Optional and nullable fields in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to make the 'description' field optional in a FastAPI model.

FastAPI

from typing import [1]
from pydantic import BaseModel

class Item(BaseModel):
    name: str
    description: [1][str] = None

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

ASet

BList

COptional

DDict

Attempts:

3 left

💡 Hint

Common Mistakes

Using List or Dict instead of Optional

Not importing Optional from typing

Setting default to empty string instead of None

Using Optional from typing allows the field to be optional, meaning it can be None or a string.

2fill in blank

medium

Complete the code to allow the 'price' field to be nullable (accept None) in a FastAPI model.

FastAPI

from typing import Optional
from pydantic import BaseModel

class Product(BaseModel):
    name: str
    price: Optional[[1]] = None

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

Afloat

Bstr

Cint

Dbool

Attempts:

3 left

💡 Hint

Common Mistakes

Using int instead of float for price

Not setting default to None for nullable

Using str for price

The price field should be a float or None, so we use Optional[float].

3fill in blank

hard

Fix the error in the code to correctly declare an optional nullable field 'tags' as a list of strings.

FastAPI

from typing import [1], List
from pydantic import BaseModel

class BlogPost(BaseModel):
    title: str
    tags: [1][List[str]] = None

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

ACallable

BOptional

CAny

DUnion

Attempts:

3 left

💡 Hint

Common Mistakes

Using Union without specifying None

Using Any which is too broad

Not importing Optional

To make 'tags' optional and nullable, wrap the list type with Optional.

4fill in blank

hard

Fill both blanks to define a FastAPI model with an optional nullable 'rating' field of type float and a required 'title' field.

FastAPI

from typing import [1]
from pydantic import BaseModel

class Review(BaseModel):
    title: str
    rating: [2][float] = None

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

AOptional

BList

CDict

DSet

Attempts:

3 left

💡 Hint

Common Mistakes

Using different types for import and annotation

Using List or Dict instead of Optional

Not setting default to None

Both blanks use Optional to make the 'rating' field optional and nullable.

5fill in blank

hard

Fill all three blanks to create a FastAPI model with an optional nullable 'email' field of type string, a required 'username' field, and an optional nullable 'age' field of type int.

FastAPI

from typing import [1]
from pydantic import BaseModel

class User(BaseModel):
    username: str
    email: [2][str] = None
    age: [3][int] = None

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

AOptional

BList

DDict

Attempts:

3 left

💡 Hint

Common Mistakes

Using List or Dict instead of Optional

Not setting default to None

Mixing different types for optional fields

Use Optional for all optional nullable fields. Here, email and age are optional and nullable.