Implement primary answer management with HTMX support, including form for selecting or creating answers and display templates

anatomy/views.py

@@ -46,6 +46,7 @@ from .forms import (
     AnatomyQuestionForm,
     ExamForm,
     SuggestIncorrectAnswerForm,
+    PrimaryAnswerForm,
 )
 from .models import (
     AnatomyQuestion,
@@ -1655,4 +1656,58 @@ def question_add_exam(request, question_id: int):
             return HttpResponse(mark_safe(html))
 
 
-    raise PermissionDenied()
+    raise PermissionDenied()
+
+
+@login_required
+def primary_answer_htmx(request, pk: int):
+    """HTMX endpoint to render or update a question's primary answer.
+
+    GET: render the form for selecting/creating primary answer.
+    POST: create/select answer and set `question.primary_answer`, then
+    return the display fragment.
+    """
+    if not request.htmx:
+        raise PermissionDenied()
+
+    question = get_object_or_404(AnatomyQuestion, pk=pk)
+
+    if not question.can_edit(request.user):
+        return HttpResponse("Invalid permissions", status=403)
+
+    if request.method == "POST":
+        form = PrimaryAnswerForm(request.POST, question=question)
+        if form.is_valid():
+            new_text = form.cleaned_data.get("new_answer", "").strip()
+            existing = form.cleaned_data.get("existing_answer", "")
+
+            if new_text:
+                # create a new Answer and mark it CORRECT
+                ans = Answer(question=question, answer=new_text, proposed=False, status=Answer.MarkOptions.CORRECT)
+                ans.save()
+                question.primary_answer = ans
+                question.save(update_fields=["primary_answer"])
+            elif existing:
+                try:
+                    aid = int(existing)
+                    ans = Answer.objects.get(pk=aid, question=question)
+                    question.primary_answer = ans
+                    question.save(update_fields=["primary_answer"])
+                except (ValueError, Answer.DoesNotExist):
+                    return HttpResponse("Invalid answer choice", status=400)
+
+            # return display fragment
+            return render(request, "anatomy/partials/primary_answer_display.html", {"question": question})
+        else:
+            return HttpResponse("Invalid form", status=400)
+
+    # Handle cancel request to restore original state
+    if request.method == "GET" and request.GET.get("cancel"):
+        if question.primary_answer:
+            return render(request, "anatomy/partials/primary_answer_display.html", {"question": question})
+        else:
+            return render(request, "anatomy/partials/primary_answer_empty.html", {"question": question})
+
+    # GET - render form
+    form = PrimaryAnswerForm(question=question)
+    return render(request, "anatomy/partials/primary_answer_form.html", {"form": form, "question": question})