read_only_admin.py

from django.contrib import admin


class ReadOnlyAdminMixin:
    def get_readonly_fields(self, request, obj=None):
        fields = list(self.fields or []) + \
            [f.name for f in self.model._meta.fields]
        _id = self.model._meta.pk.name
        fields = [_id] + list({f: f for f in fields if f != _id}.keys())
        return fields

    def has_add_permission(self, request):
        return False

    def has_delete_permission(self, request, obj=None):
        return False


class ReadOnlyInlineMixin(ReadOnlyAdminMixin):
    extra = 0
    show_change_link = True
    max_num = 0
    can_delete = False


def read_only_inline(model):
    class ReadOnlyInline(ReadOnlyInlineMixin, admin.TabularInline):
        pass
    ReadOnlyInline.model = model
    return ReadOnlyInline