Displaying contrast of a queryset

[Abdou KARAMBIZI]

Hello,

I have 2 models :

class Product(models.Model):
    product_id = models.AutoField(primary_key=True)
    product_name = models.CharField(max_length=200)
    price = models.IntegerField()
    image = models.ImageField(upload_to='images/products_images/',null=True,blank=True)
  

    def __str__(self):
        return self.product_name
   

class Task(models.Model):
    task_id = models.AutoField(primary_key=True)
    user = models.ForeignKey(User,on_delete = models.CASCADE)
    product = models.ForeignKey(Product,on_delete=models.CASCADE)
    performed_at = models.DateTimeField(auto_now_add=True)

    def __int__(self):
        return self.task_id

and I have following view with queryset  :

def product_task (request):
product = Task.objects.select_related().all()
for p in product:
print(p.product.product_name)

I want to get products don't appear in task model

[Muhammad Juwaini Abdul Rahman]

You're looking for `product`, but the model that you queried is `Task`.

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[Kelvin Macharia]

Before I share my thoughts here is a question for you. Where do you expect your product to be printed out? 

Here is what I think you should try out.

First, the source code looks correct to me. Your view only get triggered when you access the routes(url) pointing to this view via the browser and this doesn't rerun server to print result on your console so you won't see anything get printed on the console. I presume you could be thinking of running a django app like you do with ordinary python scripts, your right but django is a python framework which requires specifics configurations to get results.

To test your code and see products get printed out try this:

1. Use a template. Modify your view as follows:

def product_task(request):
products = Task.objects.select_related().all()
context = {'products': products}

return render(request, 'product-task.html', context)

Create the template, configure routes in urls.py to point to this view and access through browser. Remember to add dummy data in your db

2. To print out your products using a for loop, use the django shell using 'python manage.py shell'

e.g.

(.venv) 
python manage.py shell
Python 3.12.2 (tags/v3.12.2:6abddd9, Feb  6 2024, 21:26:36) [MSC v.1937 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from stores.models import Task, Product
>>> products = Task.objects.select_related().all()
>>> for p in products:                                      
...     print(p.product.product_name)
...
Coffee
Banana Bread

Note: 

1. Stores refers to a dummy app I have created to host models.py. 

2. Coffee and Banana Bread are just products I have added as dummy data.

Hopes this help or atleast gives a guide somehow

[Abdou KARAMBIZI]

Hello friends,

products = Task.objects.select_related().all()
for p in products:                                      

print(p.product.product_name)

This gives product that has relation in Task model but I need product which doesn't have relation in Task 

Means we have products have relations in Task model and others with no relation in Task model and I need a queryset to display those with no relations in Task 

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[manohar chundru]

print(p)

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[Kelvin Macharia]

Hi  Abdou KARAMBIZI,

Have you tried to make the product field in the Task model optional?

Like:

product = models.ForeignKey(Product, on_delete=models.CASCADE, null=True, blank=True)

[Ryan Nowakowski]

Products.objects.filter(task_set__isnull=True)

[Kelvin Macharia]

Actually:

Query for tasks without relations to Product

tasks = Task.objects.filter(product__isnull=True)

after setting product field optional in as follows:

product = models.ForeignKey(Product, on_delete=models.CASCADE, null=True, blank=True)

[Abdou KARAMBIZI]

Thanks

Kelvin Macharia 

Now it is working properly 

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[Abdou KARAMBIZI]

  Hello,

I have 2 models :

class Product(models.Model):
    product_id = models.AutoField(primary_key=True)
    product_name = models.CharField(max_length=200)
    price = models.IntegerField()
    image = models.ImageField(upload_to='images/products_images/',null=True,blank=True)
  

    def __str__(self):
        return self.product_name
   

class Task(models.Model):
    task_id = models.AutoField(primary_key=True)
    user = models.ForeignKey(User,on_delete = models.CASCADE)
    product = models.ForeignKey(Product,on_delete=models.CASCADE)
    performed_at = models.DateTimeField(auto_now_add=True)

    def __int__(self):
        return self.task_id

 I want all products that a user logged in didn't send in task model

The following query is working but  when a user logs in should get all products he/she didn't send in task model

product = models.ForeignKey(Product, on_delete=models.CASCADE, null=True, blank=True)

tasks = Task.objects.filter(product__isnull=True)

[Natraj Kavander]

Thank you 

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