Why should you care?

ShopNest image gallery should lazy-load heavy product media only when opened.

See it live — copy this example

Paste into a C# console or class library project and run dotnet run.

public interface IProductMedia { string LoadUrl(); }
public sealed class RealProductMedia : IProductMedia
{
    private readonly string _sku;
    public RealProductMedia(string sku) => _sku = sku;
    public string LoadUrl()
    {
        Console.WriteLine("loading from blob...");
        return $"https://cdn.shopnest/{_sku}.jpg";
    }
}
public sealed class LazyMediaProxy : IProductMedia
{
    private readonly string _sku;
    private IProductMedia? _real;
    public LazyMediaProxy(string sku) => _sku = sku;
    public string LoadUrl() => (_real ??= new RealProductMedia(_sku)).LoadUrl();
}

IProductMedia media = new LazyMediaProxy("HD-100");
Console.WriteLine("created");
Console.WriteLine(media.LoadUrl());

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• LazyMediaProxy delays RealProductMedia until LoadUrl.
• Same interface as the real subject.
• Virtual/protection proxies follow the same shape.

Practice next

1. Run and confirm loading prints only on LoadUrl.
2. Call LoadUrl twice; still one real instance.
3. Add an auth-checking protection proxy variant.
4. Cache the URL string after first load.
5. Throw if sku is null in the proxy.

Remember

Surrogate controls access. Same interface as real object. Lazy/protection/remote variants.

ShopNest lazy media proxy

Admin list creates proxies; bytes load on expand.

Outcome: List pages stay light.