A small validation library for .NET that uses a fluent interface and lambda expressions for building validation rules. Written by Jeremy Skinner (http://www.jeremyskinner.co.uk) and licensed under Apache 2.
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Install-Package FluentValidation
For ASP.NET MVC integration:
Install-Package FluentValidation.MVC5
using FluentValidation; public class CustomerValidator: AbstractValidator<Customer> { public CustomerValidator() { RuleFor(customer => customer.Surname).NotEmpty(); RuleFor(customer => customer.Forename).NotEmpty().WithMessage("Please specify a first name"); RuleFor(customer => customer.Discount).NotEqual(0).When(customer => customer.HasDiscount); RuleFor(customer => customer.Address).Length(20, 250); RuleFor(customer => customer.Postcode).Must(BeAValidPostcode).WithMessage("Please specify a valid postcode"); } private bool BeAValidPostcode(string postcode) { // custom postcode validating logic goes here } } Customer customer = new Customer(); CustomerValidator validator = new CustomerValidator(); ValidationResult results = validator.Validate(customer); bool validationSucceeded = results.IsValid; IList<ValidationFailure> failures = results.Errors;