A small validation library for .NET that uses a fluent interface and lambda expressions for building validation rules.
FluentValidation can be installed using the Nuget package manager or the dotnet CLI.
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
FluentValidation |
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FluentValidation.AspNetCore |
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FluentValidation.Mvc5 |
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FluentValidation.WebApi |
using FluentValidation;
public class CustomerValidator: AbstractValidator<Customer> {
public CustomerValidator() {
RuleFor(x => x.Surname).NotEmpty();
RuleFor(x => x.Forename).NotEmpty().WithMessage("Please specify a first name");
RuleFor(x => x.Discount).NotEqual(0).When(x => x.HasDiscount);
RuleFor(x => x.Address).Length(20, 250);
RuleFor(x => x.Postcode).Must(BeAValidPostcode).WithMessage("Please specify a valid postcode");
}
private bool BeAValidPostcode(string postcode) {
// custom postcode validating logic goes here
}
}
var customer = new Customer();
var validator = new CustomerValidator();
ValidationResult results = validator.Validate(customer);
bool success = results.IsValid;
IList<ValidationFailure> failures = results.Errors;