Start offering page with visible form

src/servala/frontend/forms/service.py

@@ -25,7 +25,9 @@ class ServiceFilterForm(forms.Form):
 
 class ControlPlaneSelectForm(forms.Form):
     control_plane = forms.ModelChoiceField(
-        queryset=ControlPlane.objects.none(), label=_("Service Provider Zone")
+        queryset=ControlPlane.objects.none(),
+        label=_("Service Provider Zone"),
+        empty_label=None,
     )
 
     def __init__(self, *args, planes=None, **kwargs):

src/servala/frontend/views/service.py

@@ -68,26 +68,42 @@ class ServiceOfferingDetailView(OrganizationViewMixin, HtmxViewMixin, DetailView
         data = None
         if "control_plane" in self.request.GET:
             data = self.request.GET
+        elif self.request.method == "POST" and self.context_object:
+            data = {"control_plane": self.context_object.control_plane_id}
         return ControlPlaneSelectForm(data=data, planes=self.planes)
 
+    @cached_property
+    def selected_plane(self):
+        if self.select_form.data and self.select_form.is_valid():
+            return self.select_form.cleaned_data["control_plane"]
+        field = self.select_form.fields["control_plane"]
+        return field.initial or field.queryset.first()
+
+    @cached_property
+    def context_object(self):
+        if self.request.method == "POST":
+            return ServiceOfferingControlPlane.objects.filter(
+                pk=self.request.POST.get("context"),
+                # Make sure we don’t use a malicious ID
+                control_plane__in=self.planes,
+            ).first()
+        return ServiceOfferingControlPlane.objects.filter(
+            control_plane=self.selected_plane, service_offering=self.object
+        ).first()
+
+    def get_instance_form(self):
+        return self.context_object.model_form_class(
+            data=self.request.POST if self.request.method == "POST" else None,
+            initial={
+                "organization": self.request.organization,
+                "context": self.context_object,
+            },
+        )
+
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
         context["select_form"] = self.select_form
         context["has_control_planes"] = self.planes.exists()
-        if "control_plane" in self.request.GET:
-            if self.select_form.is_valid():
-                context["selected_plane"] = self.select_form.cleaned_data[
-                    "control_plane"
-                ]
-                try:
-                    so_cp = ServiceOfferingControlPlane.objects.filter(
-                        control_plane=self.select_form.cleaned_data["control_plane"],
-                        service_offering=self.object,
-                    ).first()
-                    if not so_cp:
-                        context["form_error"] = True
-                except Exception:
-                    context["form_error"] = True
-                else:
-                    context["service_form"] = so_cp.model_form_class()
+        context["selected_plane"] = self.selected_plane
+        context["service_form"] = self.get_instance_form()
         return context