Use Django messages framework

static/css/style.css

@@ -1346,7 +1346,7 @@ table.metadata td .emoji {
     cursor: pointer;
 }
 
-.announcement.error {
+.message.error {
     background-color: var(--color-bg-error);
 }
 

templates/admin/federation_blocklist.html

@@ -7,13 +7,6 @@
         {% csrf_token %}
         <h1>Import Blocklist</h1>
 
-        {% if bad_format %}
-            <div class="announcement error">Error: The file you uploaded was not a valid blocklist CSV.</div>
-        {% endif %}
-        {% if success %}
-            <div class="announcement">Your blocklist CSV was processed processed with success!</div>
-        {% endif %}
-
         <fieldset>
             {% include "forms/_field.html" with field=form.blocklist %}
         </fieldset>

users/views/admin/federation.py

@@ -1,6 +1,7 @@
 import csv
 
 from django import forms
+from django.contrib import messages
 from django.core.validators import FileExtensionValidator, ValidationError
 from django.db import models
 from django.shortcuts import get_object_or_404, redirect
@@ -87,6 +88,8 @@ class FederationEdit(FormView):
 class FederationBlocklist(FormView):
     template_name = "admin/federation_blocklist.html"
     extra_context = {"section": "federation"}
+    error_msg = "The uploaded file has an invalid blocklist CSV format."
+    success_msg = "The blocklist CSV was processed processed with success!"
 
     class form_class(forms.Form):
         blocklist = forms.FileField(
@@ -121,18 +124,19 @@ class FederationBlocklist(FormView):
 
                 domains.append(domain)
         except (TypeError, ValueError):
-            return redirect(".?bad_format=true")
+            messages.error(self.request, self.error_msg)
+            return redirect(".")
 
         if not domains:
-            return redirect(".?bad_format=true")
+            messages.error(self.request, self.error_msg)
+            return redirect(".")
 
         DomainService.block(domains)
 
-        return redirect(".?success=true")
+        messages.success(self.request, self.success_msg)
+        return redirect("admin_federation")
 
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
         context["page"] = self.request.GET.get("page")
-        context["bad_format"] = self.request.GET.get("bad_format")
-        context["success"] = self.request.GET.get("success")
         return context