Fix page URI: do not lose search query when changing page

membership/templates/membership/paginating_snippet.html

@@ -1,21 +1,23 @@
 {% load i18n %}
+{% load page %}
+
 {% if is_paginated %}
 <div class="pagination">
   <span class="step-links">
     {% if page_obj.has_previous %}
-    <a href="?page={{ page_obj.previous_page_number }}{% if search_query %}&query={{ search_query }}{% endif %}{% if sort %}&sort={{ sort }}{% endif %}">{% trans "Previous" %}</a>
+    <a href="{% page "previous" %}">{% trans "Previous" %}</a>
     {% endif %}
 
     {% for pagenum in paginator.page_range %}
     {% ifnotequal pagenum page %}
-      <a href="?page={{ pagenum }}{% if search_query %}&query={{ search_query }}{% endif %}{% if sort %}&sort={{ sort }}{% endif %}">{{ pagenum }}</a>
+      <a href="{% page pagenum %}">{{ pagenum }}</a>
     {% else %}
       <strong>{{ pagenum }}</strong>
     {% endifnotequal %}
     {% endfor %}
 
     {% if page_obj.has_next %}
-    <a href="?page={{ page_obj.next_page_number }}{% if search_query %}&query={{ search_query }}{% endif %}{% if sort %}&sort={{ sort }}{% endif %}">{% trans "Next" %}</a>
+    <a href="{% page "next" %}">{% trans "Next" %}</a>
     {% endif %}
   </span>
 </div>

membership/templatetags/page.py

@@ -0,0 +1,42 @@
+from __future__ import unicode_literals
+
+from django import template
+from django.http import QueryDict
+
+register = template.Library()
+
+
+class Page(template.Node):
+    def __init__(self, field):
+        self.page = field.replace('"', '')
+
+    def render(self, context):
+        """Return querystring part of URI
+        >>> p = Page("5")
+        >>> p.render({'querystring': {}})
+        u'?page=5'
+        >>> p.render({'querystring': {'sort':'id:1'}})
+        u'?sort=id:1&page=5'
+        """
+        querystring = context.get('querystring', {})
+        if isinstance(querystring, QueryDict):
+            querystring = querystring.dict()
+        page_obj = context.get('page_obj')
+        if page_obj is None:
+            querystring['page'] = unicode(self.page)
+        elif self.page == 'previous':
+            querystring['page'] = str(page_obj.previous_page_number())
+        elif self.page == 'next':
+            querystring['page'] = str(page_obj.next_page_number())
+        else:
+            querystring['page'] = str(context.get(self.page))
+        return "?" + "&".join(["=".join(k) for k in querystring.items()])
+
+
+def do_page(parser, token):
+    """Get sorturl by sort field"""
+    tag_name, field = token.split_contents()
+    return Page(field)
+
+
+register.tag('page', do_page)