Schemas

Purpose

Schemas define external and internal data contracts: - request payload validation - response shaping - contract stability across endpoints

Example

class UserCreate(BaseModel):
    email: EmailStr
    full_name: str = Field(min_length=2, max_length=255)

class UserRead(BaseModel):
    id: int
    email: EmailStr
    full_name: str
    is_active: bool
    model_config = ConfigDict(from_attributes=True)

DO

• Keep API schemas in module schemas.py.
• Use strict field constraints.
• Separate create/update/read schemas.

DON'T

• Reuse DB ORM classes as API schemas.
• Put business logic methods inside schemas.

Common Mistakes

• One giant schema used for create/update/read.
• Optional fields in create payloads without explicit reason.

When to Break the Rule

Temporary compatibility schemas are allowed during version migrations; add removal plan in PR.