Aggregates and entities in Microservices - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define an aggregate root in a microservice.

Microservices

class Order([1]):
    def __init__(self, order_id):
        self.order_id = order_id
        self.items = []

Drag options to blanks, or click blank then click option'

AAggregateRoot

BEntity

CService

DRepository

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Entity' instead of 'AggregateRoot' causes loss of aggregate control.

Using 'Service' or 'Repository' confuses domain concepts with infrastructure.

The aggregate root controls the lifecycle of entities within it. Here, AggregateRoot is the correct base class.

2fill in blank

medium

Complete the code to add an entity inside an aggregate.

Microservices

class OrderItem:
    def __init__(self, product_id, quantity):
        self.product_id = product_id
        self.quantity = [1]

Drag options to blanks, or click blank then click option'

Aprice

Border_id

Cquantity

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning 'price' or 'status' instead of 'quantity' causes incorrect data storage.

Using 'order_id' here is wrong because it's not part of the item itself.

The quantity attribute stores how many units of the product are ordered.

3fill in blank

hard

Fix the error in the method that adds an entity to the aggregate.

Microservices

class Order:
    def __init__(self):
        self.items = []

    def add_item(self, item):
        if item.product_id not in [i.product_id for i in self.items]:
            self.items.[1](item)

Drag options to blanks, or click blank then click option'

Aextend

Bappend

Cinsert

Dremove

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'extend' causes an error because it expects an iterable.

Using 'remove' deletes items instead of adding.

The append method adds a single item to the list. Using 'extend' or 'insert' is incorrect here.

4fill in blank

hard

Fill both blanks to correctly check entity existence and update quantity.

Microservices

def update_item_quantity(self, product_id, quantity):
    for item in self.items:
        if item.[1] == product_id:
            item.[2] = quantity
            return True
    return False

Drag options to blanks, or click blank then click option'

Aproduct_id

Bquantity

Cstatus

Dorder_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'status' or 'order_id' causes wrong attribute access.

Mixing up the attributes leads to logic errors.

We compare product_id to find the item, then update its quantity.

5fill in blank

hard

Fill all three blanks to create a dictionary of product IDs and quantities from entities.

Microservices

def get_items_summary(self):
    return {item.[1]: item.[2] for item in self.items if item.[3] > 0}

Drag options to blanks, or click blank then click option'

Aproduct_id

Bquantity

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'status' instead of 'quantity' breaks the filter logic.

Mixing keys and values causes incorrect dictionary structure.

The dictionary maps product_id to quantity, filtering items with quantity > 0.