famo-data-validator 0.1.6

Python data validation library with type hints and schema support

Famo Data Validator

Famo Data Validator is a Python library for validating dictionaries and lists of dictionaries using a schema-based approach. It supports default values, required fields, custom validation, and schema generation.

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Features

• Validate single objects or multiple objects (many=True)
• Built-in field types: CharField, IntegerField, EmailField, ListField
• Required fields and default values
• Custom validation support
• Generate schema dynamically for documentation
• Fully typed and IDE-friendly

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Installation

pip install famo-data-validator

Or install the latest version from GitHub:

pip install git+https://github.com/famo-codes/data-validator.git

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Examples

1. Single Object Validation

from data_validator.serializer import Serializer
from data_validator.fields import CharField, IntegerField, EmailField, ListField

class UserSerializer(Serializer):
    name = CharField(min_length=3, max_length=50, required=True)
    age = IntegerField(min_value=0, max_value=120, default=18)
    email = EmailField(required=True)
    tags = ListField(item_field=CharField(), min_length=1, default=[])
    status = CharField(choices=["active", "inactive"], default="active")

user_data = {"name": "Alice", "email": "[e-mail]", "tags": ["python"]}
serializer = UserSerializer(data=user_data)
serializer.is_valid(raise_exception=True)
print(serializer.validated_data)

Output:

{
    "name": "Alice",
    "age": 18,
    "email": "[e-mail]",
    "tags": ["python"],
    "status": "active"
}

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2. Multiple Objects Validation

users = [
    {"name": "Alice", "email": "[e-mail]", "tags": ["python"]},
    {"name": "Bob", "email": "[e-mail]", "tags": ["backend"]}
]

serializer_many = UserSerializer(data=users, many=True)
serializer_many.is_valid(raise_exception=True)
print(serializer_many.validated_data)

Output:

[
    {"name": "Alice", "age": 18, "email": "[e-mail]", "tags": ["python"], "status": "active"},
    {"name": "Bob", "age": 18, "email": "[e-mail]", "tags": ["backend"], "status": "active"}
]

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3. Generate Schema for Documentation

import json

schema = UserSerializer().get_schema()
print(json.dumps(schema, indent=4))

Sample Output:

{
    "name": {"type": "CharField", "required": True, "default": None, "min_length": 3, "max_length": 50},
    "age": {"type": "IntegerField", "required": True, "default": 18, "min_value": 0, "max_value": 120},
    "email": {"type": "EmailField", "required": True, "default": None},
    "tags": {"type": "ListField", "required": True, "default": [], "item_field": "<CharField instance>", "min_length": 1},
    "status": {"type": "CharField", "required": True, "default": "active", "choices": ["active", "inactive"]}
}

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4. Custom Validator Example

from data_validator.fields import IntegerField, ValidationError

class PositiveIntegerField(IntegerField):
    def validate(self, value, field_name=None):
        value = super().validate(value, field_name)
        if value <= 0:
            raise ValidationError({field_name: "Value must be positive"})
        return value

class ProductSerializer(Serializer):
    price = PositiveIntegerField(required=True)

product_data = {"price": 50}
serializer = ProductSerializer(data=product_data)
serializer.is_valid(raise_exception=True)
print(serializer.validated_data)

Output:

{"price": 50}

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5. Handling Validation Errors

invalid_data = {"name": "A", "email": "invalid_email"}
serializer = UserSerializer(data=invalid_data)

if not serializer.is_valid():
    print(serializer.errors)

Sample Output:

{
    "name": "Minimum length is 3",
    "email": "Invalid email address"
}

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License

MIT License

Copyright (c) 2025 Famo

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.