Project Description
A small validation library for .NET that uses a fluent interface and lambda expressions for building validation rules for your business objects.

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NuGet packages are available - the package IDs are FluentValidation, FluentValidation.MVC3 and FluentValidation.MVC4.

If you need signed binaries then use the NuGet packages FluentValidaiton-signed, FluentValidation.MVC3-signed and FluentValidation.MVC4-signed.

The main source code repository for this project is on GitHub although it is also mirrored to CodePlex.


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.Company).NotNull();
    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;


Supported By


Last edited Apr 29, 2013 at 4:29 PM by JeremyS, version 35