Fixed #17159 -- Validated returned number of next|previous_page_number

Thanks mehta.apurva at gmail.com for the report and the initial patch
and neaf for the complete patch.

2 files changed, 20 insertions, 4 deletions

diff --git a/docs/releases/1.5.txt b/docs/releases/1.5.txt
index 6512560b50..3e274b5d98 100644
--- a/docs/releases/1.5.txt
+++ b/docs/releases/1.5.txt
@@ -154,6 +154,16 @@ Unicode parameters (``password``, ``salt`` or ``encoded``). If any of the
 hashing methods need byte strings, you can use the
 :func:`~django.utils.encoding.smart_str` utility to encode the strings.
 
+Validation of previous_page_number and next_page_number
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When using :doc:`object pagination </topics/pagination>`,
+the ``previous_page_number()`` and ``next_page_number()`` methods of the
+:class:`~django.core.paginator.Page` object did not check if the returned
+number was inside the existing page range.
+It does check it now and raises an :exc:`InvalidPage` exception when the number
+is either too low or too high.
+
 Features deprecated in 1.5
 ==========================
 
diff --git a/docs/topics/pagination.txt b/docs/topics/pagination.txt
index 566319ff0a..72560469a8 100644
--- a/docs/topics/pagination.txt
+++ b/docs/topics/pagination.txt
@@ -253,13 +253,19 @@ Methods
 
 .. method:: Page.next_page_number()
 
-    Returns the next page number. Note that this is "dumb" and will return the
-    next page number regardless of whether a subsequent page exists.
+    Returns the next page number.
+
+    .. versionchanged:: 1.5
+
+    Raises :exc:`InvalidPage` if next page doesn't exist.
 
 .. method:: Page.previous_page_number()
 
-    Returns the previous page number. Note that this is "dumb" and will return
-    the previous page number regardless of whether a previous page exists.
+    Returns the previous page number.
+
+    .. versionchanged:: 1.5
+
+    Raises :exc:`InvalidPage` if previous page doesn't exist.
 
 .. method:: Page.start_index()