NopCommerce架构分析之(三)EntityFramework数据库初试化及数据操作

系统启动时执行任务：IStartupTask,启动时执行的任务主要是数据库的初始化和加载。

IStartupTask调用IEfDataProvider进行数据库的初始化。

IEfDataProvider,SqlCeDataProvider：获取数据连接工厂，不同类型数据库，连接工厂不同。

接口IStartupTask的实体类EfStartUpTask的实现如下：

public class EfStartUpTask : IStartupTask {  public void Execute()  {   var settings = EngineContext.Current.Resolve<DataSettings>();   if (settings != null && settings.IsValid())   {    var provider = EngineContext.Current.Resolve<IEfDataProvider>();    if (provider == null)     throw new NopException("No EfDataProvider found");    provider.SetDatabaseInitializer();   }  }  public int Order  {   //ensure that this task is run first   get { return -1000; }  } }

SqlCeInitializer，CreateCeDatabaseIfNotExists初始化数据库。

IDbContext，NopObjectContext系统数据库操作上下文。加载所有数据库映射类：EntityTypeConfiguration<TEntityType>。代码如下：

protected override void OnModelCreating(DbModelBuilder modelBuilder) {  //dynamically load all configuration  //System.Type configType = typeof(LanguageMap); //any of your configuration classes here  //var typesToRegister = Assembly.GetAssembly(configType).GetTypes()  var typesToRegister = Assembly.GetExecutingAssembly().GetTypes()  .Where(type => !String.IsNullOrEmpty(type.Namespace))  .Where(type => type.BaseType != null && type.BaseType.IsGenericType && type.BaseType.GetGenericTypeDefinition() == typeof(EntityTypeConfiguration<>));  foreach (var type in typesToRegister)  {  dynamic configurationInstance = Activator.CreateInstance(type);  modelBuilder.Configurations.Add(configurationInstance);  }  //...or do it manually below. For example,  //modelBuilder.Configurations.Add(new LanguageMap());  base.OnModelCreating(modelBuilder); } 

此方法是继承自DbContext。并在系统启动时调用，建立数据表与实体的对应关系。

在类型依赖注册类Nop.Web.Framework.DependencyRegistrar中实现数据库工厂的创建、数据库的加载。如下代码：

//data layer var dataSettingsManager = new DataSettingsManager(); var dataProviderSettings = dataSettingsManager.LoadSettings(); builder.Register(c => dataSettingsManager.LoadSettings()).As<DataSettings>(); builder.Register(x => new EfDataProviderManager(x.Resolve<DataSettings>())).As<BaseDataProviderManager>().InstancePerDependency(); builder.Register(x => (IEfDataProvider)x.Resolve<BaseDataProviderManager>().LoadDataProvider()).As<IDataProvider>().InstancePerDependency(); builder.Register(x => (IEfDataProvider)x.Resolve<BaseDataProviderManager>().LoadDataProvider()).As<IEfDataProvider>().InstancePerDependency(); if (dataProviderSettings != null && dataProviderSettings.IsValid()) {  var efDataProviderManager = new EfDataProviderManager(dataSettingsManager.LoadSettings());  var dataProvider = (IEfDataProvider)efDataProviderManager.LoadDataProvider();  dataProvider.InitConnectionFactory();  builder.Register<IDbContext>(c => new NopObjectContext(dataProviderSettings.DataConnectionString)).InstancePerHttpRequest(); } else {  builder.Register<IDbContext>(c => new NopObjectContext(dataSettingsManager.LoadSettings().DataConnectionString)).InstancePerHttpRequest(); } builder.RegisterGeneric(typeof(EfRepository<>)).As(typeof(IRepository<>)).InstancePerHttpRequest();