How Can I Read Class Attributes at Runtime in C#?

Dynamically Accessing Class Attributes in C#

Accessing class attributes at runtime is a powerful technique for retrieving metadata or configuration information dynamically. This can be achieved using C#'s reflection capabilities.

Retrieving a Specific Attribute (DomainNameAttribute):

A generic method, GetDomainName<T>, simplifies retrieving a DomainNameAttribute from any class:

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

Usage example:

<code class="language-csharp">// Returns "MyTable" (assuming myclass has the attribute)
string domainName = GetDomainName<myclass>();</code>

A More General Approach for Attribute Access:

For broader applicability, a more generalized extension method allows retrieval of any attribute type and its specific property:

<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 attribute = type.GetCustomAttributes(typeof(TAttribute), true)
                            .FirstOrDefault() as TAttribute;
        return attribute != null ? valueSelector(attribute) : default(TValue);
    }
}</code>

Usage example:

<code class="language-csharp">string name = typeof(MyClass).GetAttributeValue((DomainNameAttribute dna) => dna.Name);</code>

This method takes the attribute type, and a lambda expression to select the desired property value from the attribute instance. This provides flexibility for accessing various attribute properties.

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