VLDT: High-Performance Data Validation for Python

VLDT is a Python library with a C++ core. It validates dataclasses and parses JSON and dictionaries with strict type checks.

Features

• Type validation for dataclass fields
• Field and model validators
• Async validation support
• Dict and JSON parsing
• Field aliases and custom serialization

Performance

Benchmark settings:

• iterations: 100
• records: 1000

Results (lower is better):

Operation	vldt (s)	pydantic (s)	vldt / pyd
Parse Dict	0.424	0.731	0.58x
Dump Dict	0.216	0.529	0.41x
Parse JSON	0.979	0.995	0.98x
Dump JSON	0.475	0.679	0.70x
Append To List	1.141	3.779	0.30x
Mixed Usage	3.843	6.412	0.60x

vldt is faster on every operation in this workload. Parse JSON is on par with pydantic-core, while Dict parsing/serialization and list construction are 30 to 70 percent faster.

The benchmark script is in load_test/load_test.py.

Installation

Install with pip:

pip install vldt

Basic Usage

from vldt import DataModel

class UserProfile(DataModel):
    username: str
    email: str
    age: int

profile = UserProfile(username="alice123", email="alice@example.com", age=28)
print(profile.username, profile.email, profile.age)

Defaults and Optional Fields

from vldt import DataModel
from typing import Optional

class UserProfile(DataModel):
    username: str
    email: str
    country: str = "USA"
    phone: Optional[str]

profile = UserProfile(username="bob", email="bob@example.com", phone=None)
print(profile.country)

Field Options

from vldt import DataModel, Field

class Order(DataModel):
    order_id: int
    status: str = Field(default="pending")

order = Order(order_id=101)
print(order.status)

Nested Models

from typing import Union, List, Optional
from vldt import DataModel

class Address(DataModel):
    street: str
    zipcode: Union[int, str]
    country: str = "USA"

class Order(DataModel):
    order_id: int
    items: List[str]
    shipping_address: Optional[Address] = None

address = Address(street="123 Main St", zipcode=90210)
order = Order(order_id=1001, items=["book", "pen"], shipping_address=address)
print(order.shipping_address.zipcode)