first cut at pagination

In the template, I had actually hoped to use the {%
bootstrap_pagination %} template tags provided by the
django-bootstrap3 app that we're using, but the documentation was
uninformative on how to use it, and glancing at the source, it kind of
seems like it assumes that pages are given in the query string (am I
misunderstanding something?!), so I guess we'll just have to do it
ourselves. What we have in this commit isn't quite right (for example,
there's a link to page zero, which 500s on an EmptyPage "That page
number is less than 1" exception), but it's an okayish start. We'll
also want to abstract this into a function (as with `scored_context`).

[#21]

core/views.py

@@ -12,7 +12,9 @@
 from django.contrib.auth.models import User
 from django.contrib import messages
 from django.core.urlresolvers import reverse
+from django.core.paginator import Paginator
 from django.db import IntegrityError
+from django.conf import settings
 
 from core.models import FinetoothUser, Post, Comment, Tag
 from core.colorize import stylesheet
@@ -32,11 +34,20 @@ def scored_context(scoreables, context):
     })
     return context
 
-def home(request):
-    posts = Post.objects.all()
+def home(request, page):
+    page = int(page) if page else 1
+    all_posts = Post.objects.all()
+    requested = request.GET.get('results')
+    posts_per_page = (int(requested) if (requested and requested.isdigit())
+                      else settings.POSTS_PER_PAGE)
+    paginator = Paginator(all_posts, posts_per_page)
+    if page > paginator.num_pages:
+        # pagination is 1-indexed
+        return redirect("home", paginator.num_pages)
+    posts = paginator.page(page)
     return render(
         request, "home.html",
-        scored_context(posts, {'posts': posts})
+        scored_context(posts, {'posts': posts, 'page': page})
     )
 
 def serve_stylesheet(request, low_score, low_color, high_score, high_color):

settings.py

@@ -104,3 +104,5 @@
         },
     }
 }
+
+POSTS_PER_PAGE = 15

templates/home.html

@@ -14,4 +14,9 @@
   </a></p>
 </div>
 {% endfor %}
+
+<ul class="pager">
+  <li><a href="/page/{{ page|add:"-1" }}">Previous</a></li>
+  <li><a href="/page/{{ page|add:"1" }}">Next</a></li>
+</ul>
 {% endblock %}

urls.py

@@ -4,7 +4,7 @@
 
 urlpatterns = patterns(
     '',
-    url(r'^$', 'core.views.home', name='home'),
+    url(r'^(?:page/(\d+)/)?$', 'core.views.home', name='home'),
     url(r'^valuation_(-?\d+)-([0-9a-f]{6})_(-?\d+)-([0-9a-f]{6}).css$',
         'core.views.serve_stylesheet', name='stylesheet'),
     url(r'^(\d+)/$', 'core.views.show_post', name="show_post"),