2-实体框架业务层

在这一层，我们将编写应用程序业务。

建议在每个演示文稿屏幕中创建包含屏幕所需功能的业务接口和实现类。

下面我们将以产品屏幕编写业务为例

/// <summary>
/// Contains Product Business functions
/// </summary>
public interface IProductBusiness
{
    Product SelectById(int productId, bool noTracking = true);
    Task<IEnumerable<dynamic>> SelectByCategoryAsync(int CategoryId);
    Task<Product> InsertAsync(string productName, int categoryId);
    Product InsertForNewCategory(string productName, string categoryName);
    Product Update(int productId, string productName, int categoryId);
    Product Update2(int productId, string productName, int categoryId);
    int DeleteWithoutLoad(int productId);
    int DeleteLoadedProduct(Product product);
    IEnumerable<GetProductsCategory_Result> GetProductsCategory(int categoryId);
}

/// <summary>
/// Implementing Product Business functions
/// </summary>
public class ProductBusiness : IProductBusiness
{
    #region Private Members

    private IDbRepository _dbRepository;

    #endregion Private Members

    #region Constructors

    /// <summary>
    /// Product Business Constructor
    /// </summary>
    /// <param name="dbRepository"></param>
    public ProductBusiness(IDbRepository dbRepository)
    {
        _dbRepository = dbRepository;
    }

    #endregion Constructors

    #region IProductBusiness Function

    /// <summary>
    /// Selects Product By Id
    /// </summary>
    public Product SelectById(int productId, bool noTracking = true)
    {
        var products = _dbRepository.GetAll<Product>(noTracking);

        return products.FirstOrDefault(pro => pro.ProductID == productId);
    }

    /// <summary>
    /// Selects Products By Category Id Async
    /// To have async method, add reference to EntityFramework 6 dll or higher
    /// also you need to have the namespace "System.Data.Entity"
    /// </summary>
    /// <param name="CategoryId">CategoryId</param>
    /// <returns>Return what ever the object that you want to return</returns>
    public async Task<IEnumerable<dynamic>> SelectByCategoryAsync(int CategoryId)
    {
        var products = _dbRepository.GetAll<Product>();
        var categories = _dbRepository.GetAll<Category>();

        var result = (from pro in products
                      join cat in categories
                      on pro.CategoryID equals cat.CategoryID
                      where pro.CategoryID == CategoryId
                      select new
                      {
                          ProductId = pro.ProductID,
                          ProductName = pro.ProductName,
                          CategoryName = cat.CategoryName
                      }
                              );

        return await result.ToListAsync();
    }

    /// <summary>
    /// Insert Async new product for given category
    /// </summary>
    public async Task<Product> InsertAsync(string productName, int categoryId)
    {
        var newProduct = _dbRepository.Add(new Product() { ProductName = productName, CategoryID = categoryId });

        await _dbRepository.CommitAsync();

        return newProduct;
    }

    /// <summary>
    /// Insert new product and new category
    /// Do many database actions in one transaction
    /// each _dbRepository.Commit(); will commit one transaction
    /// </summary>
    public Product InsertForNewCategory(string productName, string categoryName)
    {
        var newCategory = _dbRepository.Add(new Category() { CategoryName = categoryName });
        var newProduct = _dbRepository.Add(new Product() { ProductName = productName, Category = newCategory });

        _dbRepository.Commit();

        return newProduct;
    }

    /// <summary>
    /// Update given product with tracking
    /// </summary>
    public Product Update(int productId, string productName, int categoryId)
    {
        var product = SelectById(productId,false);
        product.CategoryID = categoryId;
        product.ProductName = productName;

        _dbRepository.Commit();

        return product;
    }

    /// <summary>
    /// Update given product with no tracking and attach function
    /// </summary>
    public Product Update2(int productId, string productName, int categoryId)
    {
        var product = SelectById(productId);
        _dbRepository.Attach(product);

        product.CategoryID = categoryId;
        product.ProductName = productName;

        _dbRepository.Commit();

        return product;
    }

    /// <summary>
    /// Deletes product without loading it
    /// </summary>
    public int DeleteWithoutLoad(int productId)
    {
        _dbRepository.Delete(new Product() { ProductID = productId });

        return _dbRepository.Commit();
    }

    /// <summary>
    /// Deletes product after loading it
    /// </summary>
    public int DeleteLoadedProduct(Product product)
    {
        _dbRepository.Delete(product);

        return _dbRepository.Commit();
    }

    /// <summary>
    /// Assuming we have the following procedure in database
    /// PROCEDURE [dbo].[GetProductsCategory] @CategoryID INT, @OrderBy VARCHAR(50)
    /// </summary>
    public IEnumerable<GetProductsCategory_Result> GetProductsCategory(int categoryId)
    {
        return _dbRepository.Execute<IEnumerable<GetProductsCategory_Result>>("GetProductsCategory", categoryId, "ProductName DESC");
    }

    #endregion IProductBusiness Function
}