TooManyDataAnnotations 0.1.0

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TooManyDataAnnotations 🎯

Extending .NET's System.ComponentModel.DataAnnotations with powerful, semantic validation attributes.

💡 Tip: Check the NuGet page

📖 About

TooManyDataAnnotations is a collection of custom validation attributes designed to fill the gaps in .NET's built-in DataAnnotations library. While Microsoft provides basic validators (EmailAddress, Url, Range), they lack semantic validations for modern development needs like IPv4/IPv6, Semantic Versioning, MAC Addresses, ISO 8601 Dates, and more

This library provides production-ready, strongly-typed attributes that make your DTOs, models, and APIs self-documenting and robust

✨ Key Features

📦 Installation

dotnet add package TooManyDataAnnotations

🧩 Attributes by Category

🔢 Identifiers

Validates unique identifiers and URIs.

Example:

public class UserDto
{
    [GuidV7] // Only v7 allowed
    public string UserId { get; set; }

    [Uri(UriSchemes.Http | UriSchemes.Https)]
    public string Website { get; set; }
}

📝 Text

String formatting and content validation.

Example:

public class BlogPostDto
{
    [WebUrl(RequireHttps = true)]
    public string? FeaturedImage { get; set; }

    [Slug(AllowNumbers = true, RequireLowerCase = true)]
    public string TitleSlug { get; set; }

    [HexColor]
    public string AccentColor { get; set; } = "#6d4aff";
}

🌐 Network

IP addresses, MAC addresses, and port numbers

Enums Used:

• IPv4Scope: Public, LocalA, LocalB, LocalC, Private (= LocalA | LocalB | LocalC), Loopback, LinkLocal, Multicast, Reserved, All
• MacSeparators: Continuous (no separators), Colon, Dash, Dot, AnySeparator (= Colon | Dash | Dot), All
• PortRanges: WellKnown (0-1023), Registered (1024-49151), Dynamic (49152-65535)

Example:

public class NetworkConfigDto
{
    [IPv4(AllowedScopes = IPv4Scope.Private)]
    public string GatewayIP { get; set; }

    [IPv6(AllowIPv4Mapped = false)]
    public string PrimaryIPv6 { get; set; }

    [MacAddress(AllowedSeparators = MacSeparators.All)]
    public string AdapterMAC { get; set; }

    [PortNumber(AllowedRanges = PortRanges.Registered)]
    public int ApplicationPort { get; set; }
}

⏱️ Formatting

Dates, versions, and structured formats.

Examples:

public class ReleaseDto
{
    [SemanticVersion] // Validates "MAJOR.MINOR.PATCH[-PRE][+BUILD]"
    public string Version { get; set; }

    [IsoDateTime(RequireTime = true, AllowOffset = true)]
    public string PublishedAt { get; set; } // e.g., "2025-06-09T14:30:00Z"
}

🏗️ Classes

Validation rules applied to entire objects/classes

Note: RequiredAtLeastOne and ExactlyOneOf are convenience wrappers around RequiredAtLeastN (Minimum = 1) and ExactlyNOf (Count = 1) respectively, with simpler default error messages

Properties:

• CountEmptyStringsAsValue: If true, empty strings count as "provided". Default: false

Example:

[RequiredAtLeastOne(nameof(Email), nameof(Phone), nameof(SocialHandle))]
public class ContactInfoDto
{
    public string? Email { get; set; }
    public string? Phone { get; set; }
    public string? SocialHandle { get; set; }
}

[ExactlyOneOf(nameof(CreditCard), nameof(PayPal), nameof(BankTransfer))]
public class PaymentMethodDto
{
    public string? CreditCard { get; set; } // Provide EXACTLY ONE
    public string? PayPal { get; set; }
    public string? BankTransfer { get; set; }
}

🗓️ Temporal

Dates and specific points of time

Examples:

// By default, it will use "StartDate" and "EndDate" properties to validate
public class EventDto
{
    [StartDate] 
    public DateTime StartDate { get; set; }

    [EndDate]
    public DateTime EndDate { get; set; }
}

// Or you can specify your specific properties
public class EventDto
{
    [StartDate(nameof(MyEndTime))] 
    public DateTime MyStartTime { get; set; }

    [EndDate(nameof(MyStartTime))]
    public DateTime MyEndTime { get; set; }
}

⚡ Logical

Boolean validation rules — single values, collections, and class-level constraints

Note: AtLeastOneTrue and ExactlyOneTrue are convenience wrappers around MinimumTrueValues (Minimum = 1) and ExactlyNTrue (Count = 1) respectively, with simpler default error messages

🚀 Roadmap

What's coming next? (Priority order)

• [IsTrueAttribute] / [IsFalseAttribute] — Mandatory boolean flags
• [StartDateAttribute] / [EndDateAttribute] — Date range comparison
• [HashtagAttribute] — Social media hashtag format
• NuGet package publication
• Source Generator for AOT-compatible class-mode validation
• Additional attributes based on community feedback

🤝 Contributing

We welcome contributions! Please read our Contributor Guide before submitting PRs

How to Add a New Attribute

1. Follow the naming convention: <Name>Attribute.cs + <Name>Tests.cs
2. Place in appropriate folder (Network/, Text/, Classes/, etc.)
3. Use primary constructors where possible
4. Write comprehensive tests (null, empty, valid, invalid, options, edge cases)
5. Ensure all tests pass: dotnet test

See Code Conventions & Guidelines for detailed style rules

📄 License

This project is licensed under the MIT License. See LICENSE for details

👥 Acknowledgments

Created and maintained by LuisAlfredo92 with the help of Lumo AI Assistant

Built with ❤️ for the .NET community