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pythonbeginner

Pydantic v2 Model Patterns

Define and validate data models with Pydantic v2 using field validators, computed fields, and serialization.

python
from pydantic import BaseModel, Field, field_validator, computed_field
from datetime import datetime

class User(BaseModel):
    name: str = Field(min_length=1, max_length=100)
    email: str
    age: int = Field(ge=0, le=150)
    created_at: datetime = Field(default_factory=datetime.now)

    @field_validator("email")
    @classmethod
    def validate_email(cls, v: str) -> str:
        if "@" not in v:
            raise ValueError("Invalid email address")
        return v.lower().strip()

    @computed_field
    @property
    def display_name(self) -> str:
        return f"{self.name} ({self.email})"

# Usage
user = User(name="Alice", email="ALICE@EXAMPLE.COM", age=30)
print(user.model_dump_json(indent=2))

Use Cases

  • API request/response models
  • Configuration parsing
  • Data transformation

Tags

#pydantic#validation#models#serialization

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