From a62f913a86288999abbf3c68f25b42e8d235d384 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jochen=20Wersd=C3=B6rfer?= <jochen@wersdoerfer.de>
Date: Wed, 2 Aug 2023 17:11:08 +0200
Subject: [PATCH] #98 fixed the "land on last page by default" bug + test

---
 cast/views/audio.py              | 18 +-----------------
 cast/views/video.py              | 16 +---------------
 cast/views/wagtail_pagination.py | 23 +++++++++++++++++++++++
 tests/pagination_test.py         | 14 ++++++++++++++
 4 files changed, 39 insertions(+), 32 deletions(-)
 create mode 100644 cast/views/wagtail_pagination.py

diff --git a/cast/views/audio.py b/cast/views/audio.py
index 06a2d5e8..91a001e8 100644
--- a/cast/views/audio.py
+++ b/cast/views/audio.py
@@ -1,7 +1,5 @@
 from typing import Any
 
-from django.core.paginator import Page, Paginator
-from django.db.models import QuerySet
 from django.http import HttpRequest, HttpResponse
 from django.shortcuts import get_object_or_404, redirect, render
 from django.urls import reverse
@@ -16,21 +14,7 @@
 from ..forms import AudioForm, NonEmptySearchForm
 from ..models import Audio
 from . import AuthenticatedHttpRequest
-
-DEFAULT_PAGE_KEY = "p"
-
-pagination_template = "wagtailadmin/shared/ajax_pagination_nav.html"
-
-
-def paginate(
-    request: HttpRequest,
-    items: QuerySet[Audio],
-    page_key: str = DEFAULT_PAGE_KEY,
-    per_page: int = MENU_ITEM_PAGINATION,
-) -> tuple[Paginator, Page]:
-    paginator: Paginator = Paginator(items, per_page)
-    page = paginator.get_page(request.GET.get(page_key))
-    return paginator, page
+from .wagtail_pagination import paginate, pagination_template
 
 
 @vary_on_headers("X-Requested-With")
diff --git a/cast/views/video.py b/cast/views/video.py
index 10adf2c8..c0709be3 100644
--- a/cast/views/video.py
+++ b/cast/views/video.py
@@ -1,7 +1,5 @@
 from typing import Any
 
-from django.core.paginator import Page, Paginator
-from django.db.models import QuerySet
 from django.http import HttpRequest, HttpResponse
 from django.shortcuts import get_object_or_404, redirect, render
 from django.urls import reverse
@@ -16,19 +14,7 @@
 from ..forms import NonEmptySearchForm, get_video_form
 from ..models import Video
 from . import AuthenticatedHttpRequest
-
-DEFAULT_PAGE_KEY = "p"
-
-
-pagination_template = "wagtailadmin/shared/ajax_pagination_nav.html"
-
-
-def paginate(
-    request: HttpRequest, items: QuerySet[Video], page_key: str = DEFAULT_PAGE_KEY, per_page: int = 20
-) -> tuple[Paginator, Page]:
-    paginator = Paginator(items, per_page)
-    page = paginator.get_page(request.GET.get(page_key, 0))
-    return paginator, page
+from .wagtail_pagination import paginate, pagination_template
 
 
 @vary_on_headers("X-Requested-With")
diff --git a/cast/views/wagtail_pagination.py b/cast/views/wagtail_pagination.py
new file mode 100644
index 00000000..cfda79c3
--- /dev/null
+++ b/cast/views/wagtail_pagination.py
@@ -0,0 +1,23 @@
+from typing import Union
+
+from django.core.paginator import Page, Paginator
+from django.db.models import QuerySet
+from django.http import HttpRequest
+
+from ..appsettings import MENU_ITEM_PAGINATION
+from ..models import Audio, Video
+
+DEFAULT_PAGE_KEY = "p"
+
+pagination_template = "wagtailadmin/shared/ajax_pagination_nav.html"
+
+
+def paginate(
+    request: HttpRequest,
+    items: Union[QuerySet[Audio], QuerySet[Video]],
+    page_key: str = DEFAULT_PAGE_KEY,
+    per_page: int = MENU_ITEM_PAGINATION,
+) -> tuple[Paginator, Page]:
+    paginator: Paginator = Paginator(items, per_page)
+    page = paginator.get_page(request.GET.get(page_key))
+    return paginator, page
diff --git a/tests/pagination_test.py b/tests/pagination_test.py
index 209ba70f..2f5a81f5 100644
--- a/tests/pagination_test.py
+++ b/tests/pagination_test.py
@@ -4,6 +4,7 @@
 from django.shortcuts import render
 
 from cast.models import Blog
+from cast.views.wagtail_pagination import paginate
 
 
 def test_pagination_template_is_not_paginated(simple_request):
@@ -50,3 +51,16 @@ def test_pagination_template_is_paginated_long(simple_request):
 )
 def test_get_other_get_params(query_string, expected_other_get_params):
     assert Blog.get_other_get_params(QueryDict(query_string)) == expected_other_get_params
+
+
+def test_wagtail_admin_pagination_starts_with_first_page(simple_request):
+    """
+    Test that the pagination starts with the first page. There was a bug
+    when the page was fetched like this:
+        page = paginator.get_page(request.GET.get(page_key, 0))
+
+    This would return the last page if there was more than one page. Make
+    sure this does not happen again.
+    """
+    paginator, page = paginate(simple_request, range(100))  # noqa
+    assert page.number == 1