Async-Validation for ASP .Net Core

This library enhances the default validation mechanism in ASP .Net Core by introducing asynchronous capabilities. It is primarily derived from the codebases of dotnet/aspnetcore and microsoft/referencesource, with modifications to support asynchronous operations while preserving the core functionalities. The AsyncParameterBinder, an extension of the traditional parameter binder, allows for asynchronous model binding through its BindModelAsync() method.

Synchronous validation is used as a fallback, when the asynchronous validators, DefaultAsyncModelValidatorProvider or AsyncDataAnnotationsModelValidatorProvider, do not yield any results, ensuring continuous validation functionality.

Usage

To utilize the Async-Validation library in your ASP .Net Core project, start by integrating it into your service collection within the Startup.cs file or wherever you configure your services.

public void ConfigureServices(IServiceCollection services)
{
    services.AddAsyncValidation();
}

Using the Async Validator

The library provides an asynchronous variant of the traditional Validator, enabling non-blocking validation of models. This is particularly useful in scenarios requiring database lookups or other I/O operations during validation.

Example

Here's a sample method demonstrating how to use the ValidateObjectAsync method from the async validator. This method is an asynchronous counterpart to the traditional Validator.ValidateObject method, offering the same interface with the added benefit of asynchronous execution.

public async Task SomeMethodAsync(MyModel model, CancellationToken ct = default)
{
    var context = new ValidationContext(model, serviceProvider: null, items: null);
    await Validator.ValidateObjectAsync(
        instance: model,
        validationContext: context,
        validateAllProperties: true,
        cancellationToken: ct
    );
    // Async versions are available for all other public 'Validator' methods as well
}

In this example, ValidateObjectAsync is used to asynchronously validate an instance of MyModel. This method takes into account all properties of the model for validation and supports cancellation through the CancellationToken.