Add ModelSelect2Mixin.result_from_instance method (#272)

Enable users to easily override the result JSON per widget without implementing a separate view.

---------

Co-authored-by: Johannes Maron <johannes@maron.family>

django_select2/forms.py

@@ -554,6 +554,28 @@ def label_from_instance(obj):
         """
         return str(obj)
 
+    def result_from_instance(self, obj, request):
+        """
+        Return a dictionary representing the object.
+
+        Can be overridden to change the result returned by
+        :class:`.AutoResponseView` for each object.
+
+        The request passed in will correspond to the request sent to the
+        :class:`.AutoResponseView` by the widget.
+
+        Example usage::
+
+            class MyWidget(ModelSelect2Widget):
+                def result_from_instance(obj, request):
+                    return {
+                        'id': obj.pk,
+                        'text': self.label_from_instance(obj),
+                        'extra_data': obj.extra_data,
+                    }
+        """
+        return {"id": obj.pk, "text": self.label_from_instance(obj)}
+
 
 class ModelSelect2Widget(ModelSelect2Mixin, HeavySelect2Widget):
     """

django_select2/views.py

@@ -21,6 +21,9 @@ def get(self, request, *args, **kwargs):
         """
         Return a :class:`.django.http.JsonResponse`.
 
+        Each result will be rendered by the widget's
+        :func:`django_select2.forms.ModelSelect2Mixin.result_from_instance` method.
+
         Example::
 
             {
@@ -41,7 +44,7 @@ def get(self, request, *args, **kwargs):
         return JsonResponse(
             {
                 "results": [
-                    {"text": self.widget.label_from_instance(obj), "id": obj.pk}
+                    self.widget.result_from_instance(obj, request)
                     for obj in context["object_list"]
                 ],
                 "more": context["page_obj"].has_next(),

tests/test_forms.py

@@ -438,6 +438,15 @@ def test_get_queryset(self):
         widget.queryset = Genre.objects.all()
         assert isinstance(widget.get_queryset(), QuerySet)
 
+    def test_result_from_instance_ModelSelect2Widget(self, genres):
+        widget = ModelSelect2Widget()
+        widget.model = Genre
+        genre = Genre.objects.first()
+        assert widget.result_from_instance(genre, request=None) == {
+            "id": genre.pk,
+            "text": str(genre),
+        }
+
     def test_tag_attrs_Select2Widget(self):
         widget = Select2Widget()
         output = widget.render("name", "value")

tests/test_views.py

@@ -4,7 +4,11 @@
 
 from django_select2.cache import cache
 from django_select2.forms import ModelSelect2Widget
-from tests.testapp.forms import AlbumModelSelect2WidgetForm, ArtistCustomTitleWidget
+from tests.testapp.forms import (
+    AlbumModelSelect2WidgetForm,
+    ArtistCustomTitleWidget,
+    CityForm,
+)
 from tests.testapp.models import Genre
 
 try:
@@ -84,6 +88,23 @@ def test_label_from_instance(self, artists, client):
             "results"
         ]
 
+    def test_result_from_instance(self, cities, client):
+        url = reverse("django_select2:auto-json")
+
+        form = CityForm()
+        assert form.as_p()
+        field_id = form.fields["city"].widget.field_id
+        city = cities[0]
+        response = client.get(url, {"field_id": field_id, "term": city.name})
+        assert response.status_code == 200
+        data = json.loads(response.content.decode("utf-8"))
+        assert data["results"]
+        assert {
+            "id": city.pk,
+            "text": smart_str(city),
+            "country": smart_str(city.country),
+        } in data["results"]
+
     def test_url_check(self, client, artists):
         artist = artists[0]
         form = AlbumModelSelect2WidgetForm()

tests/testapp/forms.py

@@ -232,3 +232,17 @@ class Meta:
         model = models.Groupie
         fields = "__all__"
         widgets = {"obsession": ArtistCustomTitleWidget}
+
+
+class CityModelSelect2Widget(ModelSelect2Widget):
+    model = City
+    search_fields = ["name"]
+
+    def result_from_instance(self, obj, request):
+        return {"id": obj.pk, "text": obj.name, "country": str(obj.country)}
+
+
+class CityForm(forms.Form):
+    city = forms.ModelChoiceField(
+        queryset=City.objects.all(), widget=CityModelSelect2Widget(), required=False
+    )