I have a Project model

class Project(models.Model)
    name = models.CharField(max_length=255)
    members = models.ManyToManyField(User, related_name="members")

and I am using a classbased Update view to restrict only those users who are members of the project.

class ProjectUpdateView(LoginRequiredMixin, UserPassesTestMixin, UpdateView):
    model = Project
    fields = ["name"]

    def test_func(self):
        members = self.get_object().members.all()
        if members.contains(self.request.user):
            return True
        return False

After looking at the SQL queries through Djang Debug Toolbar, I see the query is duplicated 2 times. the 1st instance is from this test_func and the other instance is from django generic views, how can I resolve the duplicated query issue

CodePudding user response：

Just filter the queryset to retrieve only projects where the request.user is a member of that Project, so:

class ProjectUpdateView(LoginRequiredMixin, UpdateView):
    model = Project
    fields = ['name']

    def get_querset(self):
        return Project.objects.filter(members=self.request.user)

Note: It is normally better to make use of the settings.AUTH_USER_MODEL ^[Django-doc] to refer to the user model, than to use the User model ^[Django-doc] directly. For more information you can see the referencing the User model section of the documentation.

Note: The related_name=… parameter ^[Django-doc] is the name of the relation in reverse, so from the User model to the Project model in this case. Therefore it (often) makes not much sense to name it the same as the forward relation. You thus might want to consider renaming the members relation to projects.