Custom Attributes in C#?

Real Use Cases

• Validation frameworks
• Logging metadata
• Role-based security
• API documentation metadata

Custom Attribute Example

[AttributeUsage(AttributeTargets.Property)]

public class RequiredAttribute : Attribute {}

Usage Example

public class Employee
{

[Required]

public string Name { get; set; }
}

Validation Logic

public static void Validate(object obj)
{
var properties = obj.GetType().GetProperties();
foreach (var prop in properties)
{
var isRequired = prop.GetCustomAttributes(typeof(RequiredAttribute), false).Any();
if (isRequired && prop.GetValue(obj) == null)

throw new Exception($"{prop.Name} is required");

}
}