How to Dynamically Read Attribute Values in C# at Runtime?

Read attribute values ​​dynamically at runtime

In software development, you often encounter situations where you need to dynamically access properties associated with a class or object. This capability is critical for various scenarios such as reflection, configuration retrieval, and dynamic code generation.

This article explores how to implement dynamic attribute retrieval in C#, demonstrating two different methods:

1. Custom methods for specific attribute types:

To read the attribute value of a specific attribute type, such as the DomainName attribute, you can define a custom method like this:

<code class="language-csharp">public string GetDomainName<T>()
{
    var dnAttribute = typeof(T).GetCustomAttributes(
        typeof(DomainNameAttribute), true
    ).FirstOrDefault() as DomainNameAttribute;
    if (dnAttribute != null)
    {
        return dnAttribute.Name;
    }
    return null;
}</code>

2. Generic extension methods for any property type:

To make the property retrieval process general and support any property type, you can create the following generic extension method:

<code class="language-csharp">public static class AttributeExtensions
{
    public static TValue GetAttributeValue<TAttribute, TValue>(
        this Type type,
        Func<TAttribute, TValue> valueSelector)
        where TAttribute : Attribute
    {
        var att = type.GetCustomAttributes(
            typeof(TAttribute), true
        ).FirstOrDefault() as TAttribute;
        if (att != null)
        {
            return valueSelector(att);
        }
        return default(TValue);
    }
}</code>

Usage:

Both methods allow you to get the DomainName attribute value at runtime, like this:

<code class="language-csharp">// 使用自定义方法
string domainNameValue = GetDomainName<MyClass>();

// 使用扩展方法
string name = typeof(MyClass)
    .GetAttributeValue((DomainNameAttribute dna) => dna.Name);</code>

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