feat: add optgroups form field

app/apps/common/fields/forms/grouped_select.py

@@ -0,0 +1,49 @@
+from django import forms
+from django.forms.models import ModelChoiceIterator
+from django.utils.translation import gettext_lazy as _
+
+
+class GroupedModelChoiceIterator(ModelChoiceIterator):
+    def __init__(self, field, group_by):
+        self.group_by = group_by
+        super().__init__(field)
+
+    def __iter__(self):
+        if self.field.empty_label is not None:
+            yield "", self.field.empty_label
+
+        queryset = self.queryset
+        grouped_queryset = {}
+
+        for obj in queryset:
+            group_key = getattr(obj, self.group_by, None) if self.group_by else None
+            grouped_queryset.setdefault(group_key, []).append(obj)
+
+        for group, items in grouped_queryset.items():
+            yield (
+                group if group is not None else _("Ungrouped"),
+                [
+                    (self.field.prepare_value(obj), self.field.label_from_instance(obj))
+                    for obj in items
+                ],
+            )
+
+
+class GroupedModelChoiceField(forms.ModelChoiceField):
+    def __init__(self, *args, group_by=None, **kwargs):
+        self.group_by = group_by
+        super().__init__(*args, **kwargs)
+
+    @property
+    def choices(self):
+        return GroupedModelChoiceIterator(self, self.group_by)
+
+
+class GroupedModelMultipleChoiceField(forms.ModelMultipleChoiceField):
+    def __init__(self, *args, group_by=None, **kwargs):
+        self.group_by = group_by
+        super().__init__(*args, **kwargs)
+
+    @property
+    def choices(self):
+        return GroupedModelChoiceIterator(self, self.group_by)