Then I inject this mixin in my generic views like this:

python
class ProposalCreate(LoginRequiredMixin, HTMXCreateView):
    model = FakeProposal
    form_class = ProposalForm
    form_template_name = "proposals/proposal_create_fragment.html"
    hx_target_form_invalid = "#fragment_create_proposal"


class ProposalUpdate(LoginRequiredMixin, HTMXUpdateView):
    model = FakeProposal
    form_class = ProposalForm
    form_template_name = "proposals/proposal_update_fragment.html"
    hx_target_form_invalid = "#fragment_update_proposal"