FluentValidation 12.2.0

Prefix Reserved
.NET 8.0 This package targets .NET 8.0. The package is compatible with this framework or higher. 
dotnet add package FluentValidation --version 12.2.0
                    


                    

                
NuGet\Install-Package FluentValidation -Version 12.2.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="FluentValidation" Version="12.2.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="FluentValidation" Version="12.2.0" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="FluentValidation" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add FluentValidation --version 12.2.0
                    


                    

                
#r "nuget: FluentValidation, 12.2.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#:package FluentValidation@12.2.0
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=FluentValidation&version=12.2.0
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=FluentValidation&version=12.2.0
                    


                            Install as a Cake Tool

FluentValidation is validation library for .NET that uses a fluent interface and lambda expressions for building strongly-typed validation rules.

Supporting the project

If you use FluentValidation in a commercial project, please sponsor the project financially. FluentValidation is developed and supported by @JeremySkinner for free in his spare time and financial sponsorship helps keep the project going. You can sponsor the project via either GitHub sponsors or OpenCollective.

Example

With FluentValidation, you can define a class that inherits from AbstractValidator which contains the rules for a particular class. The example below shows how you could define rules for a Customer class, and then how to execute the validator.

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();

// Execute the validator.
ValidationResult results = validator.Validate(customer);

// Inspect any validation failures.
bool success = results.IsValid;
List<ValidationFailure> failures = results.Errors;

Full Documentation

Full documentation can be found at https://docs.fluentvalidation.net

Release Notes and Change Log

Release notes can be found on GitHub.

Product Compatible and additional computed target framework versions.
.NET net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 was computed.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

  • net8.0

    • No dependencies.

NuGet packages (4.3K)

Showing the top 5 NuGet packages that depend on FluentValidation:

Package Downloads
FluentValidation.DependencyInjectionExtensions

Dependency injection extensions for FluentValidation
FluentValidation.AspNetCore

AspNetCore integration for FluentValidation
Reo.Core.DataModels

Package Description
FastEndpoints

A light-weight REST Api framework for ASP.Net 8 and newer that implements REPR (Request-Endpoint-Response) Pattern.
Ocelot

Ocelot is an API gateway based on ASP.NET Core stack.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last Updated
12.2.0 68,976 10/10/2026
12.1.1 69,780,731 12/3/2025
12.1.0 10,407,607 11/3/2025
12.0.0 49,245,638 5/5/2025
12.0.0-preview1 459,844 1/2/2025
11.12.0 5,761,179 11/3/2025
11.11.0 112,433,869 11/16/2024
11.10.0 32,632,909 9/15/2024
11.9.2 40,011,235 6/10/2024
11.9.1 20,581,901 4/23/2024
11.9.0 46,685,268 12/21/2023
11.8.1 13,186,731 11/22/2023
11.8.0 13,056,893 10/19/2023
11.7.1 14,514,687 8/12/2023
11.7.0 183,968 8/11/2023
11.6.0 11,530,312 7/4/2023
11.5.2 24,325,239 4/7/2023
11.5.1 95,128,935 2/20/2023
11.5.0 4,448,060 2/13/2023
11.4.0 23,903,302 11/23/2022
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FluentValidation 12 is a major release. Please read the upgrade guide at https://docs.fluentvalidation.net/en/latest/upgrading-to-12.html

Full release notes can be found at https://github.com/FluentValidation/FluentValidation/releases