EnsureValidation 1.0.0

EnsureValidation

A lightweight, zero-reflection fluent validation library for .NET, designed for DDD domain entities and value objects.

Why EnsureValidation?

EnsureValidation embeds validation directly into your domain entities using a fluent DSL -- no separate validator classes, no reflection, no magic.

Quick Start

dotnet add package EnsureValidation

1. Define your entity

using EnsureValidation;

public class Customer : Notifiable<Customer>
{
    public string? Name { get; set; }
    public string? Email { get; set; }
    public int? Age { get; set; }

    protected override void OnValidate()
    {
        Ensure.That(Name, nameof(Name))
            .Required()
            .MinLength(3)
            .MaxLength(100);

        Ensure.That(Email, nameof(Email))
            .Required()
            .EmailAddress();

        Ensure.That(Age, nameof(Age))
            .Required()
            .Between(18, 120);
    }
}

2. Validate

var customer = new Customer { Name = "AB", Email = "invalid", Age = 15 };
customer.Validate();

if (customer.IsInvalid)
{
    foreach (var notification in customer.Notifications)
        Console.WriteLine($"{notification.Field}: {notification.Message}");
}

Available Validators

String

Required() MinLength(n) MaxLength(n) ExactLength(n) ExactTrimmedLength(n) Matches(regex) EmailAddress() Must(predicate)

Numeric (int, long, decimal, double)

Required() EqualTo(n) NotEqualTo(n) GreaterThan(n) GreaterThanOrEqualTo(n) LessThan(n) LessThanOrEqualTo(n) Between(min, max) Must(predicate)

Bool

Required() IsTrue() IsFalse() Must(predicate)

Guid

Required() NotEmpty() Must(predicate)

DateTime

Required() After(date) Before(date) Between(from, to) InTheFuture() InThePast() Must(predicate)

Enum

Required() InEnum() GreaterThan(value)

Object (nested validation)

Required() IsValid() Must(predicate)

Collection

Required() AreValid()

Internationalization (i18n)

Default messages are in English. Override them globally:

Messages.To = (methodName, args) => methodName switch
{
    nameof(Messages.Required) => $"{args[0]} is required.",
    nameof(Messages.MinLength) => $"{args[0]} must be at least {args[1]} characters.",
    // ... other messages
    _ => $"{args[0]} is invalid."
};

For Portuguese (pt-BR) messages, install the companion package:

dotnet add package EnsureValidation.PtBR

EnsureValidation.PtBR

The EnsureValidation.PtBR companion package provides:

• Default messages in Portuguese (pt-BR) — all built-in validation messages are automatically translated.
• Brazilian document validators — additional string validators for Cpf() and Cnpj().

dotnet add package EnsureValidation.PtBR

using EnsureValidation.PtBR;

// Apply pt-BR messages globally (call once at startup)
PtBRMessages.Configure();

// Cpf and Cnpj validators become available on string chains
Ensure.That(cpf, nameof(cpf)).Required().Cpf();
Ensure.That(cnpj, nameof(cnpj)).Required().Cnpj();

Nested Object Validation

public class Order : Notifiable<Order>
{
    public Customer? Customer { get; set; }
    public List<OrderItem>? Items { get; set; }

    protected override void OnValidate()
    {
        Ensure.ThatObject(Customer, nameof(Customer))
            .Required()
            .IsValid();

        Ensure.ThatCollection(Items, nameof(Items))
            .Required()
            .AreValid();
    }
}

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Write tests for your changes
4. Ensure all tests pass (dotnet test)
5. Submit a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.