RuleValidator 1.0.1

RuleValidator

RuleValidator is a small, fluent validation helper for .NET that collects validation rules and executes them only when Validate() is called.

Features

• Fluent chaining of property rules: .Property(x ⇒ x.Name).ShouldNotBeNullOrEmpty().ShouldHaveMinLength(3)
• Deferred execution: register rules first, run them later via Validate() or Validate(obj)
• Configurable validation options (email regex, password rules) via Configure(...)
• Add custom validation rules with Custom(...) that receive the property value and the parent object

Quick usage

// configure validator
var validator = RuleValidation.RuleValidator.For(myObj)
    .Configure(cfg => {
        cfg.EmailRegex = @"^[^@\s]+@[^@\s]+\.[^@\s]+$";
        cfg.PasswordOption.MinLength = 8;
        cfg.PasswordOption.RequireSpecialCharacter = true;
    });

// add rules
validator.Property(x => x.Name)
    .ShouldNotBeNullOrEmpty()
    .ShouldHaveMinLength(3)
    .ShouldHaveMaxLength(50);

validator.Property(x => x.Email)
    .ShouldNotBeNullOrEmpty()
    .ShouldBeEmail();

// run validation
var errors = validator.Validate();

Custom rule example

validator.Property(x => x.SomeValue)
    .Custom((val, parent) => {
        if (val == null) return "SomeValue is required";
        if ((int)val < parent.Minimum) return "SomeValue too small";
        return null;
    });

More Examples

1. Validate a property on a class instance (string length checks)

// MyDummyClass from tests
var obj = new MyDummyClass { Name = "John Doe" };
var validator = RuleValidator<MyDummyClass>.For(obj);
validator.Property(x => x.Name)
    .ShouldHaveMaxLength(20)
    .ShouldHaveMinLength(8);

var errors = validator.Validate(); // expected: no errors

2. Validate a raw value (string)

// validate raw string values
var rawValidator = new RuleValidator<string>();
rawValidator.Property(x => x).ShouldNotBeNullOrEmpty();

var ok = rawValidator.Validate("Test");        // expected: no errors
var empty = rawValidator.Validate(string.Empty); // expected: 1 error for the root value

3. Validate numeric values (range checks)

var numValidator = new RuleValidator<int>();
numValidator.Property(x => x).ShouldBeInRange(10, 20);

var ok = numValidator.Validate(19); // expected: no errors
var bad = numValidator.Validate(21); // expected: 1 error

4. Validate boolean values

// RuleValidator correctly handles boolean properties
var boolObj = new { IsActive = true };
var boolValidator = RuleValidator.For(boolObj);
boolValidator.Property(x => x.IsActive).ShouldBeTrue();

boolValidator.Validate(); // expected: no errors

boolObj = new { IsActive = false };
boolValidator = RuleValidator.For(boolObj);
boolValidator.Property(x => x.IsActive).ShouldBeFalse();

var errors = boolValidator.Validate(); // expected: no errors

Tips and notes

• Configure the validator once (for things like email regex and password options) and reuse the configured RuleValidator where appropriate.
• Use .Custom(...) to implement rules that depend on multiple properties or external state; Custom receives the current property value and the parent object.