Custom validators in FastAPI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the BaseModel class from Pydantic.

FastAPI

from pydantic import [1]

class User([1]):
    name: str

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

AField

BBaseModel

Cvalidator

DValidationError

Attempts:

3 left

💡 Hint

Common Mistakes

Importing Field instead of BaseModel

Trying to import validator for the model base

The BaseModel class is the base for creating data models in Pydantic, which FastAPI uses for validation.

2fill in blank

medium

Complete the code to create a custom validator method for the 'age' field.

FastAPI

from pydantic import BaseModel, validator

class User(BaseModel):
    age: int

    @validator('[1]')
    def check_age(cls, value):
        if value < 18:
            raise ValueError('Must be at least 18')
        return value

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

Apassword

Bname

Cemail

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different field name in the validator decorator

Forgetting to specify the field name

The validator decorator must specify the field name it validates, here 'age'.

3fill in blank

hard

Fix the error in the validator method name to correctly validate the 'email' field.

FastAPI

from pydantic import BaseModel, validator

class User(BaseModel):
    email: str

    @validator('[1]')
    def validate_email(cls, value):
        if '@' not in value:
            raise ValueError('Invalid email')
        return value

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

Aemail

Bvalidate_email

Ccheck_email

Demail_validator

Attempts:

3 left

💡 Hint

Common Mistakes

Using the method name instead of the field name in the decorator

Using a made-up field name

The validator decorator must use the field name 'email' to apply validation on that field.

4fill in blank

hard

Fill both blanks to create a validator that checks the 'password' field length is at least 8 characters.

FastAPI

from pydantic import BaseModel, validator

class User(BaseModel):
    password: str

    @validator('[1]')
    def [2](cls, value):
        if len(value) < 8:
            raise ValueError('Password too short')
        return value

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Apassword

Bcheck_password

Cvalidate_password

Dpassword_validator

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong field name in the decorator

Using an invalid method name

The validator decorator must specify the field 'password'. The method name can be any valid name, here 'check_password' is used.

5fill in blank

hard

Fill all three blanks to create a validator that ensures the 'username' field is lowercase and at least 3 characters.

FastAPI

from pydantic import BaseModel, validator

class User(BaseModel):
    username: str

    @validator('[1]')
    def [2](cls, value):
        if len(value) < [3]:
            raise ValueError('Username too short')
        return value.lower()

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

Ausername

Bvalidate_username

C3

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong field name in decorator

Setting incorrect minimum length

Using method names that don't match the field

The validator decorator targets 'username'. The method name is 'validate_username'. The minimum length is 3 characters.