Search  
Always will be ready notify the world about expectations as easy as possible: job change page
Apr 1

Fluent Validation in .NET Core

Fluent Validation in .NET Core
Source:
Views:
955

Fluent validation is a third party library for validating your models in .NET. It is totally free.

Why fluent validation?

If you already have used data annotation for validation, then you must be aware of validation in .NET. So you might be thinking why do we need fluent validation.

Fluent validation helps you to separate validation logic from your models. That makes you code clean. If you have complex validation logic, then you want to define it separately rather than making your model unreadable.

If you have small scale project and does not have complex validation logic, then using data annotation makes more sense.

You can use the hybrid validation, it is totally up to you and what suits you best. None of them is good or bad. It depends on your requirements.

Create a project or use existing one

We will create a .net core project with template .Net Core Web Api. If you have existing project (for practicing) , then it is good. Don’t waste your precious time on creating a new one.

.NET Core Web API

Folder structure

Folder structure

Model

// Models/Person.cs
public class Person
{
    public int Id { get; set; }
    public string ? Name { get; set; }
    public string? Email { get; set; }
    public int Age { get; set; }
}

Easiest way (Data annotation)

Data annotation is the easiest way to validate your models..Nothing is wrong with it. It is fast and well suited for small projects. You must be familiar it with. Below is the example of it.

// Models/Person.cs
public class Person
{
    public int Id { get; set; }
    [Required]
    [MaxLength(50)]
    public string ? Name { get; set; }
    [Required]
    [MaxLength(50)]
    public string? Email { get; set; }
    public int Age { get; set; }
}

Fluent Validation

Fluent validation is a third party library which is free. So you need to install it first.

install-package FluentValidation.AspNetCore

Remove all the data annotation from Person.cs (if you are using)

// Models/Person.cs

public class Person
{
    public int Id { get; set; }
    public string ? Name { get; set; }
    public string? Email { get; set; }
    public int Age { get; set; }
}

Validator

We will create a separate class PersonValidator inside Validators directory. There we will define all the validation logic.

Validators/PersonValidator.cs

// Validators/PersonValidator.cs

using FluentValidation;
using net9demo.Models;

namespace net9demo.Validators;

public class PersonValidator: AbstractValidator<Person>
{
    public PersonValidator()
    {
      RuleFor(person=>person.Name).NotNull().MaximumLength(50);
      RuleFor(person=>person.Email).NotNull().MaximumLength(50);
    }
}

These rules are self explanatory.

First & Second rule, Name will be not null and Maximum Length will be 50.

Program.cs

You need some configuration in Program.cs to make validation work.

builder.Services
.AddControllers()
.AddFluentValidation(fv=>fv.RegisterValidatorsFromAssemblyContaining<Person>());

Person Controller

// PersonController.cs
using Microsoft.AspNetCore.Mvc;
using net9demo.Models;

namespace net9demo.Controllers;

[Route("api/people")]
[ApiController]
public class PersonController
{
    [HttpPost]
    public IActionResult AddPerson(Person person )
    {
        try
        {
            return CreatedAtAction(nameof(AddPerson),person);
        }
        catch (Exception ex)
        {
         
            return StatusCode(StatusCodes.Status500InternalServerError, ex.Message);
        }
    }
}

Test with Swagger UI

Swagger request
Request

Swagger response
Response

Email validator

RuleFor(person=>person.Email).NotNull().MaximumLength(50).EmailAddress();

Regular Expression and custom message

RuleFor(person => person.Password)
.NotEmpty()
.NotNull()
.MaximumLength(20)
.Matches("^(?=.*\\d).*$")
.WithMessage("Password must contain numeric value");

For more detail please visit official docs of fluent validation.

Similar
Apr 25
Author: FeatBit
Follow me on Twitter, happy to take your suggestions on topics or improvements.IntroductionMany third-party feature flagging services are available, or your internal team could develop its own feature flag service. For those who prefer standardization, following the OpenFeature guidelines is...
Mar 29
Author: Colton
These interview questions range from basic to advanced .Net Core, and will assist you in preparing for interviews, revising quickly, and strengthening your technical skills.According to the Stackoverflow Survey 2020,.NET and.NET Core are the second and third most popular frameworks...
Feb 12
Author: Kartik
Application Insights - Telemetry1. How do I instrument (monitor/record/enabling to capture telemetry) an application?Autoinstrumentation - if you don’t have access to source codeYou only need to install the Application Insights SDK if: You require custom events and...
Sep 10, 2023
Author: Sriram Kumar Mannava
In a situation where we need to modify our API’s structure or functionality while ensuring that existing API clients remain unaffected, the solution is versioning.We can designate our current APIs as the older version and introduce all intended changes in...
Send message
Email
Your name
*Message


© 1999–2024 WebDynamics
1980–... Sergey Drozdov
Area of interests: .NET Framework | .NET Core | C# | ASP.NET | Windows Forms | WPF | HTML5 | CSS3 | jQuery | AJAX | Angular | React | MS SQL Server | Transact-SQL | ADO.NET | Entity Framework | IIS | OOP | OOA | OOD | WCF | WPF | MSMQ | MVC | MVP | MVVM | Design Patterns | Enterprise Architecture | Scrum | Kanban