Cast data to QueryDict in LinkWidget.render

django_filters/widgets.py

@@ -6,9 +6,9 @@
 from django import forms
 from django.db.models.fields import BLANK_CHOICE_DASH
 from django.forms.utils import flatatt
+from django.http import QueryDict
 from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import force_str
-from django.utils.http import urlencode
 from django.utils.safestring import mark_safe
 from django.utils.translation import gettext as _
 
@@ -56,13 +56,13 @@ def render_option(self, name, selected_choices, option_value, option_label):
         option_value = force_str(option_value)
         if option_label == BLANK_CHOICE_DASH[0][1]:
             option_label = _("All")
-        data = self.data.copy()
+
+        data = QueryDict(mutable=True)
+        data.update(self.data)
         data[name] = option_value
+
         selected = data == self.data or option_value in selected_choices
-        try:
-            url = data.urlencode()
-        except AttributeError:
-            url = urlencode(data)
+        url = data.urlencode()
         return self.option_string() % {
             "attrs": selected and ' class="selected"' or "",
             "query_string": url,

tests/test_widgets.py

@@ -1,6 +1,6 @@
 from django.forms import NumberInput, Select, TextInput
 from django.test import TestCase
-
+from django.utils.datastructures import MultiValueDict
 from django_filters.widgets import (
     BaseCSVWidget,
     BooleanWidget,
@@ -143,6 +143,25 @@ def test_widget_with_blank_choice(self):
             </ul>""",
         )
 
+    def test_widget_multivaluedict(self):
+        choices = (
+            ("", "---------"),
+            ("test-val1", "test-label1"),
+            ("test-val2", "test-label2"),
+        )
+
+        w = LinkWidget(choices=choices)
+        w.value_from_datadict(MultiValueDict(), {}, "price")
+        self.assertHTMLEqual(
+            w.render("price", ""),
+            """
+            <ul>
+                <li><a class="selected" href="?price=">All</a></li>
+                <li><a href="?price=test-val1">test-label1</a></li>
+                <li><a href="?price=test-val2">test-label2</a></li>
+            </ul>""",
+        )
+
     def test_widget_value_from_datadict(self):
         w = LinkWidget()
         data = {"price": "test-val1"}