Added a new and improved Paginator class, which allows you to pass a Page object to the template instead of 5 or 6 separate variables. ObjectPaginator still exists for backwards compatibility but issues a DeprecationWarning

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7306 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/paginator.py

@@ -1,46 +1,149 @@
 class InvalidPage(Exception):
     pass
 
-class ObjectPaginator(object):
+class Paginator(object):
-    """
+    def __init__(self, object_list, per_page, orphans=0, allow_empty_first_page=True):
-    This class makes pagination easy. Feed it a QuerySet or list, plus the number
+        self.object_list = object_list
-    of objects you want on each page. Then read the hits and pages properties to
+        self.per_page = per_page
-    see how many pages it involves. Call get_page with a page number (starting
+        self.orphans = orphans
-    at 0) to get back a list of objects for that page.
+        self.allow_empty_first_page = allow_empty_first_page
+        self._num_pages = self._count = None
 
-    Finally, check if a page number has a next/prev page using
+    def validate_number(self, number):
-    has_next_page(page_number) and has_previous_page(page_number).
+        "Validates the given 1-based page number."
-    
+        try:
-    Use orphans to avoid small final pages. For example:
+            number = int(number)
-    13 records, num_per_page=10, orphans=2 --> pages==2, len(self.get_page(0))==10
+        except ValueError:
-    12 records, num_per_page=10, orphans=2 --> pages==1, len(self.get_page(0))==12
+            raise InvalidPage('That page number is not an integer')
+        if number < 1:
+            raise InvalidPage('That page number is less than 1')
+        if number > self.num_pages:
+            if number == 1 and self.allow_empty_first_page:
+                pass
+            else:
+                raise InvalidPage('That page contains no results')
+        return number
+
+    def page(self, number):
+        "Returns a Page object for the given 1-based page number."
+        number = self.validate_number(number)
+        bottom = (number - 1) * self.per_page
+        top = bottom + self.per_page
+        if top + self.orphans >= self.count:
+            top = self.count
+        return Page(self.object_list[bottom:top], number, self)
+
+    def _get_count(self):
+        "Returns the total number of objects, across all pages."
+        if self._count is None:
+            self._count = len(self.object_list)
+        return self._count
+    count = property(_get_count)
+
+    def _get_num_pages(self):
+        "Returns the total number of pages."
+        if self._num_pages is None:
+            hits = self.count - 1 - self.orphans
+            if hits < 1:
+                hits = 0
+            if hits == 0 and not self.allow_empty_first_page:
+                self._num_pages = 0
+            else:
+                self._num_pages = hits // self.per_page + 1
+        return self._num_pages
+    num_pages = property(_get_num_pages)
+
+    def _get_page_range(self):
+        """
+        Returns a 1-based range of pages for iterating through within
+        a template for loop.
+        """
+        return range(1, self.num_pages + 1)
+    page_range = property(_get_page_range)
+
+class QuerySetPaginator(Paginator):
+    """
+    Like Paginator, but works on QuerySets.
+    """
+    def _get_count(self):
+        if self._count is None:
+            self._count = self.object_list.count()
+        return self._count
+    count = property(_get_count)
+
+class Page(object):
+    def __init__(self, object_list, number, paginator):
+        self.object_list = object_list
+        self.number = number
+        self.paginator = paginator
+
+    def __repr__(self):
+        return '<Page %s of %s>' % (self.number, self.paginator.num_pages)
+
+    def has_next(self):
+        return self.number < self.paginator.num_pages
+
+    def has_previous(self):
+        return self.number > 1
+
+    def has_other_pages(self):
+        return self.has_previous() or self.has_next()
+
+    def next_page_number(self):
+        return self.number + 1
+
+    def previous_page_number(self):
+        return self.number - 1
+
+    def start_index(self):
+        """
+        Returns the 1-based index of the first object on this page,
+        relative to total objects in the paginator.
+        """
+        return (self.paginator.per_page * (self.number - 1)) + 1
+
+    def end_index(self):
+        """
+        Returns the 1-based index of the last object on this page,
+        relative to total objects found (hits).
+        """
+        if self.number == self.paginator.num_pages:
+            return self.paginator.count
+        return self.number * self.paginator.per_page
+
+class ObjectPaginator(Paginator):
+    """
+    Legacy ObjectPaginator class, for backwards compatibility.
+
+    Note that each method on this class that takes page_number expects a
+    zero-based page number, whereas the new API (Paginator/Page) uses one-based
+    page numbers.
     """
     def __init__(self, query_set, num_per_page, orphans=0):
+        Paginator.__init__(self, query_set, num_per_page, orphans)
+        import warnings
+        warnings.warn("The ObjectPaginator is deprecated. Use django.core.paginator.Paginator instead.", DeprecationWarning)
+
+        # Keep these attributes around for backwards compatibility.
         self.query_set = query_set
         self.num_per_page = num_per_page
-        self.orphans = orphans
         self._hits = self._pages = None
-        self._page_range = None
 
     def validate_page_number(self, page_number):
         try:
-            page_number = int(page_number)
+            page_number = int(page_number) + 1
         except ValueError:
             raise InvalidPage
-        if page_number < 0 or page_number > self.pages - 1:
+        return self.validate_number(page_number)
-            raise InvalidPage
-        return page_number
 
     def get_page(self, page_number):
-        page_number = self.validate_page_number(page_number)
+        try:
-        bottom = page_number * self.num_per_page
+            page_number = int(page_number) + 1
-        top = bottom + self.num_per_page
+        except ValueError:
-        if top + self.orphans >= self.hits:
+            raise InvalidPage
-            top = self.hits
+        return self.page(page_number).object_list
-        return self.query_set[bottom:top]
 
     def has_next_page(self, page_number):
-        "Does page $page_number have a 'next' page?"
         return page_number < self.pages - 1
 
     def has_previous_page(self, page_number):
@@ -52,7 +155,7 @@ class ObjectPaginator(object):
         relative to total objects found (hits).
         """
         page_number = self.validate_page_number(page_number)
-        return (self.num_per_page * page_number) + 1
+        return (self.num_per_page * (page_number - 1)) + 1
 
     def last_on_page(self, page_number):
         """
@@ -60,40 +163,23 @@ class ObjectPaginator(object):
         relative to total objects found (hits).
         """
         page_number = self.validate_page_number(page_number)
-        page_number += 1   # 1-base
+        if page_number == self.num_pages:
-        if page_number == self.pages:
+            return self.count
-            return self.hits
         return page_number * self.num_per_page
 
-    def _get_hits(self):
+    def _get_count(self):
-        if self._hits is None:
+        # The old API allowed for self.object_list to be either a QuerySet or a
-            # Try .count() or fall back to len().
+        # list. Here, we handle both.
+        if self._count is None:
             try:
-                self._hits = int(self.query_set.count())
+                self._count = self.object_list.count()
-            except (AttributeError, TypeError, ValueError):
+            except AttributeError:
-                # AttributeError if query_set has no object count.
+                self._count = len(self.object_list)
-                # TypeError if query_set.count() required arguments.
+        return self._count
-                # ValueError if int() fails.
+    count = property(_get_count)
-                self._hits = len(self.query_set)
-        return self._hits
 
-    def _get_pages(self):
+    # The old API called it "hits" instead of "count".
-        if self._pages is None:
+    hits = count
-            hits = (self.hits - 1 - self.orphans)
-            if hits < 1:
-                hits = 0
-            self._pages = hits // self.num_per_page + 1
-        return self._pages
-    
-    def _get_page_range(self):
-        """
-        Returns a 1-based range of pages for iterating through within 
-        a template for loop.
-        """
-        if self._page_range is None:
-            self._page_range = range(1, self.pages + 1)
-        return self._page_range
 
-    hits = property(_get_hits)
+    # The old API called it "pages" instead of "num_pages".
-    pages = property(_get_pages)
+    pages = Paginator.num_pages
-    page_range = property(_get_page_range)

tests/modeltests/pagination/models.py

@@ -4,6 +4,11 @@
 Django provides a framework for paginating a list of objects in a few lines
 of code. This is often useful for dividing search results or long lists of
 objects into easily readable pages.
+
+In Django 0.96 and earlier, a single ObjectPaginator class implemented this
+functionality. In the Django development version, the behavior is split across
+two classes -- Paginator and Page -- that are more easier to use. The legacy
+ObjectPaginator class is deprecated.
 """
 
 from django.db import models
@@ -16,70 +21,206 @@ class Article(models.Model):
         return self.headline
 
 __test__ = {'API_TESTS':"""
-# prepare a list of objects for pagination
+# Prepare a list of objects for pagination.
 >>> from datetime import datetime
 >>> for x in range(1, 10):
 ...     a = Article(headline='Article %s' % x, pub_date=datetime(2005, 7, 29))
 ...     a.save()
 
-# create a basic paginator, 5 articles per page
+####################################
+# New/current API (Paginator/Page) #
+####################################
+
+>>> from django.core.paginator import Paginator, InvalidPage
+>>> paginator = Paginator(Article.objects.all(), 5)
+>>> paginator.count
+9
+>>> paginator.num_pages
+2
+>>> paginator.page_range
+[1, 2]
+
+# Get the first page.
+>>> p = paginator.page(1)
+>>> p
+<Page 1 of 2>
+>>> p.object_list
+[<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>, <Article: Article 5>]
+>>> p.has_next()
+True
+>>> p.has_previous()
+False
+>>> p.has_other_pages()
+True
+>>> p.next_page_number()
+2
+>>> p.previous_page_number()
+0
+>>> p.start_index()
+1
+>>> p.end_index()
+5
+
+# Get the second page.
+>>> p = paginator.page(2)
+>>> p
+<Page 2 of 2>
+>>> p.object_list
+[<Article: Article 6>, <Article: Article 7>, <Article: Article 8>, <Article: Article 9>]
+>>> p.has_next()
+False
+>>> p.has_previous()
+True
+>>> p.has_other_pages()
+True
+>>> p.next_page_number()
+3
+>>> p.previous_page_number()
+1
+>>> p.start_index()
+6
+>>> p.end_index()
+9
+
+# Invalid pages raise InvalidPage.
+>>> paginator.page(0)
+Traceback (most recent call last):
+...
+InvalidPage: ...
+>>> paginator.page(3)
+Traceback (most recent call last):
+...
+InvalidPage: ...
+
+# Empty paginators with allow_empty_first_page=True.
+>>> paginator = Paginator(Article.objects.filter(id=0), 5, allow_empty_first_page=True)
+>>> paginator.count
+0
+>>> paginator.num_pages
+1
+>>> paginator.page_range
+[1]
+
+# Empty paginators with allow_empty_first_page=False.
+>>> paginator = Paginator(Article.objects.filter(id=0), 5, allow_empty_first_page=False)
+>>> paginator.count
+0
+>>> paginator.num_pages
+0
+>>> paginator.page_range
+[]
+
+# Paginators work with regular lists/tuples, too -- not just with QuerySets.
+>>> paginator = Paginator([1, 2, 3, 4, 5, 6, 7, 8, 9], 5)
+>>> paginator.count
+9
+>>> paginator.num_pages
+2
+>>> paginator.page_range
+[1, 2]
+
+# Get the first page.
+>>> p = paginator.page(1)
+>>> p
+<Page 1 of 2>
+>>> p.object_list
+[1, 2, 3, 4, 5]
+>>> p.has_next()
+True
+>>> p.has_previous()
+False
+>>> p.has_other_pages()
+True
+>>> p.next_page_number()
+2
+>>> p.previous_page_number()
+0
+>>> p.start_index()
+1
+>>> p.end_index()
+5
+
+################################
+# Legacy API (ObjectPaginator) #
+################################
+
 >>> from django.core.paginator import ObjectPaginator, InvalidPage
 >>> paginator = ObjectPaginator(Article.objects.all(), 5)
-
-# the paginator knows how many hits and pages it contains
 >>> paginator.hits
 9
-
 >>> paginator.pages
 2
+>>> paginator.page_range
+[1, 2]
 
-# get the first page (zero-based)
+# Get the first page.
 >>> paginator.get_page(0)
 [<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>, <Article: Article 5>]
-
-# get the second page
->>> paginator.get_page(1)
-[<Article: Article 6>, <Article: Article 7>, <Article: Article 8>, <Article: Article 9>]
-
-# does the first page have a next or previous page?
 >>> paginator.has_next_page(0)
 True
-
 >>> paginator.has_previous_page(0)
 False
-
-# check the second page
->>> paginator.has_next_page(1)
-False
-
->>> paginator.has_previous_page(1)
-True
-
 >>> paginator.first_on_page(0)
 1
->>> paginator.first_on_page(1)
-6
 >>> paginator.last_on_page(0)
 5
+
+# Get the second page.
+>>> paginator.get_page(1)
+[<Article: Article 6>, <Article: Article 7>, <Article: Article 8>, <Article: Article 9>]
+>>> paginator.has_next_page(1)
+False
+>>> paginator.has_previous_page(1)
+True
+>>> paginator.first_on_page(1)
+6
 >>> paginator.last_on_page(1)
 9
 
+# Invalid pages raise InvalidPage.
+>>> paginator.get_page(-1)
+Traceback (most recent call last):
+...
+InvalidPage: ...
+>>> paginator.get_page(2)
+Traceback (most recent call last):
+...
+InvalidPage: ...
+
+# Empty paginators with allow_empty_first_page=True.
+>>> paginator = ObjectPaginator(Article.objects.filter(id=0), 5)
+>>> paginator.count
+0
+>>> paginator.num_pages
+1
+>>> paginator.page_range
+[1]
+
+##################
+# Orphan support #
+##################
+
 # Add a few more records to test out the orphans feature.
 >>> for x in range(10, 13):
 ...     Article(headline="Article %s" % x, pub_date=datetime(2006, 10, 6)).save()
 
-# With orphans set to 3 and 10 items per page, we should get all 12 items on a single page:
+# With orphans set to 3 and 10 items per page, we should get all 12 items on a single page.
+>>> paginator = Paginator(Article.objects.all(), 10, orphans=3)
+>>> paginator.num_pages
+1
+
+# With orphans only set to 1, we should get two pages.
+>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=1)
+>>> paginator.num_pages
+2
+
+# LEGACY: With orphans set to 3 and 10 items per page, we should get all 12 items on a single page.
 >>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=3)
 >>> paginator.pages
 1
 
-# With orphans only set to 1, we should get two pages:
+# LEGACY: With orphans only set to 1, we should get two pages.
 >>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=1)
 >>> paginator.pages
 2
-
-# The paginator can provide a list of all available pages.
->>> paginator = ObjectPaginator(Article.objects.all(), 10)
->>> paginator.page_range
-[1, 2]
 """}