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.
NuGet Packages
Install-Package FluentValidation
For ASP.NET Core integration:
Install-Package FluentValidation.AspNetCore
For legacy ASP.NET MVC/WebApi integration:
Install-Package FluentValidation.MVC5
Install-Package FluentValidation.WebApi
Example
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;