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Validation Guide ​

NyanSQLite leverages the powerful validation features of Pydantic v2.

When to Use Validation ​

Validation is useful when you want to:

  • Reject malformed records before saving them.
  • Maintain consistent data types within your database.
  • Automatically convert data passed as strings into appropriate types (e.g., int, datetime).

Automatic Validation via Pydantic ​

NyanSQLite automatically performs Pydantic validation during insertion and updates when you register() a class that inherits from BaseModel.

python
from pydantic import BaseModel, Field, EmailStr
from nyansqlite import NyanSQLite

class User(BaseModel):
    id: int
    name: str = Field(min_length=2)
    email: str # Requires pydantic[email] to use EmailStr
    age: int = Field(ge=0, le=150)

db = NyanSQLite("users.db")
db.register(User)

# OK
db.insert(User(id=1, name="Alice", email="[email protected]", age=30))

# Validation fails (raises Pydantic's ValidationError)
try:
    db.insert(User(id=2, name="A", email="invalid", age=-1))
except Exception as e:
    print(f"Validation failed: {e}")

Validation During update() ​

When using the update() method, the field values are also checked against the Pydantic model definition.

python
# Attempt to update age to an invalid value
try:
    db.update(User, where={"id": 1}, age=200) # Violates Field(le=150)
except Exception as e:
    print(f"Update failed: {e}")

Validating Complex Types ​

You can use the full power of Pydantic to safely store lists, dictionaries, enums, and more.

python
from typing import List, Dict
from enum import Enum

class Role(Enum):
    ADMIN = "admin"
    USER = "user"

class Profile(BaseModel):
    id: int
    roles: List[Role]
    metadata: Dict[str, str]

db.register(Profile)

# Automatically JSON serialized and deserialized back to original types
db.insert(Profile(
    id=1, 
    roles=[Role.ADMIN], 
    metadata={"login": "2024-01-01"}
))

Strict Deserialization (strict_deserialization) ​

When loading data from the database, you can control the behavior for corrupted data (e.g., malformed JSON) via the NyanSQLite constructor:

  • strict_deserialization=False (default): Emits a warning and returns raw data.
  • strict_deserialization=True: Raises a ValueError.
python
db = NyanSQLite("app.db", strict_deserialization=True)