How to read the Description attribute in C#

Here's an example using the Description attribute with an enum representing different types of vehicles:

using System.ComponentModel;

public enum VehicleType
{
    [Description("Compact Car")]
    Sedan,
    [Description("Large SUV")]
    SUV,
    [Description("Two-wheeled motor vehicle")]
    Motorcycle
}

To read the Description attribute, follow these steps:

1. Retrieve the enum's type (e.g., VehicleType).
2. Get information about the specific enum member (e.g., VehicleType.Sedan).
3. Access the Description attribute and fetch its value.

This can be written as a one-liner using reflection:

using System.ComponentModel;

var vehicle = VehicleType.Sedan;

var descriptionAttribute = vehicle.GetType()
    .GetMember(vehicle.ToString())[0]
    .GetCustomAttributes(typeof(DescriptionAttribute), inherit: false)[0] as DescriptionAttribute;

Console.WriteLine($"Selected vehicle type: {descriptionAttribute.Description}");

Output:

Selected vehicle type: Compact Car

Note: The above approach assumes that the Description attribute is present. If it's missing, an exception will be thrown, which we'll address later.

This technique can be extended to fetch any custom attribute, not just the Description attribute.

Creating the GetEnumDescription() Extension Method

Rather than repeatedly using reflection in your code, it's a good practice to create an extension method to simplify attribute retrieval:

using System.ComponentModel;

public static class DescriptionAttributeExtensions
{
    public static string GetEnumDescription(this Enum e)
    {
        var descriptionAttribute = e.GetType().GetMember(e.ToString())[0]
            .GetCustomAttributes(typeof(DescriptionAttribute), inherit: false)[0] 
            as DescriptionAttribute;

        return descriptionAttribute.Description;
    }
}

This makes it easier to use the Description attribute like this:

var vehicle = VehicleType.Sedan;
var description = vehicle.GetEnumDescription();

Console.WriteLine($"My preferred vehicle is: {description}");

Output:

My preferred vehicle is: Compact Car

Handling Missing Descriptions

If the Description attribute is missing, the above code will throw an exception.

There are a couple of ways to handle this:

1. Detect the error and throw a more informative exception.
2. Provide a default value if the Description attribute is absent.

Here’s an example of returning the enum's name if the Description attribute is not found:

public static string GetEnumDescriptionOrName(this Enum e)
{
    var name = e.ToString();
    var memberInfo = e.GetType().GetMember(name)[0];
    var descriptionAttributes = memberInfo.GetCustomAttributes(typeof(DescriptionAttribute), inherit: false);

    if (!descriptionAttributes.Any())
        return name;

    return (descriptionAttributes[0] as DescriptionAttribute).Description;
}

When the Description is on a Property or Class

You can also use the Description attribute on class properties or the class itself. Here’s an example of a Car class with both property and class-level Description attributes:

using System.ComponentModel;

[Description("A high-performance vehicle designed for speed")]
public class Car
{
    [Description("The model of the car")]
    public string Model { get; set; }

    [Description("The color of the car")]
    public string Color { get; set; }
}

To read the Description attribute of the class or its properties, use the following code:

Property:

var propertyAttribute = typeof(Car).GetMember(nameof(Car.Model))[0]
    .GetCustomAttributes(typeof(DescriptionAttribute), inherit: false)[0] 
    as DescriptionAttribute;

Console.WriteLine($"Car.Model description = {propertyAttribute.Description}");

Output:

Car.Model description = The model of the car

Class:

var classDescription = typeof(Car)
    .GetCustomAttributes(typeof(DescriptionAttribute), inherit: false)[0]
    as DescriptionAttribute;

Console.WriteLine($"Car class description = {classDescription.Description}");

Output:

Car class description = A high-performance vehicle designed for speed

Here is a collection of extension methods to retrieve the Description attribute for enums, properties, and classes:

using System;
using System.ComponentModel;
using System.Linq;

public static class DescriptionAttributeExtensions
{
    public static string GetEnumDescription(this Enum e)
    {
        var descriptionAttribute = e.GetType().GetMember(e.ToString())[0]
            .GetCustomAttributes(typeof(DescriptionAttribute), inherit: false)[0] 
            as DescriptionAttribute;

        return descriptionAttribute.Description;
    }

    public static string GetEnumDescriptionOrName(this Enum e)
    {
        var name = e.ToString();
        var memberInfo = e.GetType().GetMember(name)[0];
        var descriptionAttributes = memberInfo.GetCustomAttributes(typeof(DescriptionAttribute), inherit: false);

        if (!descriptionAttributes.Any())
            return name;

        return (descriptionAttributes[0] as DescriptionAttribute).Description;
    }

    public static string GetMemberDescription<T>(this T t, string memberName) where T : class
    {
        var memberInfo = t.GetType().GetMember(memberName)[0];
        var descriptionAttribute = memberInfo.GetCustomAttributes(typeof(DescriptionAttribute), inherit: false)[0] as DescriptionAttribute;
        return descriptionAttribute.Description;
    }

    public static string GetClassDescription<T>(this T t) where T : class
    {
        var descriptionAttribute = t.GetType().GetCustomAttributes(typeof(DescriptionAttribute), inherit: false)[0]
            as DescriptionAttribute;

        return descriptionAttribute.Description;
    }
}

This set of methods can be used to handle descriptions for enums, properties, and entire classes. You can easily modify these methods to work with other attribute types as well.