Geekeey.Request.Validation (2.0.0)

Published 2026-05-30 18:06:42 +00:00 by HeyGeekeey in geekeey/request

Setup this registry from the command line:

dotnet nuget add source --name geekeey --username your_username --password your_token

To install the package using NuGet, run the following command:

dotnet add package --source geekeey --version 2.0.0 Geekeey.Request.Validation

For more information on the NuGet registry, see the documentation.

Lightweight validation library for C# with composable validators, fluent rules, and structured validation results.

Features

Composable validators: Build validators by inheriting from Validator<T> and defining rules with RuleFor and RuleForEach.
Built-in and custom rules: Use helpers like NotEmpty, Length, Between, and Matches, or define custom predicates with Must.
Structured validation output: Each failure is returned as a Problem with a property path, message, severity, code, and attempted value.
Nested validation: Reuse validators for complex object graphs with SetValidator, including DI-based resolution.
Configurable paths: Rewrite or remove rule property paths when the reported path should differ from the CLR member path.

Getting Started

Install the NuGet package:

dotnet add package Geekeey.Request.Validation

You may need to add our NuGet feed to your nuget.config this can be done by running the following command:

dotnet nuget add source -n geekeey https://code.geekeey.de/api/packages/geekeey/nuget/index.json

Usage

using Geekeey.Request.Validation;

public sealed record Address(string? Street);

public sealed record CreateUserRequest(
  string? Name,
  int Age,
  Address? Address,
  IReadOnlyList<string> Tags);

public sealed class AddressValidator : Validator<Address>
{
  public AddressValidator()
  {
    RuleFor(address => address.Street)
      .NotEmpty();
  }
}

public sealed class CreateUserRequestValidator : Validator<CreateUserRequest>
{
  public CreateUserRequestValidator()
  {
    RuleFor(request => request.Name)
      .NotEmpty()
      .Length(2, 100)
      .WithCode("NAME_INVALID");

    RuleFor(request => request.Age)
      .Between(18, 120);

    RuleFor(request => request.Address)
      .SetValidator(new AddressValidator());

    RuleForEach(request => request.Tags)
      .NotEmpty()
      .WithSeverity(Severity.Warning);
  }
}

public sealed record LoginInput(string? Username);

public sealed record LoginRequest(LoginInput Input);

public sealed class LoginInputValidator : Validator<LoginInput>
{
  public LoginInputValidator()
  {
    RuleFor(input => input.Username)
      .NotEmpty();
  }
}

public sealed class LoginRequestValidator : Validator<LoginRequest>
{
  public LoginRequestValidator()
  {
    RuleFor(request => request.Input)
      .WithoutPropertyPath()
      .SetValidator(new LoginInputValidator());
  }
}

var validator = new CreateUserRequestValidator();
var validation = validator.Validate(new CreateUserRequest(
  Name: "",
  Age: 16,
  Address: new Address(""),
  Tags: ["", "admin"]));

foreach (var problem in validation.Problems)
{
  Console.WriteLine($"{problem.PropertyPath}: {problem.Message}");
}

The resulting Problem entries include full property paths like Address.Street and Tags[0], making it easy to surface validation errors back to callers or APIs.

If the validation path needs to differ from the CLR property path, use WithPropertyPath(...) for a custom transform or WithoutPropertyPath() to drop the current rule path entirely before nested paths are appended.