use correct fragment cache key

ephios/core/forms/events.py

@@ -8,7 +8,6 @@
 from django import forms
 from django.contrib.auth import get_user_model
 from django.contrib.auth.models import Group
-from django.core.cache import cache
 from django.core.exceptions import ValidationError
 from django.db.models import Q
 from django.template.loader import render_to_string
@@ -24,6 +23,7 @@
 from ephios.core.models import Event, EventType, LocalParticipation, Shift, UserProfile
 from ephios.core.signup.methods import enabled_signup_methods, signup_method_from_slug
 from ephios.core.widgets import MultiUserProfileWidget
+from ephios.extra.colors import clear_eventtype_color_css_fragment_cache
 from ephios.extra.crispy import AbortLink
 from ephios.extra.permissions import get_groups_with_perms
 from ephios.extra.widgets import ColorInput, CustomDateInput, CustomTimeInput
@@ -249,7 +249,7 @@ def clean_color(self):
         return self.cleaned_data["color"]
 
     def save(self, commit=True):
-        cache.delete("eventtype_colors_css")
+        clear_eventtype_color_css_fragment_cache()
         return super().save(commit=commit)
 
 

ephios/core/templates/core/event_list.html

@@ -12,7 +12,7 @@
 
 {% block content %}
     <style nonce="{{ request.csp_nonce }}">
-        {% cache 900 "eventtype_colors_css" %}
+        {% cache 900 eventtype_colors_css %}
             {% eventtype_colors %}
         {% endcache %}
     </style>

ephios/core/templates/core/home.html

@@ -21,7 +21,7 @@ <h1 class="page-header">
     </h1>
 
     <style nonce="{{ request.csp_nonce }}">
-        {% cache 900 "eventtype_colors_css" %}
+        {% cache 900 eventtype_colors_css %}
             {% eventtype_colors %}
         {% endcache %}
     </style>

ephios/extra/colors.py

@@ -1,6 +1,9 @@
 # inspired by https://jfelix.info/blog/how-to-make-a-text-color-fit-any-background-color
 from math import sqrt
 
+from django.core.cache import cache
+from django.core.cache.utils import make_template_fragment_key
+
 from ephios.core.models import EventType
 
 
@@ -30,3 +33,8 @@ def get_eventtype_color_style(eventtype: EventType):
     return (
         f".eventtype-{eventtype.pk}-color{{background-color:{eventtype.color};color:{text_color}}}"
     )
+
+
+def clear_eventtype_color_css_fragment_cache():
+    key = make_template_fragment_key("eventtype_colors_css", vary_on=None)
+    cache.delete(key)