From 675d3f38b9a8a3b305b76aff542446e02be6ef28 Mon Sep 17 00:00:00 2001
From: Jake Howard <git@theorangeone.net>
Date: Wed, 20 Jul 2022 08:41:40 +0100
Subject: [PATCH] Ensure tags menu item works when the list page doesn't exist

---
 website/blog/wagtail_hooks.py | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/website/blog/wagtail_hooks.py b/website/blog/wagtail_hooks.py
index 891babb..3baa9dc 100644
--- a/website/blog/wagtail_hooks.py
+++ b/website/blog/wagtail_hooks.py
@@ -1,3 +1,4 @@
+from django.http.request import HttpRequest
 from django.urls import reverse
 from wagtail import hooks
 from wagtail.admin.menu import MenuItem
@@ -5,15 +6,28 @@ from wagtail.admin.menu import MenuItem
 from .models import BlogPostTagListPage
 
 
+class BlogPostTagsMenuItem(MenuItem):
+    url: str
+
+    def __init__(self) -> None:
+        super().__init__("Blog post tags", url="", icon_name="tag")
+
+    def is_shown(self, request: HttpRequest) -> bool:
+        if not self.url:
+            blog_post_tag_list_id = (
+                BlogPostTagListPage.objects.live()  # type:ignore[attr-defined]
+                .values_list("id", flat=True)
+                .first()
+            )
+            self.url = (
+                reverse("wagtailadmin_explore", args=[blog_post_tag_list_id])
+                if blog_post_tag_list_id
+                else ""
+            )
+
+        return bool(self.url)
+
+
 @hooks.register("register_admin_menu_item")
 def register_blog_post_tags_menu_item() -> MenuItem:
-    blog_post_tag_list_id = (
-        BlogPostTagListPage.objects.live()  # type:ignore[attr-defined]
-        .values_list("id", flat=True)
-        .get()
-    )
-    return MenuItem(
-        "Blog post tags",
-        reverse("wagtailadmin_explore", args=[blog_post_tag_list_id]),
-        icon_name="tag",
-    )
+    return BlogPostTagsMenuItem()