django query set

STRUCTURE

        queryset = Customer.objects.all()
            |          |       |      |
            |          |       |      |_ Method [ .get(), .filter(), exclude() ]
         variable      |       |
                       |       |_ Model Objects 
                       |            Attribute
                       |
                       |_ Model Name        

(1)Returns all customers from customer table

customers = Customer.objects.all()

(2)Returns first customer in table

firstCustomer = Customer.objects.first()

(3)Returns last customer in table

lastCustomer = Customer.objects.last()

(4)Returns single customer by name

customerByName = Customer.objects.get(name='Peter Piper')

(5)Returns single customer by name

customerById = Customer.objects.get(id=4)

(6)Returns all orders related to customer (firstCustomer variable set above)

firstCustomer.order_set.all()

(7)Returns orders customer name: (Query parent model values)

order = Order.objects.first() 
parentName = order.customer.name

(8)Returns products from products table with value of "Out Door" in category attribute

products = Product.objects.filter(category="Out Door")

(9)Order/Sort Objects by id

leastToGreatest = Product.objects.all().order_by('id') 
greatestToLeast = Product.objects.all().order_by('-id') 

(10)Returns all products with tag of "Sports": (Query Many to Many Fields)

productsFiltered = Product.objects.filter(tags__name="Sports")

''' (11)Bonus Q: If the customer has more than 1 ball, how would you reflect it in the database? A: Because there are many different products and this value changes constantly you would most likly not want to store the value in the database but rather just make this a function we can run each time we load the customers profile '''

#Returns the total count for number of time a "Ball" was ordered by the first customer ballOrders = firstCustomer.order_set.filter(product__name="Ball").count()

Returns total count for each product orderd

allOrders = {}

for order in firstCustomer.order_set.all():
	if order.product.name in allOrders:
		allOrders[order.product.name] += 1
	else:
		allOrders[order.product.name] = 1

Returns: allOrders: {'Ball': 2, 'BBQ Grill': 1}

#RELATED SET EXAMPLE
class ParentModel(models.Model):
	name = models.CharField(max_length=200, null=True)

class ChildModel(models.Model):
	parent = models.ForeignKey(Customer)
	name = models.CharField(max_length=200, null=True)

parent = ParentModel.objects.first()
#Returns all child models related to parent
parent.childmodel_set.all()