django.db.utils.IntegrityError: UNIQUE constraint failed: store_wishlist.user_id

Question

I am working on ecommerce website. I wanted to implement wishlist function on my website. And, it is working if its the first time for user that is adding to the list. In the second time giving an error. What's the problem? Can someone please help me? views.py

def addWishlistView(request):
    data = json.loads(request.body)
    productId = data['productId']
    action = data['action']
    print('Action:', action)
    print('Product:', productId)
    user = request.user
    product = Product.objects.get(id=productId)

    if (Wishlist.objects.filter(user=user) and Wishlist.objects.filter(product=product)).exists():
        print("Item is exists")
    else:
        Wishlist.objects.create(user=user,product=product)

    return JsonResponse('Item was added', safe=False)

models.py

class Wishlist(models.Model):
    product = models.ForeignKey(Product, on_delete=models.SET_NULL, null=True, verbose_name="Название товара")
    user = models.OneToOneField(User, on_delete=models.CASCADE,null=True, blank=True)

script js

for (i = 0; i < wishlist.length; i++) {
    wishlist[i].addEventListener('click', function(){
        var productId = this.dataset.product
        var action = this.dataset.action

        
        
        if (user == 'AnonymousUser'){
            Console.log("Not logged in");
        }else{
            addToWishlist(productId, action)
        }
    })
}

function addToWishlist(productId, action){
    console.log('User is authenticated, sending data...')

        var url = '/add_wishlist/'

        fetch(url, {
            method:'POST',
            headers:{
                'Content-Type':'application/json',
                'X-CSRFToken':csrftoken,
            }, 
            body:JSON.stringify({'productId':productId, 'action':action})
        })
        
        .then((data) => {
            location.reload()
        })
}

Is the intention to allow a user to add multiple items to their Wishlist? — Iain Shelvington, Feb 24 '22 at 05:50

Iain Shelvington · Accepted Answer · 2022-02-24T06:08:31.453

0

Change Wishlist.user to a models.ForeignKey so that you can add multiple per user, you can add a unique constraint to the model to only allow a user to add a product one time using Meta.unique_together

class Wishlist(models.Model):
    product = models.ForeignKey(Product, on_delete=models.SET_NULL, verbose_name="Название товара")
    user = models.ForeignKey(User, on_delete=models.CASCADE)

    class Meta:
        unique_together = (
            ('user', 'product'),
        )

In your view you don't need your if block, you can use get_or_create to only create a new entry if one doesn't already exist

    Wishlist.objects.get_or_create(user=user, product=product)

To delete a product from a user's wishlist if it exists or not you can use the delete() method on a filtered queryset

    deleted = Wishlist.objects.filter(user=user, product=product).delete()
    if deleted == 0:
        # Can do something when nothing was deleted if you like

edited Feb 24 '22 at 06:08

answered Feb 24 '22 at 05:55

Iain Shelvington

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Wishlist.objects.get_or_create(user=user, product=product) – Behzod Urinov Feb 24 '22 at 06:05
I had a question about this. how to delete then. If It's exists, I need to delete the item. I have no idea without if – Behzod Urinov Feb 24 '22 at 06:06
I am sorry. But, Can I ask another question. I wanted to publish another question. It's saying that I need 90 minutes. How to know if the product is in wishlist while publishing? – Behzod Urinov Feb 24 '22 at 06:28
@BehzodUrinov how to know if a product is in __any__ wishlists? – Iain Shelvington Feb 24 '22 at 06:28
Yes, in my view I got all wishlist products that relate to this user. And, according to this, I want to know if the product in that while rendering products – Behzod Urinov Feb 24 '22 at 06:30
@BehzodUrinov you want to render a list of products and add an annotation to each one that says if it's in the current user's wishlist or not? – Iain Shelvington Feb 24 '22 at 06:38
Yes, I want to color a heart with red if it's in that – Behzod Urinov Feb 24 '22 at 07:00
@BehzodUrinov might be worth asking another question. This answer is starting to get a bit messy as it is and the annotation you want is a little bit complex – Iain Shelvington Feb 24 '22 at 07:06
I asked: Filter in the template if the product is in wishlist or no. Django ecommerce website – Behzod Urinov Feb 24 '22 at 07:17

django.db.utils.IntegrityError: UNIQUE constraint failed: store_wishlist.user_id

1 Answers1