Cache checking if books are on shelve in shelve button snippet

bookwyrm/models/shelf.py

@@ -1,5 +1,6 @@
 """ puttin' books on shelves """
 import re
+from django.core.cache import cache
 from django.core.exceptions import PermissionDenied
 from django.db import models
 from django.utils import timezone
@@ -94,8 +95,15 @@ class ShelfBook(CollectionItemMixin, BookWyrmModel):
     def save(self, *args, **kwargs):
         if not self.user:
             self.user = self.shelf.user
+        if self.id and self.user.local:
+            cache.delete(f"book-on-shelf-{self.book.id}-{self.shelf.id}")
         super().save(*args, **kwargs)
 
+    def delete(self, *args, **kwargs):
+        if self.id and self.user.local:
+            cache.delete(f"book-on-shelf-{self.book.id}-{self.shelf.id}")
+        super().delete(*args, **kwargs)
+
     class Meta:
         """an opinionated constraint!
         you can't put a book on shelf twice"""

bookwyrm/templates/snippets/shelve_button/shelve_button.html

@@ -6,8 +6,9 @@
 {% with book.id|uuid as uuid %}
 {% active_shelf book as active_shelf %}
 {% latest_read_through book request.user as readthrough %}
+{% with active_shelf_book=active_shelf.book %}
 <div class="field has-addons mb-0 has-text-weight-normal" data-shelve-button-book="{{ book.id }}">
-    {% if switch_mode and active_shelf.book != book %}
+    {% if switch_mode and active_shelf_book != book %}
     <div class="control">
         {% include 'snippets/switch_edition_button.html' with edition=book size='is-small' %}
     </div>
@@ -20,16 +21,17 @@
 </div>
 
 {% join "want_to_read" uuid as modal_id %}
-{% include 'snippets/reading_modals/want_to_read_modal.html' with book=active_shelf.book id=modal_id class="" %}
+{% include 'snippets/reading_modals/want_to_read_modal.html' with book=active_shelf_book id=modal_id class="" %}
 
 {% join "start_reading" uuid as modal_id %}
-{% include 'snippets/reading_modals/start_reading_modal.html' with book=active_shelf.book id=modal_id class="" %}
+{% include 'snippets/reading_modals/start_reading_modal.html' with book=active_shelf_book id=modal_id class="" %}
 
 {% join "finish_reading" uuid as modal_id %}
-{% include 'snippets/reading_modals/finish_reading_modal.html' with book=active_shelf.book id=modal_id readthrough=readthrough class="" %}
+{% include 'snippets/reading_modals/finish_reading_modal.html' with book=active_shelf_book id=modal_id readthrough=readthrough class="" %}
 
 {% join "progress_update" uuid as modal_id %}
-{% include 'snippets/reading_modals/progress_update_modal.html' with book=active_shelf.book id=modal_id readthrough=readthrough class="" %}
+{% include 'snippets/reading_modals/progress_update_modal.html' with book=active_shelf_book id=modal_id readthrough=readthrough class="" %}
 
+{% endwith %}
 {% endwith %}
 {% endif %}

bookwyrm/templates/snippets/shelve_button/shelve_button_dropdown_options.html

@@ -38,7 +38,7 @@
             <form name="shelve-{{ uuid }}-{{ shelf.identifier }}" action="/shelve/" method="post" autocomplete="off">
                 {% csrf_token %}
                 <input type="hidden" name="book" value="{{ active_shelf.book.id }}">
-                <button class="button {{ class }}" name="shelf" type="submit" value="{{ shelf.identifier }}" {% if shelf in book.shelf_set.all %} disabled {% endif %}>
+                <button class="button {{ class }}" name="shelf" type="submit" value="{{ shelf.identifier }}" {% if book|is_book_on_shelf:shelf %} disabled {% endif %}>
                     <span>{{ shelf.name }}</span>
                 </button>
             </form>

bookwyrm/templates/snippets/shelve_button/shelve_button_options.html

@@ -45,7 +45,13 @@
         <form name="shelve-{{ uuid }}-{{ shelf.identifier }}" action="/shelve/" method="post">
             {% csrf_token %}
             <input type="hidden" name="book" value="{{ active_shelf.book.id }}">
-            <button class="button {{ class }}" name="shelf" type="submit" value="{{ shelf.identifier }}" {% if shelf in book.shelf_set.all %} disabled {% endif %}>
+            <button
+                class="button {{ class }}"
+                name="shelf"
+                type="submit"
+                value="{{ shelf.identifier }}"
+                {% if book|is_book_on_shelf:shelf %} disabled {% endif %}
+            >
                 <span>{{ shelf.name }}</span>
             </button>
         </form>

bookwyrm/templatetags/bookwyrm_tags.py

@@ -43,6 +43,18 @@ def get_user_rating(book, user):
     return 0
 
 
+@register.filter(name="is_book_on_shelf")
+def get_is_book_on_shelf(book, shelf):
+    """is a book on a shelf"""
+    return cache.get_or_set(
+        f"book-on-shelf-{book.id}-{shelf.id}",
+        lambda b, s: s.books.filter(id=b.id).exists(),
+        book,
+        shelf,
+        timeout=15552000,
+    )
+
+
 @register.filter(name="book_description")
 def get_book_description(book):
     """use the work's text if the book doesn't have it"""

bookwyrm/views/reading.py

@@ -46,9 +46,7 @@ class ReadingStatus(View):
             return HttpResponseBadRequest()
 
         # invalidate related caches
-        cache.delete(
-            f"active_shelf-{request.user.id}-{book_id}",
-        )
+        cache.delete(f"active_shelf-{request.user.id}-{book_id}")
 
         desired_shelf = get_object_or_404(
             models.Shelf, identifier=identifier, user=request.user