Django DetailView update on one page not working - NoReverseMatch error - django

Question

I have a problem with update of my DetailView, so once i try to submit the updated values I am receiving an error NoReverseMatch at /task/164/. Could you please give me a hint what is wrong?
Thx!
urls:
path('excel_upload', ex_views.ExcelUploadView.as_view(), name='excel-upload'),
path('user_list', ex_views.UsersListView.as_view(), name = "user-list"),
path('excel_table', ex_views.ExcelTableView.as_view(), name = "excel-table"),
path("task/add", ex_views.TaskAddView.as_view(), name="task-add"),
path("task/<int:pk>/", ex_views.TaskDetailView.as_view(), name="task-detail"),
forms.py
class AddEditTaskForm(forms.ModelForm):
class Meta:
model = Task
exclude = ['created_by']
widgets = {
"due_date": forms.DateInput(attrs={'type':'date'}),
"completed_date": forms.DateInput(attrs={'type': 'date'}),
"name":forms.TextInput(),
"note": forms.Textarea(),
}
views.py
class TaskDetailView(DetailView):
model = Task
template_name = "hana/task_detail.html"
# Add POST method
def post(self, request, pk):
task = get_object_or_404(Task, pk=pk)
form = AddEditTaskForm(request.POST, instance=task)
if "add_edit_task" in request.POST:
if form.is_valid():
form.save()
messages.success(request, "The task has been edited.")
return redirect('excel-table')
return render(request, 'hana/task_detail.html', {'form': form})
error:
NoReverseMatch at /task/164/
Reverse for 'task-detail' with arguments '('',)' not found. 1 pattern(s) tried: ['task\/(?P[0-9]+)\/$']
Request Method: POST
Request URL: http://127.0.0.1:8000/task/164/
Django Version: 3.0.6
Exception Type: NoReverseMatch
Exception Value:
Reverse for 'task-detail' with arguments '('',)' not found. 1 pattern(s) tried: ['task\/(?P[0-9]+)\/$']
Exception Location: /home/lukasz/envtest2/lib/python3.6/site-packages/django/urls/resolvers.py in _reverse_with_prefix, line 677
template:
<form method="post" action="{% url 'task-detail' object.id %}" role="form" class="d-inline">
{% csrf_token %}
<div style="display:inline;">
<button class="btn btn-info btn-sm" type="submit" name="toggle_done">
{% if task.completed %} Mark Not Done {% else %} Mark Done {% endif %}
</button>
</div>
</form>
<a class="btn btn-danger btn-sm mt-1 mb-1" href={% url 'task-delete' object.id %}">Delete</a>

Answer 1

Your issue is caused by mixing class based and function based views. Your function based post view uses the same template as your class based TaskDetailView, but since it doesn't have the same "magic" inherited from DetailView, there is no object passed in the context dictionary (you only pass form).
The proper fix would be to stick to the same view architecture when possible, but a trivial fix would be:
return render(request, 'hana/task_detail.html', {'form': form, 'object': task})