From d21d4bda836aecb3653ec8589d643549ba9de68a Mon Sep 17 00:00:00 2001
From: Danielle McLean <dani@00dani.me>
Date: Sun, 19 May 2024 15:59:43 +1000
Subject: [PATCH] Paginate without errors if a page doesn't exist

---
 entries/pagination.py                    | 45 +++++++++++-------------
 lemoncurry/jinja2/lemoncurry/layout.html | 16 ++++-----
 2 files changed, 29 insertions(+), 32 deletions(-)

diff --git a/entries/pagination.py b/entries/pagination.py
index aa7c174..67d1897 100644
--- a/entries/pagination.py
+++ b/entries/pagination.py
@@ -1,35 +1,32 @@
-from django.core.paginator import Paginator
+from typing import Callable
+
+from django.core.paginator import Page, Paginator
 from django.shortcuts import redirect
 
 from lemoncurry.middleware import ResponseException
 
 
-def paginate(queryset, reverse, page):
-    class Page:
-        def __init__(self, i):
-            self.i = i
+def paginate(queryset, reverse: Callable[[int], str], page: int | None) -> Page:
+    def redirect_to_page(i: int):
+        raise ResponseException(redirect(reverse(i)))
 
-        @property
-        def url(self):
-            return reverse(self.i)
-
-        @property
-        def current(self):
-            return self.i == entries.number
-
-    # If the first page was requested, redirect to the clean version of the URL
-    # with no page suffix.
-    if page == 1:
-        raise ResponseException(redirect(Page(1).url))
+    def reversible(p: Page) -> Page:
+        p.reverse = reverse
+        return p
 
     paginator = Paginator(queryset, 10)
-    entries = paginator.page(page or 1)
 
-    entries.pages = tuple(Page(i) for i in paginator.page_range)
+    # If no page number was specified, return page one.
+    if page is None:
+        return reversible(paginator.page(1))
 
-    if entries.has_previous():
-        entries.prev = Page(entries.previous_page_number())
-    if entries.has_next():
-        entries.next = Page(entries.next_page_number())
+    # If the first page was explicitly requested, or the page number was negative, redirect to page one with no URL suffix.
+    if page <= 1:
+        redirect_to_page(1)
 
-    return entries
+    # If the page requested is larger than the last page, then redirect to the last page.
+    if page > paginator.num_pages:
+        redirect_to_page(paginator.num_pages)
+
+    # Just return the current page! Hooray!
+    return reversible(paginator.page(page))
diff --git a/lemoncurry/jinja2/lemoncurry/layout.html b/lemoncurry/jinja2/lemoncurry/layout.html
index 22308c3..322c461 100644
--- a/lemoncurry/jinja2/lemoncurry/layout.html
+++ b/lemoncurry/jinja2/lemoncurry/layout.html
@@ -110,29 +110,29 @@
 
       <nav>
         <ul class="pagination">
-          {% if entries.prev %}
+          {% if entries.has_previous() %}
           <li class="page-item">
-            <a class="page-link" rel="prev" href="{{ entries.prev.url }}">
+            <a class="page-link" rel="prev" href="{{ entries.reverse(entries.previous_page_number()) }}">
               <i class="fas fa-step-backward" aria-hidden="true"></i> <span class="sr-only">previous page</span>
             </a>
           </li>
 
           {% endif %}
-          {% for page in entries.pages %}
-          {% if page.current %}
+          {% for i in entries.paginator.page_range %}
+          {% if i == entries.number %}
           <li class="page-item active">
-            <span class="page-link">{{ page.i }} <span class="sr-only">(current page)</span></span>
+            <span class="page-link">{{ i }} <span class="sr-only">(current page)</span></span>
           </li>
           {% else %}
           <li class="page-item">
-            <a class="page-link" href="{{ page.url }}">{{ page.i }}</a>
+            <a class="page-link" href="{{ entries.reverse(i) }}">{{ i }}</a>
           </li>
           {% endif %}
           {% endfor %}
-          {% if entries.next %}
+          {% if entries.has_next() %}
 
           <li class="page-item">
-            <a class="page-link" rel="next" href="{{ entries.next.url }}">
+            <a class="page-link" rel="next" href="{{ entries.reverse(entries.next_page_number()) }}">
               <i class="fas fa-step-forward" aria-hidden="true"></i> <span class="sr-only">next page</span>
             </a>
           </li>