如何过滤模型中的外键？

Question

我创建了两个模型，Porumbei 和 Perechi。 Porumbei的意思是鸽子，它可以是雄性或雌性，它们成对生活（Perechi）。下面是我的模型（部分）

class Gender(models.Model):
    sexul = models.CharField(max_length=20, null=False, blank=False)
    def __str__(self):
        return self.sexul


class Porumbei(models.Model):
    ....
    serie_inel = models.CharField(....)
    sex = models.ForeignKey(Gender, on_delete=models.CASCADE)
    ....

class Perechi(models.Model):
    ....
    mascul = models.ForeignKey(Porumbei, on_delete=models.CASCADE)
    femela = models.ForeignKey(Porumbei, on_delete=models.CASCADE)

My form:

class AdaugaPereche(forms.Form):
    boxa = forms.IntegerField(label="Boxa", min_value=1)
    sezon = forms.CharField(label="Sezon reproducere", initial=datetime.now().year)
    mascul = forms.ChoiceField(choices=Porumbei.objects.filter(sex__sexul="Mascul", perechi_masculi__isnull=True), label="Mascul")
    femela = forms.ChoiceField(choices=Porumbei.objects.filter(sex__sexul="Femelă", perechi_femele__isnull=True), label="Femela")
    serie_pui_1 = forms.CharField(label="Serie pui 1")
    serie_pui_2 = forms.CharField(label="Serie pui 2")
    culoare_pui_1 = forms.ChoiceField(choices=CuloriPorumbei.objects.all(), label="Culoare pui 1")
    culoare_pui_2 = forms.ChoiceField(choices=CuloriPorumbei.objects.all(), label="Culoare pui 2")
    data_imperechere = forms.DateField(label="Dată împerechere")
    primul_ou = forms.DateField(label="Primul ou")
    data_ecloziune = forms.DateField(label="Dată ecloziune")
    data_inelare = forms.DateField(label="Dată inelare")
    comentarii = forms.Textarea()

My view:

def perechenoua(request):
if request.method == "POST":
    form = AdaugaPereche(request.POST)
    if form.is_valid():
        form.save()
        return redirect("porumbei")
else:
    form = AdaugaPereche()
context = {
    'form': form
}
template = loader.get_template("adauga_pereche.html")
return HttpResponse(template.render(context, request))

The template:

<form method="post">{% csrf_token %}
    <div class="form-group row">
        <div class="col-sm-3">
            {{ form.boxa|add_class:"form-control" }}
        </div>
        <div class="col-sm-3">
            {{ form.sezon|add_class:"form-control" }}
        </div>
    </div>
    <div class="form-group row">
        <div class="col-sm-3">
            {{ form.mascul|add_class:"form-control custom-select d-block w-100" }}
        </div>
        <div class="col-sm-3">
            {{ form.femela|add_class:"form-control custom-select d-block w-100" }}
        </div>
    </div>
    <div class="form-group row">
        <div class="col-sm-3">
            {{ form.serie_pui_1|add_class:"form-control" }}
        </div>
        <div class="col-sm-3">
            {{ form.serie_pui_2|add_class:"form-control custom-select d-block w-100" }}
        </div>
     </div>
     <div class="form-group row">
         <div class="col-sm-3">
             {{ form.culoare_pui_1|add_class:"form-control custom-select d-block w-100" }}
         </div>
         <div class="col-sm-3">
             {{ form.culoare_pui_2|add_class:"form-control custom-select d-block w-100" }}
         </div>
     </div>
     <div class="form-group row">
         <div class="col-sm-3">
             {{ form.data_imperechere }}
         </div>
         <div class="col-sm-3">
             {{ form.primul_ou }}
         </div>
     </div>
     <div class="form-group row">
         <div class="col-sm-3">
             {{ form.data_ecloziune }}
         </div>
         <div class="col-sm-3">
             {{ form.data_inelare }}
         </div>
     </div>
     <div class="form-group row">
         <div class="col-sm-3">
             {{ form.comentarii }}
         </div>
     </div>
</form>

当我创建一个新的 Perechi(pair) 时，我想将字段 mascul 与 Porumbei(pigeons) 中的所有雄性进行排序，一旦它被添加到对中，下次添加要排除的雄性对时列出，因为它已经有对。与女性相同。我该如何实现？

Answer 1

您可以使用ForeignKey 的limit_choices_to 参数直接限制选择：

from django.db.models import Q

mascul = models.ForeignKey(Porumbei, on_delete=models.CASCADE,
   limit_choices_to=Q(sex__sexul="male",
   related_name="pairs_as_male"))

Here 的文档。

使用related_name还可以查询反向关系：

Porumbei.objects.filter(sex__sexul="male", pairs_as_male__isnull=True)

会给你尚未配对的雄鸽。