Question

Complete the models.py of the store app we created at class by defining the relationships below. You need to think about the most appropriate on_delete option for each relationship.

student submitted image, transcription available below

Category – Product: A category can have multiple products.

 Customer – Order: A customer can have multiple orders

 Order – OrderItem: an order can have multiple orderitems

 Product – OrderItem: a product can have (represented by) multiple orderitems

 Cart – CartItem: A cart can have multiple cartitems.

 Product – CartItem: A product can have (represented by) multiple cartitems.

Answer 1

In a Django store app, various models are connected through ForeignKey relationships with specific on_delete options. Usually, 'on_delete=models.CASCADE' is used where the deletion of one object necessitates the deletion of all related objects. However, for relationships with Products, 'on_delete' might be set to 'DO_NOTHING' or 'SET_NULL' to avoid deleting products when associated items are removed.

Step-by-step explanation:

When working with Django's models.py within your store app, it is crucial to establish relationships between models appropriately. For the relationships given, here is how you might structure your models using ForeignKey and selecting the correct on_delete options:

• Category – Product: Use a ForeignKey with on_delete=models.CASCADE because when a category is deleted, all products associated with it should also be removed.
• Customer – Order: Use a ForeignKey with on_delete=models.CASCADE. A customer's orders are usually not meaningful without the customer record.
• Order – OrderItem: Use a ForeignKey with on_delete=models.CASCADE to ensure that when an order is deleted, all associated order items are also deleted.
• Product – OrderItem: Use a ForeignKey with on_delete=models.DO_NOTHING or on_delete=models.SET_NULL, depending on business logic. Products might need to persist even when an OrderItem is deleted.
• Cart – CartItem: Use a ForeignKey with on_delete=models.CASCADE, similar to orders and order items.
• Product – CartItem: Again, you might use on_delete=models.SET_NULL or on_delete=models.DO_NOTHING, allowing products to remain even if a CartItem is removed.

Each ForeignKey relationship will need to be carefully considered within the context of your application. Consult your business requirements to make the best choice for the on_delete parameter.