如何過濾兩個模型之間的差異？ 使用 django

Question

我有 2 個模型， Product和ProductRelatedGroupAndProduct ， Product有 5 個數據，[chicken, okra, ampalaya, cabbage] 和ProductRelatedGroupAndProduct有 [chicken, okra, cabbage] 如何獲取Product中沒有的剩余數據ProductRelatedGroupAndProduct ？

選擇的產品是ProductRelatedGroupAndProduct ，產品列表是Product

我只想讓所選產品上顯示的數據不再顯示在產品列表中。

到目前為止，這是我的 views.py

def searchrelatedproduct(request):
    id = request.GET.get('relatedproductID')
    products = Product.objects.all()
    relatedproduct = ProductRelatedGroupAndProduct.objects.filter(productrelatedgroup = id)
    return render(request, "customAdmin/relatedproduct.html",{"products":products,"relatedproduct":relatedproduct})

這是我的 html

<div class="container">
    <form method="POST" action="/GroupOfProduct/" enctype="multipart/form-data">{% csrf_token %}
  <h2>Product </h2>
    <div class="form-group">
      <br>
      <label for="sel2">List Of Products</label>
            <select multiple class="form-control" id="sel2" name="product">
                {% for product in products %}
                    <option>{{product.product}}</option>
                {% endfor %}
            </select>
    </div>
      <input type="submit" style="float:right;">
  </form>
</div>


<div class="container">
  <h2>Choosen Product</h2>
  <form method="POST" action="/UpdateGroupOfProduct/" enctype="multipart/form-data">{% csrf_token %}
      <input type="submit" style="float:right;">
    <div class="form-group">
      <br>
      <label for="sel2">List Of Choosen Products</label>
        <select multiple class="form-control" id="sel2" name="relatedproduct">
          {% for product in relatedproduct %}

            <option value="{{ product.id }}">{{product.product}}</option>
          {% endfor %}
        </select>
    </div>

  </form>
</div>

這是我的模型.py

class ProductRelatedGroupAndProduct(models.Model):
    product = models.ForeignKey(Product,on_delete=models.SET_NULL, null=True,blank=True,verbose_name="Product")
   productrelatedgroup = models.ForeignKey('ProductGroup',
                            on_delete=models.SET_NULL, null=True, blank=True,
                            verbose_name="ProductGroup")
class Product(models.Model):
    product = models.CharField(max_length=500)


class ProductGroup(models.Model):

    category = models.CharField(max_length=500, blank=True)

更新

當我嘗試這個

diffproducts = products.exclude(pk__in=relatedproduct)
print(diffproducts)

它打印產品的所有數據

<QuerySet [<Product: cabbage>, <Product: ampalaya>, <Product: okra>, <Product: Chicken>]>

當我嘗試這個時

unused_product = set(relatedproduct).difference(set(products))
print(unused_product)

***result***
{<ProductRelatedGroupAndProduct: cabbage>, <ProductRelatedGroupAndProduct: ampalaya>, <ProductRelatedGroupAndProduct: okra>}

還有這個

Product.objects.filter(productrelatedgroupandproduct__isnull=True)

我收到這個錯誤

django.core.exceptions.FieldError: Cannot resolve keyword 'productrelatedgroupandproduct' into field

Answer 1

您可以對過濾器使用反向關系：

Product.objects.filter(productrelatedgroupandproduct__isnull=True)

此處的productrelatedgroupandproduct是ProductRelatedGroupAndProduct model的小寫名稱。它是 related_query_name 參數的默認值。

Answer 2

這可以通過將查詢集轉換為集合然后對復雜情況使用intersection來實現。

# get objects present in both
set(products).intersection(set(relatedproduct))


# get product not in relatedproduct
set(products).difference(set(relatedproduct))


# opposite
set(relatedproduct).difference(set(products))

在您的情況下， exclude可以解決問題： products.exclude(pk__in=relatedproduct)

Answer 3

您可以使用排除 function：

意見.py：

def searchrelatedproduct(request):
    id = request.GET.get('relatedproductID')
    products = Product.objects.all()
    relatedproduct = ProductRelatedGroupAndProduct.objects.filter(pk=id)
    diffproducts = products.exclude(pk__in=relatedproduct)

    return render(request, "test.html",{"products":diffproducts,"relatedproduct":relatedproduct})

和原始 html 中的模板中的 output。