django if else 模板标签使用对象 from with template 标签

问：

我有一个 if/else 语句，用于确定哪个按钮将显示在我的 base.py 模板中。通过我的研究，我认为我走在正确的道路上，但无论 enddate 字段是 null 还是填充，都会显示 endcast 按钮。

型：

class Cast(models.Model):
    id = models.AutoField(db_column='Id')
    startdate = models.DateTimeField(db_column='StartDate')
    enddate = models.DateTimeField(db_column='EndDate')

    class Meta:
        managed = True
        db_table = 'Cast'
        verbose_name_plural = "Cast"
        get_latest_by = "pk"

模板块：

    <div class="top-button-container stickey-top">
        {% with last=Cast.objects.latest %}
            {% if last.enddate %}
                <button type="button" class="btn btn-danger btn-lg btn-block">
                    <a class="nav-link" href="{% url 'caststart' %}">Start Cast</a>
                </button>
            {% else %}
                <button type="button" class="btn btn-danger btn-lg btn-block">
                    <a class="nav-link" href="{% url 'cast_end' %}">End Cast</a>
                </button>
            {% endif %}
        {% endwith %}
    </div>

视图：

def caststart(request):
    context ={}
    form = StartCastForm(request.POST or None)
    if request.method == "POST":
        form = StartCastForm(request.POST, request.FILES)
        if form.is_valid():
            form.save()
            castid=Cast.objects.last()
            return HttpResponseRedirect("%i/castend" % castid.pk)
    else:
        form = StartCastForm 
        if 'submitted' in request.GET:
            submitted = True
            return render(request, 'wwdb/casts/caststart.html', {'form':form, 'submitted':submitted, 'id':id})

    context['form']= form

    return render(request, "wwdb/casts/caststart.html", context)

def cast_end(request):
    last = Cast.objects.latest('pk')
    return redirect('castend', id=last.pk)

def castend(request, id):
    context ={}
    obj = get_object_or_404(Cast, id = id)
    form = EndCastForm(request.POST or None, instance = obj)
    if request.method == 'POST':
        cast=Cast.objects.last()
        if form.is_valid():
            form.save()
            cast.refresh_from_db()
            cast.endcastcal()
            cast.save()
            return HttpResponseRedirect("/wwdb/casts/%i/castenddetail" % cast.pk)
    context["form"] = form
    return render(request, "wwdb/casts/castend.html", context)

我期待在填充最后一个对象 enddate 字段时呈现“开始投射”按钮。当 enddate 字段为 none 时，“end cast”按钮应呈现。它目前呈现“结束投射”按钮，而不考虑最后一个对象的 enddate 字段值。