如何过滤两个模型之间的差异？ 使用 django

Question

I have 2 models, Product and ProductRelatedGroupAndProduct , the Product have 5 data, [chicken, okra, ampalaya, cabbage] and the ProductRelatedGroupAndProduct have [chicken, okra, cabbage] how do i get the remaining data in Product that dont have in ProductRelatedGroupAndProduct ?

the choosen product is ProductRelatedGroupAndProduct and the list of product is Product

I just want that the data displayed on the choosen product should no longer be visible in the product list.

so far this is my 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})

this is my 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>

this is my models.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)

UPDATE

when i tried this

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

it prints all data of the Product

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

and when i tried this

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

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

and this

Product.objects.filter(productrelatedgroupandproduct__isnull=True)

i get this error

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

Answer 1

You can use reverse relation for filter:

Product.objects.filter(productrelatedgroupandproduct__isnull=True)

productrelatedgroupandproduct here is a lowercased name of ProductRelatedGroupAndProduct model. It's default value for related_query_name argument.

Answer 2

This could be possible by converting your queryset to a set and then use intersection for complex cases.

# 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))

In your case exclude can do the trick: products.exclude(pk__in=relatedproduct)

Answer 3

You can use the exclude function:

views.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})

and output in template in your orignal html.