Add ajax related field filters

jet/filters.py

@@ -0,0 +1,36 @@
+from django.contrib.admin import RelatedFieldListFilter
+from django.contrib.admin.utils import get_model_from_relation
+from django.core.urlresolvers import reverse
+from django.forms.utils import flatatt
+from django.utils.encoding import smart_text
+from django.utils.html import format_html
+
+
+class RelatedFieldAjaxListFilter(RelatedFieldListFilter):
+    ajax_attrs = None
+
+    def has_output(self):
+        return True
+
+    def field_choices(self, field, request, model_admin):
+        app_label = field.related_model._meta.app_label
+        model_name = field.related_model._meta.object_name
+
+        self.ajax_attrs = format_html('{}', flatatt({
+            'data-app-label': app_label,
+            'data-model': model_name,
+            'data-ajax--url': reverse('jet:model_lookup'),
+            'data-queryset--lookup': self.lookup_kwarg
+        }))
+
+        if self.lookup_val is None:
+            return []
+
+        other_model = get_model_from_relation(field)
+        if hasattr(field, 'rel'):
+            rel_name = field.rel.get_related_field().name
+        else:
+            rel_name = other_model._meta.pk.name
+
+        queryset = field.related_model._default_manager.filter(**{rel_name: self.lookup_val}).all()
+        return [(x._get_pk_val(), smart_text(x)) for x in queryset]

jet/templates/admin/filter.html

@@ -1,6 +1,6 @@
 {% load i18n %}
 
-<select class="changelist-filter-select">
+<select class="changelist-filter-select{% if spec.ajax_attrs %} ajax{% endif %}"{% if spec.ajax_attrs %}{{ spec.ajax_attrs }}{% endif %}>
     {% for choice in choices %}
         {% if forloop.first %}
             <option data-url="{{ choice.query_string|iriencode }}">{% blocktrans with filter_title=title %}{{ filter_title }}{% endblocktrans %}</option>