How can I implement async validation in ASP.NET?

How can I implement async validation in ASP.NET?

You can implement async validation in ASP.NET by using the IAsyncValidator interface or by creating custom validation attributes that support asynchronous operations.

Can you give me an example of a custom async validation attribute?

Sure! Here's a simple example:

public class UniqueEmailAttribute : ValidationAttribute
{
    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        var email = value as string;
        // Simulate async database check
        var isUnique = CheckEmailAsync(email);
        return isUnique ? ValidationResult.Success : new ValidationResult("Email is already taken.");
    }
}

How do I call an async method inside the validation attribute?

You can use async and await in your validation logic. However, you need to ensure that your validation method returns a Task<ValidationResult> instead of ValidationResult.

What are some common pitfalls when using async validation?

Common pitfalls include not properly handling exceptions, blocking calls that can lead to deadlocks, and not considering the performance impact of multiple async calls.