Fix Issue 1076: Implemented Select2 Initial Values

src/dal_select2/widgets.py

@@ -1,4 +1,5 @@
 """Select2 widget implementation module."""
+import ast
 
 try:
     from functools import lru_cache
@@ -113,15 +114,55 @@ def media(self):
     autocomplete_function = 'select2'
 
 
+class Select2InitialRenderMixin:
+    def render(self, name, value, attrs=None, renderer=None):
+        if not value:
+            return super().render(name, value, attrs=attrs, renderer=renderer)
+
+        values = []
+
+        if isinstance(value, str):
+            try:
+                parsed = ast.literal_eval(value)
+                if isinstance(parsed, (list, tuple)):
+                    values = [v.strip() for v in parsed if v]
+                else:
+                    values = [str(parsed)]
+            except (ValueError, SyntaxError):
+                values = [v.strip() for v in value.split(',') if v.strip()]
+
+        elif isinstance(value, (list, tuple)):
+            values = list(value)
+
+        else:
+            values = [value]
+
+        existing = dict(self.choices)
+        extended = [(v, v) for v in values if v not in existing]
+        if extended:
+            original_choices = self.choices
+            self.choices = list(self.choices) + extended
+            try:
+                return super().render(name, values, attrs=attrs, renderer=renderer)
+            finally:
+                self.choices = original_choices
+
+        return super().render(name, values, attrs=attrs, renderer=renderer)
+
+
 class Select2(Select2WidgetMixin, Select):
     """Select2 widget for regular choices."""
 
 
-class Select2Multiple(Select2WidgetMixin, SelectMultiple):
+class Select2Multiple(Select2InitialRenderMixin, Select2WidgetMixin, SelectMultiple):
     """Select2Multiple widget for regular choices."""
 
 
-class ListSelect2(WidgetMixin, Select2WidgetMixin, forms.Select):
+class ListSelect2(
+    Select2InitialRenderMixin,
+    WidgetMixin, Select2WidgetMixin,
+    forms.Select
+):
     """Select widget for regular choices and Select2."""
 
 

test_project/tests/test_widgets.py

@@ -9,7 +9,10 @@
 from django import forms
 from django import http
 from django import test
+from django.http import HttpResponse
 from django.urls import re_path as url
+from django.views import View
+
 try:
     from django.urls import reverse
 except ImportError:
@@ -19,10 +22,15 @@
 import mock
 
 
+class DummyView(View):
+    def get(self, request):
+        return HttpResponse("ok")
+
+
 urlpatterns = [
     url(
         r'^test-url/$',
-        mock.Mock(),
+        DummyView.as_view(),  # replace with sample Mock View
         name='test_url'
     ),
 ]
@@ -158,3 +166,45 @@ def render_forward_conf(self, id):
         # attrs with id
         observed = widget.render('myname', '', attrs={'id': 'myid'})
         self.assertEqual(observed, 'myid')
+
+
+@override_settings(ROOT_URLCONF='tests.test_widgets')
+class Select2InitialRenderMixinTest(test.TestCase):
+    def test_listselect2_adds_missing_selected_value(self):
+        class Form(forms.Form):
+            test = forms.ChoiceField(
+                widget=select2_widget.ListSelect2(url=reverse('test_url')),
+                required=False,
+            )
+
+        form = Form(initial={'test': 'Urdu'})
+        rendered = form.as_p()
+
+        assert 'value="Urdu" selected' in rendered
+
+    def test_select2multiple_adds_multiple_selected_values(self):
+        class Form(forms.Form):
+            test = forms.MultipleChoiceField(
+                widget=select2_widget.Select2Multiple(url=reverse('test_url')),
+                required=False,
+            )
+
+        form = Form(initial={'test': ['English', 'Urdu']})
+        rendered = form.as_p()
+
+        assert 'value="English" selected' in rendered
+        assert 'value="Urdu" selected' in rendered
+
+    def test_select2multiple_handles_stringified_list(self):
+        class Form(forms.Form):
+            test = forms.MultipleChoiceField(
+                widget=select2_widget.Select2Multiple(url=reverse('test_url')),
+                required=False,
+            )
+
+        form = Form()
+        form.fields['test'].initial = "['English', 'Urdu']"
+        rendered = form.as_p()
+
+        assert 'value="English" selected' in rendered
+        assert 'value="Urdu" selected' in rendered