@@ -21,7 +21,7 @@ function escapeHtml(text) {
     });
 }
 
-function initTagField(id, autocompleteUrl, allowSpaces) {
+function initTagField(id, autocompleteUrl, allowSpaces, tagLimit) {
     $('#' + id).tagit({
         autocomplete: {source: autocompleteUrl},
         preprocessTag: function(val) {
@@ -34,7 +34,8 @@ function initTagField(id, autocompleteUrl, allowSpaces) {
             return val;
         },
 
-        allowSpaces: allowSpaces
+        allowSpaces: allowSpaces,
+        tagLimit: tagLimit,
     });
 }
 

wagtail/admin/templates/wagtailadmin/widgets/tag_widget.html

@@ -1 +1,9 @@
-{% include 'django/forms/widgets/text.html' %}<script>initTagField('{{ widget.attrs.id|escapejs }}', '{{ widget.autocomplete_url|escapejs }}', {% if widget.tag_spaces_allowed %}true{% else %}false{% endif %});</script>
+{% include 'django/forms/widgets/text.html' %}
+<script>
+    initTagField(
+        '{{ widget.attrs.id|escapejs }}',
+        '{{ widget.autocomplete_url|escapejs }}',
+        {% if widget.tag_spaces_allowed %}true{% else %}false{% endif %},
+        {% if widget.tag_limit %}{{widget.tag_limit}}{% else %}null{% endif %}
+    );
+</script>

wagtail/admin/tests/test_widgets.py

@@ -157,3 +157,58 @@ class TestAdminDateTimeInput(TestCase):
             '"format": "d.m.Y. H:i"',
             html,
         )
+
+
+class TestAdminTagWidget(TestCase):
+
+    def get_js_init_params(self, html):
+        """Returns a list of the params passed in to initTagField from the supplied HTML"""
+        # Eg. ["'test\\u002Did'", "'/admin/tag\\u002Dautocomplete/'", 'true', 'null']
+        start = 'initTagField('
+        end = ');'
+        items_after_init = html.split(start)[1]
+        if items_after_init:
+            params_raw = items_after_init.split(end)[0]
+            if params_raw:
+                return [part.strip() for part in params_raw.split(',')]
+        return []
+
+
+    def test_render_js_init_basic(self):
+        """Chekcs that the 'initTagField' is correctly added to the inline script for tag widgets"""
+        widget = widgets.AdminTagWidget()
+
+        html = widget.render('tags', None, attrs={'id': 'alpha'})
+        params = self.get_js_init_params(html)
+
+        self.assertEqual(len(params), 4)
+        self.assertEqual(params[0], "'alpha'")  # id
+        self.assertEqual(params[1], "'/admin/tag\\u002Dautocomplete/'")  # autocomplete url
+        self.assertEqual(params[2], 'true')  # tag_spaces_allowed
+        self.assertEqual(params[3], 'null')  # tag_limit
+
+
+    @override_settings(TAG_SPACES_ALLOWED=False)
+    def test_render_js_init_no_spaces_allowed(self):
+        """Chekcs that the 'initTagField' includes the correct value based on TAG_SPACES_ALLOWED in settings"""
+        widget = widgets.AdminTagWidget()
+
+        html = widget.render('tags', None, attrs={'id': 'alpha'})
+        params = self.get_js_init_params(html)
+
+        self.assertEqual(len(params), 4)
+        self.assertEqual(params[2], 'false')  # tag_spaces_allowed
+        self.assertEqual(params[3], 'null')  # tag_limit
+
+
+    @override_settings(TAG_LIMIT=5)
+    def test_render_js_init_with_tag_limit(self):
+        """Chekcs that the 'initTagField' includes the correct value based on TAG_LIMIT in settings"""
+        widget = widgets.AdminTagWidget()
+
+        html = widget.render('tags', None, attrs={'id': 'alpha'})
+        params = self.get_js_init_params(html)
+
+        self.assertEqual(len(params), 4)
+        self.assertEqual(params[2], 'true')  # tag_spaces_allowed
+        self.assertEqual(params[3], '5')  # tag_limit

wagtail/admin/widgets.py

@@ -101,6 +101,7 @@ class AdminTagWidget(TagWidget):
         context = super().get_context(name, value, attrs)
         context['widget']['autocomplete_url'] = reverse('wagtailadmin_tag_autocomplete')
         context['widget']['tag_spaces_allowed'] = getattr(settings, 'TAG_SPACES_ALLOWED', True)
+        context['widget']['tag_limit'] = getattr(settings, 'TAG_LIMIT', None)
 
         return context