ASP.NET MVC 範例專案「Suteki.Shop」分析：Model 與 Service 層擴充

Model 以 Linq to SQL Shop.dbml 為基礎，透過 partial class 於 Model 資料夾擴充領域邏輯。以 Product 為例：

DBML 定義屬性

private int _ProductId; private int _CategoryId; private string _Name;
private string _Description; private decimal _Price; private int _Position;
private int _Weight; private bool _IsActive; private string _UrlName;

Product.cs 擴充實作

public partial class Product : IOrderable, IActivatable, IUrlNamed {
  partial void OnNameChanging(string value) { value.Label("Name").IsRequired(); }
  partial void OnNameChanged() { UrlName = Name.ToUrlFriendly(); }
  partial void OnDescriptionChanging(string value) { value.Label("Description").IsRequired(); }

  public bool HasMainImage { get { return this.ProductImages.Count > 0; } }
  public Image MainImage { get { return HasMainImage ? this.ProductImages.InOrder().First().Image : null; } }
  public bool HasSize { get { return this.Sizes.Active().Count() > 0; } }
  public Size DefaultSize { get { if (this.Sizes.Count() == 0) throw new ApplicationException("Product has no default size"); return this.Sizes[0]; } }
  public string IsActiveAsString { get { return IsActive ? string.Empty : " Not Active"; } }
  public static Product DefaultProduct(int parentCategory, int position) {
    return new Product { ProductId = 0, CategoryId = parentCategory, Position = position };
  }
}

展示了 partial method 驗證、導航屬性封裝、介面實作與工廠方法等領域模型豐富技巧。