What is fluent validation?

What is fluent validation?

Fluent Validation is a validation library for . NET, used for building strongly typed validation rules for business objects. Fluent validation is one way of setting up dedicated validator objects, that you would use when you want to treat validation logic as separate from business logic.

How do you implement fluent validation?

Fluent validations uses lamba expressions to build validation rules. For small systems, I would recommend just using Data Annotations, because they’re so easy to set up. For larger, more complex systems, I would recommend separating the validation concern using validator objects with Fluent Validation.

What is fluent validation C#?

FluentValidation is a .NET library for building strongly-typed validation rules. It Uses a fluent interface and lambda expressions for building validation rules. It helps clean up your domain code and make it more cohesive, as well as giving you a single place to look for validation logic.

What is fluent validation in .NET core?

FluentValidation supports integration with ASP.NET Core 3.1 or ASP.NET Core running on . NET 5. Once enabled, MVC will use FluentValidation to validate objects that are passed in to controller actions by the model binding infrastructure. AspNetCore ). This method must be called directly after calling AddMvc .

How do you debug fluent validation?

There is no way to debug Fluent Validator code with Visual Studio tools. You need to comment the specific part of code (RuleFor) that you want to test. Keep doing it until all rules are tested. The current version of FluentValidation allows you to unit test your validators by using the TestValidate extension method.

Is fluent validation open source?

Fluent Validation is a popular open source library for solving complex validation requirements written by Jeremy Skinner. The Fluent Validation library uses a fluent interface and lambda expressions to allow you to write very readable and expressive validation rules.

What is fluent API C#?

Fluent API is an advanced way of specifying model configuration that covers everything that data annotations can do in addition to some more advanced configuration not possible with data annotations.

When should I use Fluent API?

Entity Framework Fluent API is used to configure domain classes to override conventions. EF Fluent API is based on a Fluent API design pattern (a.k.a Fluent Interface) where the result is formulated by method chaining. In Entity Framework Core, the ModelBuilder class acts as a Fluent API.

How is fluentvalidation used to validate an object?

I’m using FluentValidation to validate a collection inside of an object, comparing an element of the collection items to an element of the parent object. The goal output is to receive ValidationFailures for each failed item in the collection, not just to fail the collection.

How to create child collections in fluentvalidation 8?

For example: Alternatively, as of FluentValidation 8.5, you can also define rules for child collection elements in-line using the ChildRules method: You can optionally include or exclude certain items in the collection from being validated by using the Where method. Note this must come directly after the call to RuleForEach:

When to use predicate validator in custom validation?

The recommended way is to make use of the Predicate Validator to write a custom validation function, but you can also use the Custom method to take full control of the validation process. For these examples, we’ll imagine a scenario where you want to create a reusable validator that will ensure a List object contains fewer than 10 items.

Is there a way to manually create validationfailure instance?

This method allows you to manually create the ValidationFailure instance associated with the validation error. Usually, the framework does this for you, so it is more verbose than using Must.