What are the best practices for using attributes in ASP.NET MVC?

What are the best practices for using attributes in ASP.NET MVC?

When using attributes in ASP.NET MVC, it's important to keep your code clean and maintainable. Here are some best practices:

1. Use built-in attributes whenever possible, like [Required] or [StringLength].
2. Create custom attributes for reusable validation logic.
3. Keep attribute logic simple and focused on a single responsibility.
4. Avoid overusing attributes; consider using Fluent Validation for complex scenarios.

Can you give an example of a custom attribute?

Sure! Here's a simple example of a custom validation attribute:

public class EvenNumberAttribute : ValidationAttribute
{
    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        if (value is int number && number % 2 == 0)
        {
            return ValidationResult.Success;
        }
        return new ValidationResult("The number must be even.");
    }
}

How do I apply this custom attribute to a model property?

You can apply the custom attribute to a model property like this:

public class MyModel
{
    [EvenNumber]
    public int MyEvenNumber { get; set; }
}

What should I avoid when using attributes?

Avoid using too many custom attributes on a single model, as it can lead to confusion and make the code harder to maintain. Also, steer clear of complex logic within attributes; keep them simple and focused.