Entity Framework
Najlepsze praktyki dla Entity Framework (prosty i profesjonalny)

Wprowadzenie

1- Entity Framework @ Warstwa danych (podstawy)

W tym artykule wykorzystamy prostą bazę danych o nazwie „Firma” z dwiema tabelami:

[dbo]. [Categories] ([CategoryID], [CategoryName])

[dbo]. [Produkty] ([ProductID], [CategoryID], [ProductName])

1-1 Wygeneruj kod Entity Framework

W tej warstwie generujemy kod Entity Framework (w bibliotece projektu) (zobacz w tym artykule, jak to zrobić), a następnie będziesz mieć następujące klasy

public partial class CompanyContext : DbContext
public partial class Product
public partial class Category

1-2 Utwórz podstawowy interfejs

Stworzymy jeden interfejs dla naszych podstawowych funkcji

public interface IDbRepository : IDisposable
{
    #region Tables and Views functions

    IQueryable<TResult> GetAll<TResult>(bool noTracking = true) where TResult : class;
    TEntity Add<TEntity>(TEntity entity) where TEntity : class;
    TEntity Delete<TEntity>(TEntity entity) where TEntity : class;
    TEntity Attach<TEntity>(TEntity entity) where TEntity : class;
    TEntity AttachIfNot<TEntity>(TEntity entity) where TEntity : class;

    #endregion Tables and Views functions

    #region Transactions Functions

    int Commit();
    Task<int> CommitAsync(CancellationToken cancellationToken = default(CancellationToken));

    #endregion Transactions Functions

    #region Database Procedures and Functions

    TResult Execute<TResult>(string functionName, params object[] parameters);

    #endregion Database Procedures and Functions
}

1-3 Wdrażanie podstawowego interfejsu

/// <summary>
/// Implementing basic tables, views, procedures, functions, and transaction functions
/// Select (GetAll), Insert (Add), Delete, and Attach
/// No Edit (Modify) function (can modify attached entity without function call)
/// Executes database procedures or functions (Execute)
/// Transaction functions (Commit)
/// More functions can be added if needed
/// </summary>
/// <typeparam name="TEntity">Entity Framework table or view</typeparam>
public class DbRepository : IDbRepository
{
    #region Protected Members

    protected DbContext _dbContext;

    #endregion Protected Members

    #region Constractors

    /// <summary>
    /// Repository constructor 
    /// </summary>
    /// <param name="dbContext">Entity framework databse context</param>
    public DbRepository(DbContext dbContext)
    {
        _dbContext = dbContext;

        ConfigureContext();
    }

    #endregion Constractors

    #region IRepository Implementation

    #region Tables and Views functions

    /// <summary>
    /// Query all
    /// Set noTracking to true for selecting only (read-only queries)
    /// Set noTracking to false for insert, update, or delete after select
    /// </summary>
    public virtual IQueryable<TResult> GetAll<TResult>(bool noTracking = true) where TResult : class
    {
        var entityDbSet = GetDbSet<TResult>();

        if (noTracking)
            return entityDbSet.AsNoTracking();

        return entityDbSet;
    }

    public virtual TEntity Add<TEntity>(TEntity entity) where TEntity : class
    {
        return GetDbSet<TEntity>().Add(entity);
    }

    /// <summary>
    /// Delete loaded (attached) or unloaded (Detached) entitiy
    /// No need to load object to delete it
    /// Create new object of TEntity and set the id then call Delete function
    /// </summary>
    /// <param name="entity">TEntity</param>
    /// <returns></returns>
    public virtual TEntity Delete<TEntity>(TEntity entity) where TEntity : class
    {
        if (_dbContext.Entry(entity).State == EntityState.Detached)
        {
            _dbContext.Entry(entity).State = EntityState.Deleted;
            return entity;
        }
        else
            return GetDbSet<TEntity>().Remove(entity);
    }

    public virtual TEntity Attach<TEntity>(TEntity entity) where TEntity : class
    {
        return GetDbSet<TEntity>().Attach(entity);
    }

    public virtual TEntity AttachIfNot<TEntity>(TEntity entity) where TEntity : class
    {
        if (_dbContext.Entry(entity).State == EntityState.Detached)
            return Attach(entity);

        return entity;
    }

    #endregion Tables and Views functions

    #region Transactions Functions

    /// <summary>
    /// Saves all changes made in this context to the underlying database.
    /// </summary>
    /// <returns>The number of objects written to the underlying database.</returns>
    public virtual int Commit()
    {
        return _dbContext.SaveChanges();
    }

    /// <summary>
    /// Asynchronously saves all changes made in this context to the underlying database.
    /// </summary>
    /// <param name="cancellationToken">A System.Threading.CancellationToken to observe while waiting for the task to complete.</param>
    /// <returns>A task that represents the asynchronous save operation.  The task result contains the number of objects written to the underlying database.</returns>
    public virtual Task<int> CommitAsync(CancellationToken cancellationToken = default(CancellationToken))
    {
        return _dbContext.SaveChangesAsync(cancellationToken);
    }

    #endregion Transactions Functions

    #region Database Procedures and Functions

    /// <summary>
    /// Executes any function in the context
    /// use to call database procesdures and functions
    /// </summary>>
    /// <typeparam name="TResult">return function type</typeparam>
    /// <param name="functionName">context function name</param>
    /// <param name="parameters">context function parameters in same order</param>
    public virtual TResult Execute<TResult>(string functionName, params object[] parameters)
    {
        MethodInfo method = _dbContext.GetType().GetMethod(functionName);

        return (TResult)method.Invoke(_dbContext, parameters);
    }

    #endregion Database Procedures and Functions

    #endregion IRepository Implementation

    #region IDisposable Implementation

    public void Dispose()
    {
        _dbContext.Dispose();
    }

    #endregion IDisposable Implementation

    #region Protected Functions

    /// <summary>
    /// Set Context Configuration
    /// </summary>
    protected virtual void ConfigureContext()
    {
        // set your recommended Context Configuration
        _dbContext.Configuration.LazyLoadingEnabled = false;
    }

    #endregion Protected Functions

    #region Private Functions

    private DbSet<TEntity> GetDbSet<TEntity>() where TEntity : class
    {
        return _dbContext.Set<TEntity>();
    }

    #endregion Private Functions

}

2- Entity Framework @ warstwa biznesowa

W tej warstwie napiszemy aplikację biznesową.

Zalecane jest dla każdego ekranu prezentacji, tworzysz interfejs biznesowy i klasę implementacji, które zawierają wszystkie wymagane funkcje dla ekranu.

Poniżej napiszemy przykład ekranu biznesowego dla produktu

/// <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
}

3- Korzystanie z warstwy biznesowej @ Warstwa prezentacji (MVC)

W tym przykładzie użyjemy warstwy biznesowej w warstwie prezentacji. I użyjemy MVC jako przykładu warstwy prezentacji (ale możesz użyć dowolnej innej warstwy prezentacji).

Najpierw musimy zarejestrować IoC (użyjemy Unity, ale możesz użyć dowolnego IoC), a następnie napisz naszą warstwę prezentacji

3-1 Zarejestruj typy Unity w MVC

3-1-1 Dodaj kopię zapasową NuGet „Unity bootstrapper dla ASP.NET MVC”

3-1-2 Dodaj UnityWebActivator.Start (); w pliku Global.asax.cs (funkcja Application_Start ())

3-1-3 Zmodyfikuj funkcję UnityConfig.RegisterTypes w następujący sposób

    public static void RegisterTypes(IUnityContainer container)
    {
        // Data Access Layer
        container.RegisterType<DbContext, CompanyContext>(new PerThreadLifetimeManager());
        container.RegisterType(typeof(IDbRepository), typeof(DbRepository), new PerThreadLifetimeManager());

        // Business Layer
        container.RegisterType<IProductBusiness, ProductBusiness>(new PerThreadLifetimeManager());

    }

3-2 Korzystanie z warstwy biznesowej @ Warstwa prezentacji (MVC)

public class ProductController : Controller
{
    #region Private Members

    IProductBusiness _productBusiness;

    #endregion Private Members

    #region Constractors

    public ProductController(IProductBusiness productBusiness)
    {
        _productBusiness = productBusiness;
    }

    #endregion Constractors

    #region Action Functions

    [HttpPost]
    public ActionResult InsertForNewCategory(string productName, string categoryName)
    {
        try
        {
            // you can use any of IProductBusiness functions
            var newProduct = _productBusiness.InsertForNewCategory(productName, categoryName);

            return Json(new { success = true, data = newProduct });
        }
        catch (Exception ex) 
        {   /* log ex*/
            return Json(new { success = false, errorMessage = ex.Message});
        }
    }

    [HttpDelete]
    public ActionResult SmartDeleteWithoutLoad(int productId)
    {
        try
        {
            // deletes product without load
            var deletedProduct = _productBusiness.DeleteWithoutLoad(productId);

            return Json(new { success = true, data = deletedProduct });
        }
        catch (Exception ex)
        {   /* log ex*/
            return Json(new { success = false, errorMessage = ex.Message });
        }
    }

    public async Task<ActionResult> SelectByCategoryAsync(int CategoryId)
    {
        try
        {
            var results = await _productBusiness.SelectByCategoryAsync(CategoryId);

            return Json(new { success = true, data = results },JsonRequestBehavior.AllowGet);
        }
        catch (Exception ex)
        {   /* log ex*/
            return Json(new { success = false, errorMessage = ex.Message },JsonRequestBehavior.AllowGet);
        }
    }
    #endregion Action Functions
}

4 - Entity Framework @ Unit Test Layer

W warstwie testu jednostkowego zwykle testujemy funkcje warstwy biznesowej. W tym celu usuniemy zależności warstwy danych (Entity Framework).

A teraz pytanie brzmi: jak mogę usunąć zależności Entity Framework, aby przeprowadzić jednostkowe testowanie funkcji warstwy biznesowej?

Odpowiedź jest prosta: zrobimy fałszywą implementację interfejsu IDbRepository, a następnie będziemy mogli przeprowadzić nasz test jednostkowy

4-1 Implementacja podstawowego interfejsu (fałszywa implementacja)

class FakeDbRepository : IDbRepository
{
    #region Protected Members

    protected Hashtable _dbContext;
    protected int _numberOfRowsAffected;
    protected Hashtable _contextFunctionsResults;

    #endregion Protected Members

    #region Constractors

    public FakeDbRepository(Hashtable contextFunctionsResults = null)
    {
        _dbContext = new Hashtable();
        _numberOfRowsAffected = 0;
        _contextFunctionsResults = contextFunctionsResults;
    }

    #endregion Constractors

    #region IRepository Implementation

    #region Tables and Views functions

    public IQueryable<TResult> GetAll<TResult>(bool noTracking = true) where TResult : class
    {
        return GetDbSet<TResult>().AsQueryable();
    }

    public TEntity Add<TEntity>(TEntity entity) where TEntity : class
    {
        GetDbSet<TEntity>().Add(entity);
        ++_numberOfRowsAffected;
        return entity;
    }

    public TEntity Delete<TEntity>(TEntity entity) where TEntity : class
    {
        GetDbSet<TEntity>().Remove(entity);
        ++_numberOfRowsAffected;
        return entity;
    }

    public TEntity Attach<TEntity>(TEntity entity) where TEntity : class
    {
        return Add(entity);
    }

    public TEntity AttachIfNot<TEntity>(TEntity entity) where TEntity : class
    {
        if (!GetDbSet<TEntity>().Contains(entity))
            return Attach(entity);

        return entity;
    }

    #endregion Tables and Views functions

    #region Transactions Functions

    
    public virtual int Commit()
    {
        var numberOfRowsAffected = _numberOfRowsAffected;
        _numberOfRowsAffected = 0;
        return numberOfRowsAffected;
    }

    public virtual Task<int> CommitAsync(CancellationToken cancellationToken = default(CancellationToken))
    {
        var numberOfRowsAffected = _numberOfRowsAffected;
        _numberOfRowsAffected = 0;
        return new Task<int>(() => numberOfRowsAffected);
    }

    #endregion Transactions Functions

    #region Database Procedures and Functions

    public virtual TResult Execute<TResult>(string functionName, params object[] parameters)
    {
        if (_contextFunctionsResults != null && _contextFunctionsResults.Contains(functionName))
            return (TResult)_contextFunctionsResults[functionName];

        throw new NotImplementedException();
    }

    #endregion Database Procedures and Functions

    #endregion IRepository Implementation

    #region IDisposable Implementation

    public void Dispose()
    {

    }

    #endregion IDisposable Implementation

    #region Private Functions

    private List<TEntity> GetDbSet<TEntity>() where TEntity : class
    {
        if (!_dbContext.Contains(typeof(TEntity)))
            _dbContext.Add(typeof(TEntity), new List<TEntity>());

        return (List<TEntity>)_dbContext[typeof(TEntity)]; 
    }

    #endregion Private Functions
}

4-2 Uruchom testowanie urządzenia

[TestClass]
public class ProductUnitTest
{
    [TestMethod]
    public void TestInsertForNewCategory()
    {
        // Initialize repositories
        FakeDbRepository _dbRepository = new FakeDbRepository();

        // Initialize Business object
        IProductBusiness productBusiness = new ProductBusiness(_dbRepository);

        // Process test method
        productBusiness.InsertForNewCategory("Test Product", "Test Category");

        int _productCount = _dbRepository.GetAll<Product>().Count();
        int _categoryCount = _dbRepository.GetAll<Category>().Count();

        Assert.AreEqual<int>(1, _productCount);
        Assert.AreEqual<int>(1, _categoryCount);
    }

    [TestMethod]
    public void TestProceduresFunctionsCall()
    {
        // Initialize Procedures / Functions result
        Hashtable _contextFunctionsResults = new Hashtable();
        _contextFunctionsResults.Add("GetProductsCategory", new List<GetProductsCategory_Result> { 
            new GetProductsCategory_Result() { ProductName = "Product 1", ProductID = 1, CategoryName = "Category 1" },
            new GetProductsCategory_Result() { ProductName = "Product 2", ProductID = 2, CategoryName = "Category 1" },
            new GetProductsCategory_Result() { ProductName = "Product 3", ProductID = 3, CategoryName = "Category 1" }});

        // Initialize repositories
        FakeDbRepository _dbRepository = new FakeDbRepository(_contextFunctionsResults);

        // Initialize Business object
        IProductBusiness productBusiness = new ProductBusiness(_dbRepository);

        // Process test method
        var results = productBusiness.GetProductsCategory(1);

        Assert.AreEqual<int>(3, results.Count());
    }
}