【源码解读(一)】EFCORE源码解读之创建DBContext查询拦截

引言

　　　　在网上很少看到有关于系统讲解EFCore源码的，可能大概也许是因为EFCore的源码总体是没有asp.net web的源码流程清晰，正如群友所说，EFCore的源码大致看起来有点凌乱，与其说凌乱，不如说是没有一个好的方向；然后昨天在群里有一个朋友再说，EfCore的拦截器如何注入Web的服务，以及EfCore如何自定义查询，我就看了一下EfCore的源码，在此之前我针对asp.net web 做了一个源码解读，有兴趣的朋友可以看前面的文章，也给别人说过啥时候讲解一下efcore的源码，刚好借助这么一个机会，讲一讲EfCore的源码，本篇文章作为一个开端，会呈现一下几点

　　　　一：首先是AbbDbContext里面做了什么。

　　　　二：DbContext的构造函数里面做了那些事情。

　　　　三：如何在EfCore的服务中获取到Web注入的服务的方式之一。

　　　　四：拦截查询的几种方式。

　　　　五：使用缓存查询方法提升性能。

　　　　六：如何托管EFCORE的IOC容器(和Web的IOC使用同一个)

　　　　以上作为本篇文章的所有内容，接下来，我们来开始讲解源码，动手实践。

AddDbContext

　　　　EfCore提供了AddDbContext，AddDbContextFactory，AddDbContextPool，AddPooledDbContextFactory这几种扩展方法，我们会依次讲解，首先会讲解AddDbContext，后续的文章会依次讲解其余的方法。话不多说，上源码。下面是AddDbContext的源码，提供了多种方法，但是最终都会调用到这里，第一个参数是一个设置OptionBuilder的委托，传入了ServiceProvider和OptionBuilder，第二，三个分别是DbContext和DBContextOption的生命周期。

　　　　在下面的代码，刚开始判断了如果DBContext的生命周期是单例，要将Option的生命周期也设置为单例，如果不设置为单例，就会出现错误，这个错误在之前讲解IOC的文章中，我记得也提到过，接下来判断设置Option的委托是否为null，如果不为null，那DBContext的构造函数是必须要有一个参数，所以下面调用了一个方法CheckContextConstructors。

 public static IServiceCollection AddDbContext<TContextService, TContextImplementation>(
     this IServiceCollection serviceCollection,
     Action<IServiceProvider, DbContextOptionsBuilder>? optionsAction,
     ServiceLifetime contextLifetime = ServiceLifetime.Scoped,
     ServiceLifetime optionsLifetime = ServiceLifetime.Scoped)
     where TContextImplementation : DbContext, TContextService
 {
     if (contextLifetime == ServiceLifetime.Singleton)
     {
         optionsLifetime = ServiceLifetime.Singleton;
     }

     if (optionsAction != null)
     {
         CheckContextConstructors<TContextImplementation>();
     }

     AddCoreServices<TContextImplementation>(serviceCollection, optionsAction, optionsLifetime);

     if (serviceCollection.Any(d => d.ServiceType == typeof(IDbContextFactorySource<TContextImplementation>)))
     {
         // Override registration made by AddDbContextFactory
         var serviceDescriptor = serviceCollection.FirstOrDefault(d => d.ServiceType == typeof(TContextImplementation));
         if (serviceDescriptor != null)
         {
             serviceCollection.Remove(serviceDescriptor);
         }
     }

     serviceCollection.TryAdd(new ServiceDescriptor(typeof(TContextService), typeof(TContextImplementation), contextLifetime));

     if (typeof(TContextService) != typeof(TContextImplementation))
     {
         serviceCollection.TryAdd(
             new ServiceDescriptor(
                 typeof(TContextImplementation),
                 p => (TContextImplementation)p.GetService<TContextService>()!,
                 contextLifetime));
     }

     return serviceCollection;
 }

 private static void CheckContextConstructors<TContext>()
     where TContext : DbContext
 {
     var declaredConstructors = typeof(TContext).GetTypeInfo().DeclaredConstructors.ToList();
     if (declaredConstructors.Count == 1
         && declaredConstructors[0].GetParameters().Length == 0)
     {
         throw new ArgumentException(CoreStrings.DbContextMissingConstructor(typeof(TContext).ShortDisplayName()));
     }
 }

　　　　在CheckContextConstructors，我们看到反射去获取DBContext的继承类，查找构造函数，并且参数如果是0就会报异常。接下来在往下走，调用了一个AddCoreServices的方法，在这个方法里，我们是将DBContextOptions的泛型和非泛型注入到容器里面去，其中有一个CreateDbContextOptions的方法，里面去new了一个DbContextOptionsBuilder类，然后调用了一个UseApplicationServiceProvider方法，

    private static void AddCoreServices<TContextImplementation>(
        IServiceCollection serviceCollection,
        Action<IServiceProvider, DbContextOptionsBuilder>? optionsAction,
        ServiceLifetime optionsLifetime)
        where TContextImplementation : DbContext
    {
        serviceCollection.TryAdd(
            new ServiceDescriptor(
                typeof(DbContextOptions<TContextImplementation>),
                p => CreateDbContextOptions<TContextImplementation>(p, optionsAction),
                optionsLifetime));

        serviceCollection.Add(
            new ServiceDescriptor(
                typeof(DbContextOptions),
                p => p.GetRequiredService<DbContextOptions<TContextImplementation>>(),
                optionsLifetime));
    }

    private static DbContextOptions<TContext> CreateDbContextOptions<TContext>(
        IServiceProvider applicationServiceProvider,
        Action<IServiceProvider, DbContextOptionsBuilder>? optionsAction)
        where TContext : DbContext
    {
        var builder = new DbContextOptionsBuilder<TContext>(
            new DbContextOptions<TContext>(new Dictionary<Type, IDbContextOptionsExtension>()));

        builder.UseApplicationServiceProvider(applicationServiceProvider);

        optionsAction?.Invoke(applicationServiceProvider, builder);

        return builder.Options;
    }

　　　　下面是一个UseApplicationServiceProvider的调用链，最终调用到了WithApplicationServiceProvider方法，可以看到是返回了一个CoreOptionsExtension，最终调用WithOptions添加到了DbContextOptionsBuilder里面去，上面的代码中，我们new了一个DbContextOptionsBuilder，里面传入了一个DbContextOptions，构造函数传入了new Dictionary<Type,IDbContextOptionsExtension>()，最终我们的CoreOptionsExtension会添加到我们传入的这个字典里，用来保存所有的IDbContextOptionsExtension，这个接口可以理解为，数据库Options的扩展，接口定义如下，Info是关于扩展的一些元数据信息，ApplyService方法，参数是一个IServiceCollection，这个方法是我们将我们要注入的服务注入到这个里面去，因为EfCore的IOC和Web的IOC是区分开的，所以使用了不同的IServiceCollection，虽然提供了UseApplicationServiceProvider和UseInternalServiceProvider方法，实际上并不能实现IOC接管，设计实在是鸡肋，待会到了DbContext的构造函数中我们会看到为什么说鸡肋。Validate方法则是验证当前扩展，例如你得这个实现里面有一些参数，是必须要配置，或者配置有一个规则，我们在这里验证我们的配置或者规则是否符合我们需要的数据，如果不符合，在这里可以直接抛出异常。

　　　　回到CreateDbContextOptions，此时我们可以确保我们的Option的Extension里面是有一个CoreOptionsExtension，接下来，判断有没有设置OptionsBuilder的委托，调用然后返回到AddDbContext。

 public new virtual DbContextOptionsBuilder<TContext> UseApplicationServiceProvider(IServiceProvider? serviceProvider)
     => (DbContextOptionsBuilder<TContext>)base.UseApplicationServiceProvider(serviceProvider);
  public virtual DbContextOptionsBuilder UseApplicationServiceProvider(IServiceProvider? serviceProvider)
      => WithOption(e => e.WithApplicationServiceProvider(serviceProvider));
    public virtual CoreOptionsExtension WithApplicationServiceProvider(IServiceProvider? applicationServiceProvider)
    {
        var clone = Clone();

        clone._applicationServiceProvider = applicationServiceProvider;

        return clone;
    }

  private DbContextOptionsBuilder WithOption(Func<CoreOptionsExtension, CoreOptionsExtension> withFunc)
  {
      ((IDbContextOptionsBuilderInfrastructure)this).AddOrUpdateExtension(
          withFunc(Options.FindExtension<CoreOptionsExtension>() ?? new CoreOptionsExtension()));

      return this;
  }

public interface IDbContextOptionsExtension
{
    /// <summary>
    ///     Information/metadata about the extension.
    /// </summary>
    DbContextOptionsExtensionInfo Info { get; }

    /// <summary>
    ///     Adds the services required to make the selected options work. This is used when there
    ///     is no external <see cref="IServiceProvider" /> and EF is maintaining its own service
    ///     provider internally. This allows database providers (and other extensions) to register their
    ///     required services when EF is creating an service provider.
    /// </summary>
    /// <param name="services">The collection to add services to.</param>
    void ApplyServices(IServiceCollection services);

    /// <summary>
    ///     Gives the extension a chance to validate that all options in the extension are valid.
    ///     Most extensions do not have invalid combinations and so this will be a no-op.
    ///     If options are invalid, then an exception should be thrown.
    /// </summary>
    /// <param name="options">The options being validated.</param>
    void Validate(IDbContextOptions options);
}

    void IDbContextOptionsBuilderInfrastructure.AddOrUpdateExtension<TExtension>(TExtension extension)
        => _options = _options.WithExtension(extension);

　　　　在AddDbContext的最后，这几行代码，是将我们的DbContext注入到我们的IOC容器中去。

if (serviceCollection.Any(d => d.ServiceType == typeof(IDbContextFactorySource<TContextImplementation>)))
{
    // Override registration made by AddDbContextFactory
    var serviceDescriptor = serviceCollection.FirstOrDefault(d => d.ServiceType == typeof(TContextImplementation));
    if (serviceDescriptor != null)
    {
        serviceCollection.Remove(serviceDescriptor);
    }
}

serviceCollection.TryAdd(new ServiceDescriptor(typeof(TContextService), typeof(TContextImplementation), contextLifetime));

if (typeof(TContextService) != typeof(TContextImplementation))
{
    serviceCollection.TryAdd(
        new ServiceDescriptor(
            typeof(TContextImplementation),
            p => (TContextImplementation)p.GetService<TContextService>()!,
            contextLifetime));
}

　　　　至此，关于AddDbContext的源码讲解完毕，接下来进到DbContext构造函数的源码讲解，这里设计内容稍微多一些。

DBContext构造

　　　　构造函数的代码是整体是没多少的，但是最重要的还是在于GetOrAdd的方法。所以这里我会只讲这个方法的内部

 public DbContext(DbContextOptions options)
 {
     Check.NotNull(options, nameof(options));

     if (!options.ContextType.IsAssignableFrom(GetType()))
     {
         throw new InvalidOperationException(CoreStrings.NonGenericOptions(GetType().ShortDisplayName()));
     }

     _options = options;

     // This service is not stored in _setInitializer as this may not be the service provider that will be used
     // as the internal service provider going forward, because at this time OnConfiguring has not yet been called.
     // Mostly that isn't a problem because set initialization is done by our internal services, but in the case
     // where some of those services are replaced, this could initialize set using non-replaced services.
     // In this rare case if this is a problem for the app, then the app can just not use this mechanism to create
     // DbSet instances, and this code becomes a no-op. However, if this set initializer is then saved and used later
     // for the Set method, then it makes the problem bigger because now an app is using the non-replaced services
     // even when it doesn't need to.
     ServiceProviderCache.Instance.GetOrAdd(options, providerRequired: false)
         .GetRequiredService<IDbSetInitializer>()
         .InitializeSets(this);

     EntityFrameworkEventSource.Log.DbContextInitializing();
 }

　　　　下面是ServiceProviderCache的全部源码，在GetOrAdd方法，先获取了CoreOptionsExtension，这个我们在AddDbContext的时候，已经添加过了，并且设置了ApplicationProvider，在往下走，判断InternalServiceProvider，这里我们没有设置，就会继续往下走，判断了一个ServiceProviderCachingEnabled 这个默认是true，然后下面获取CoreOptionsExtension的ApplicationServiceProvider，还记得我们在最初的时候AddDbContext的时候，创建DbContextOptionsBuilder的时候，我们UseApplicationServiceProvider方法，就是设置了一个公用的Provider，现在把他在设置为null，如果说这个Provider有啥作用，哈哈哈哈，我认为他就是创建Options的时候需要用，然后给一个有东西的不为空的CoreOptionsExtension，这个方法，实际上我觉得微软设置为internal最好了，这样可能会存在误解开发者，而InternalServiceProvider是很有用，可以和我们的web共用一个ioc容器，在本文的最后，我会将ef的ioc容器托管到web的。

　　　　ServiceProviderCachingEnabled参数代表是否将GetOrAdd通过BuildServiceProvider创建的ServiceProvider缓存到_configuration中去，不缓存的话，每次都是一个新的Provider，对性能有影响，如果缓存，则第一次创建后面都是从那里面取。

　　　　接下来就到了GetOrAdd最后，要调用BuildServiceProvider方法来创建一个ServiceProvider，下面的方法，我们着重看几个关键点一个是ApplyService，一个是new ServiceCollection(说明web的ioc和ef的ioc不是同一个)，ReplaceService。

public class ServiceProviderCache
{
    private readonly ConcurrentDictionary<IDbContextOptions, (IServiceProvider ServiceProvider, IDictionary<string, string> DebugInfo)>
        _configurations = new();

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public static ServiceProviderCache Instance { get; } = new();

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public virtual IServiceProvider GetOrAdd(IDbContextOptions options, bool providerRequired)
    {
        var coreOptionsExtension = options.FindExtension<CoreOptionsExtension>();
        var internalServiceProvider = coreOptionsExtension?.InternalServiceProvider;
        if (internalServiceProvider != null)
        {
            ValidateOptions(options);

            var optionsInitializer = internalServiceProvider.GetService<ISingletonOptionsInitializer>();
            if (optionsInitializer == null)
            {
                throw new InvalidOperationException(CoreStrings.NoEfServices);
            }

            if (providerRequired)
            {
                optionsInitializer.EnsureInitialized(internalServiceProvider, options);
            }

            return internalServiceProvider;
        }

        if (coreOptionsExtension?.ServiceProviderCachingEnabled == false)
        {
            return BuildServiceProvider(options, (_configurations, options)).ServiceProvider;
        }

        var cacheKey = options;
        var extension = options.FindExtension<CoreOptionsExtension>();
        if (extension?.ApplicationServiceProvider != null)
        {
            cacheKey = ((DbContextOptions)options).WithExtension(extension.WithApplicationServiceProvider(null));
        }

        return _configurations.GetOrAdd(
                cacheKey,
                static (contextOptions, tuples) => BuildServiceProvider(contextOptions, tuples), (_configurations, options))
            .ServiceProvider;

        static (IServiceProvider ServiceProvider, IDictionary<string, string> DebugInfo) BuildServiceProvider(
            IDbContextOptions _,
            (ConcurrentDictionary<IDbContextOptions, (IServiceProvider ServiceProvider, IDictionary<string, string> DebugInfo)>,
                IDbContextOptions) arguments)
        {
            var (configurations, options) = arguments;

            ValidateOptions(options);

            var debugInfo = new Dictionary<string, string>();
            foreach (var optionsExtension in options.Extensions)
            {
                optionsExtension.Info.PopulateDebugInfo(debugInfo);
            }

            debugInfo = debugInfo.OrderBy(_ => debugInfo.Keys).ToDictionary(d => d.Key, v => v.Value);

            var services = new ServiceCollection();
            var hasProvider = ApplyServices(options, services);

            var replacedServices = options.FindExtension<CoreOptionsExtension>()?.ReplacedServices;
            if (replacedServices != null)
            {
                var updatedServices = new ServiceCollection();
                foreach (var descriptor in services)
                {
                    if (replacedServices.TryGetValue((descriptor.ServiceType, descriptor.ImplementationType), out var replacementType))
                    {
                        ((IList<ServiceDescriptor>)updatedServices).Add(
                            new ServiceDescriptor(descriptor.ServiceType, replacementType, descriptor.Lifetime));
                    }
                    else if (replacedServices.TryGetValue((descriptor.ServiceType, null), out replacementType))
                    {
                        ((IList<ServiceDescriptor>)updatedServices).Add(
                            new ServiceDescriptor(descriptor.ServiceType, replacementType, descriptor.Lifetime));
                    }
                    else
                    {
                        ((IList<ServiceDescriptor>)updatedServices).Add(descriptor);
                    }
                }

                services = updatedServices;
            }

            var serviceProvider = services.BuildServiceProvider();

            if (hasProvider)
            {
                serviceProvider
                    .GetRequiredService<ISingletonOptionsInitializer>()
                    .EnsureInitialized(serviceProvider, options);
            }

            using (var scope = serviceProvider.CreateScope())
            {
                var scopedProvider = scope.ServiceProvider;

                // If loggingDefinitions is null, then there is no provider yet
                var loggingDefinitions = scopedProvider.GetService<LoggingDefinitions>();
                if (loggingDefinitions != null)
                {
                    // Because IDbContextOptions cannot yet be resolved from the internal provider
                    var logger = new DiagnosticsLogger<DbLoggerCategory.Infrastructure>(
                        ScopedLoggerFactory.Create(scopedProvider, options),
                        scopedProvider.GetRequiredService<ILoggingOptions>(),
                        scopedProvider.GetRequiredService<DiagnosticSource>(),
                        loggingDefinitions,
                        new NullDbContextLogger());

                    if (configurations.IsEmpty)
                    {
                        logger.ServiceProviderCreated(serviceProvider);
                    }
                    else
                    {
                        logger.ServiceProviderDebugInfo(
                            debugInfo,
                            configurations.Values.Select(v => v.DebugInfo).ToList());

                        if (configurations.Count >= 20)
                        {
                            logger.ManyServiceProvidersCreatedWarning(
                                configurations.Values.Select(e => e.ServiceProvider).ToList());
                        }
                    }

                    var applicationServiceProvider = options.FindExtension<CoreOptionsExtension>()?.ApplicationServiceProvider;
                    if (applicationServiceProvider?.GetService<IRegisteredServices>() != null)
                    {
                        logger.RedundantAddServicesCallWarning(serviceProvider);
                    }
                }
            }

            return (serviceProvider, debugInfo);
        }
    }

    private static void ValidateOptions(IDbContextOptions options)
    {
        foreach (var extension in options.Extensions)
        {
            extension.Validate(options);
        }
    }

    private static bool ApplyServices(IDbContextOptions options, ServiceCollection services)
    {
        var coreServicesAdded = false;

        foreach (var extension in options.Extensions)
        {
            extension.ApplyServices(services);

            if (extension.Info.IsDatabaseProvider)
            {
                coreServicesAdded = true;
            }
        }

        if (coreServicesAdded)
        {
            return true;
        }

        new EntityFrameworkServicesBuilder(services).TryAddCoreServices();

        return false;
    }
}

　　　　我们先看ApplyService，在这个方法我们看到，是传入了Options，ServiceCollection，然后循环遍历Options的Extensions，调用他的ApplyService方法，传入serviceCollection，下图，我们看到默认是有这么多的实现，根据你在对DBContextOptionsBuilder提供的方法的使用，会给Options的Extensions添加不同的Extension，最后调用各自的ApplyService，我们找一个看看具体在做什么事情。哈哈，不用猜，大家也知道，肯定是注入服务，通过options的Extensions附加一些其他关于EF的功能，并且将他们所需要的服务注入到传入的ServiceCollection里面，其他的都是一样，所以在我们没有托管ef的ioc到web的时候可以使用这种方式来实现，后面也会写一个这样的例子。最后调用一下TryAddCoreService方法，这个方法有许多EF需用到重要的服务的注入。

　　　　而ReplaceService就是我们在调用DbContextOptionsBuilder的ReplaceService<>方法的时候里面保存的我们要替换的类型，以及实现，在这里重新注入到容器里，用上面的代码结合看，就是ApplyService先注入一遍，然后在替换一下，最后调用一下BuildServiceProvider方法生成一个ServiceProvider，在后面的代码就是一些日志相关的配置，此处就不过多讲解。

    public virtual void ApplyServices(IServiceCollection services)
        => services.AddEntityFrameworkProxies();

　　　　在上面的讲解中，我们有几个可以自定义的点就是一个是IDbContextOptionsExtension，这个我们可以在不托管ef的ioc到web的ioc的时候，我们可以实现一个这个接口，然后在代码添加到Extension就可以注入EF所需要用到的服务。接下来在下面段落，我会写一个简单的例子来注入我们要的服务。（不托管ioc到web的方式）。

EFCore服务注入

　　　　先上代码，代码没有多少，就是实现这个接口，定义一个Inject特性，用来标记从Web的IOC我们需要检索那些接口注入到EF的ioc中去，这样做有一个弊端就是Web的会注入一遍，Ef也会注入一遍，重复注入，在Program.cs里面我们先注入一个返回IServiceCollection的Func，这样在DBContext可以获取到这个 传到ServiceExtension里面，就可以拿到Web的IOC注入的服务。

    builder.Services.AddScoped<IWebGetName, WebGetName>();
    builder.Services.AddSingleton(() => builder.Services);

  [InjectAttribute]
  public interface IWebGetName
  {
      public string GetName();
  }

 [AttributeUsage(AttributeTargets.Interface| AttributeTargets.Class)]
 public class InjectAttribute:Attribute
 {
     public InjectAttribute()
     {

     }
 }

public class ServiceExtension : IDbContextOptionsExtension
{
    public ServiceExtension(Func<IServiceCollection> func)
    {
        Func = func;
    }
    public DbContextOptionsExtensionInfo Info => new ExtensionInfo(this);

    public Func<IServiceCollection> Func { get; }

    public void ApplyServices(IServiceCollection services)
    {
        var ser=Func();
        var type = ser.Where(s => s.ServiceType?.GetCustomAttribute<InjectAttribute>() != null || s.ImplementationType?.GetCustomAttribute<InjectAttribute>() != null).ToList();
        foreach (var item in type)
        {
            services.TryAdd(new ServiceDescriptor(item.ServiceType, item.ImplementationType, item.Lifetime));
        }
        services.AddScoped<IDBGetName, DBGetName>();
    }

    public void Validate(IDbContextOptions options)
    {
    }
}
 public class ExtensionInfo: DbContextOptionsExtensionInfo
 {
     public ExtensionInfo(IDbContextOptionsExtension extension):base(extension)
     {

     }
     public override bool IsDatabaseProvider => false;

     public override string LogFragment => string.Empty;

     public override int GetServiceProviderHashCode()
     {
         return 0;
     }

     public override void PopulateDebugInfo(IDictionary<string, string> debugInfo)
     {
     }

     public override bool ShouldUseSameServiceProvider(DbContextOptionsExtensionInfo other)
     {
         return true;
     }
 }

　　　　接口定义好之后，服务也注入进去，接下来就是在DBContext里面添加这个扩展,因为optionsBuilder.Options只读，所以我们添加Extension就需要用AddOrUpdateExtension的方法来添加，因为Options在DbContextOptionsBuilder的内部字段是可以更改的。接下来扩展添加进去之后，我们运行程序，获取一个DBContext，然后就会走到这里添加我们的扩展，从而注入我们注入的IWebGetName，就可以在EF的IOC获取我们web注入服务。

  builder.Services.AddDbContext<DecodeMicroMsgContext>((a, m) => {

      ((IDbContextOptionsBuilderInfrastructure)m).AddOrUpdateExtension(new ServiceExtension(a.GetService<Func<IServiceCollection>>()));
      m.UseSqlite("Data Source=C:\\Users\\Chenxd\\Desktop\\资料\\CrackMsg\\CrackDb\\CrackDb\\bin\\Debug\\net7.0-windows\\TOOLS\\output\\decode_MicroMsg.db;");
  });

拦截查询

　　Sql拦截

　　　　针对SQL拦截，这里我会直接贴上我之前有一篇文章aop的代码，来作为讲解，其中有用到了DBInterceptor作为拦截器拦截DBCommand进行sql拦截，实现读写分离的方式，下面的代码是我自己实现了DBCommandInterceptor来实现的一个拦截器，在DBContext中将拦截器添加进去，在每次执行查询或者增加删除修改的时候，都会进入这个拦截器，从而实现自己想要的业务逻辑，我在此处是写了一个简单的读写分离，感兴趣的可以看看之前的文章https://www.cnblogs.com/1996-Chinese-Chen/p/15776120.html这个文章的代码地址已经失效，最后我会将本例程的所有代码放在百度网盘，其中包括这个AOP的代码，感兴趣的朋友可以下载看看。

    var list=new List<IInterceptor>();
    list.Add(new DbContextInterceptor());
    optionsBuilder.AddInterceptors(list);

    public class DbContextInterceptor:DbCommandInterceptor
    {
        private  DbConnection _connection;
        private  DbCommand _command;
        private CommandSource _commandSource;
        public DbContextInterceptor()
        {

        }
        public override DbCommand CommandCreated(CommandEndEventData eventData, DbCommand result)
        {
            return _command;
        }
        public override InterceptionResult<DbCommand> CommandCreating(CommandCorrelatedEventData eventData, InterceptionResult<DbCommand> result)
        {
            _commandSource = eventData.CommandSource;
            if (eventData.CommandSource==CommandSource.LinqQuery)
            {
                _connection = new MySqlConnection(eventData.Connection.ConnectionString);
                _command = new MySqlCommand();
            }
            return InterceptionResult<DbCommand>.SuppressWithResult(_command);
        }
        public override void CommandFailed(DbCommand command, CommandErrorEventData eventData)
        {
            base.CommandFailed(command, eventData);
        }
        public override Task CommandFailedAsync(DbCommand command, CommandErrorEventData eventData, CancellationToken cancellationToken = default)
        {
            return base.CommandFailedAsync(command, eventData, cancellationToken);
        }
        public override InterceptionResult DataReaderDisposing(DbCommand command, DataReaderDisposingEventData eventData, InterceptionResult result)
        {
            return base.DataReaderDisposing(command, eventData, result);
        }
        public override int NonQueryExecuted(DbCommand command, CommandExecutedEventData eventData, int result)
        {
            return base.NonQueryExecuted(command, eventData, result);
        }
        public override ValueTask<int> NonQueryExecutedAsync(DbCommand command, CommandExecutedEventData eventData, int result, CancellationToken cancellationToken = default)
        {
            return base.NonQueryExecutedAsync(command, eventData, result, cancellationToken);
        }
        public override InterceptionResult<int> NonQueryExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<int> result)
        {
            return base.NonQueryExecuting(command, eventData, result);
        }
        public override ValueTask<InterceptionResult<int>> NonQueryExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<int> result, CancellationToken cancellationToken = default)
        {
            return base.NonQueryExecutingAsync(command, eventData, result, cancellationToken);
        }
        public override DbDataReader ReaderExecuted(DbCommand command, CommandExecutedEventData eventData, DbDataReader result)
        {
            return base.ReaderExecuted(command, eventData, result);
        }
        public override ValueTask<DbDataReader> ReaderExecutedAsync(DbCommand command, CommandExecutedEventData eventData, DbDataReader result, CancellationToken cancellationToken = default)
        {
            return base.ReaderExecutedAsync(command, eventData, result, cancellationToken);
        }
        public override InterceptionResult<DbDataReader> ReaderExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result)
        {
            command.CommandText = "";
            return base.ReaderExecuting(command, eventData, result);
        }
        public async override ValueTask<InterceptionResult<DbDataReader>> ReaderExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result, CancellationToken cancellationToken = default)
        {
            InterceptionResult<DbDataReader> results;
            if (_commandSource == CommandSource.LinqQuery)
            {
                var connect = new MySqlConnection("data source=192.168.21.129;database=MasterSlave; userid=root;pwd=199645; charset=utf8;ConvertZeroDateTime=True;pooling=true; allowuservariables=true;");
                connect.Open();
                _command = new MySqlCommand(command.CommandText, connect);
                var reader = await _command.ExecuteReaderAsync();
                results = InterceptionResult<DbDataReader>.SuppressWithResult(reader);
            }
            else
            {
                results=await base.ReaderExecutingAsync(command, eventData, result, cancellationToken);
            }
            return results;
        }
        public override object ScalarExecuted(DbCommand command, CommandExecutedEventData eventData, object result)
        {
            return base.ScalarExecuted(command, eventData, result);
        }
        public override ValueTask<object> ScalarExecutedAsync(DbCommand command, CommandExecutedEventData eventData, object result, CancellationToken cancellationToken = default)
        {
            return base.ScalarExecutedAsync(command, eventData, result, cancellationToken);
        }
        public override InterceptionResult<object> ScalarExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<object> result)
        {
            return base.ScalarExecuting(command, eventData, result);
        }
        public override ValueTask<InterceptionResult<object>> ScalarExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<object> result, CancellationToken cancellationToken = default)
        {
            return base.ScalarExecutingAsync(command, eventData, result, cancellationToken);
        }
    }

　　表达式拦截

　　　　上面我们讲了SQL拦截，接下来我们讲一下表达式拦截，我们都知道，EF的核心在于表达式树，可以说表达式树构造了整个EF的核心，关于表达式树，我在我的第一篇博客就写了很多关于表达式树的案例，https://www.cnblogs.com/1996-Chinese-Chen/p/14987967.html，感兴趣的朋友可以看看，所以此处表达式树我不会做讲解，只有如何实现自定义的表达式树拦截，

　　　　重要的有三个我们需要实现的接口，一个是IQueryable，IQueryCompiler，还有一个IAsyncQueryProvider，通过实现这三个接口，外加IDatabase，IQueryContextFactory需要用到的两个接口，实际上只是表达式拦截，只需要实现一个IQueryCompiler也可以实现，我i自己是实现了这三个，最主要的还是在IQueryCompiler，接下来看看具体的实现代码。

　　　　IQueryCompiler

public class TestQueryCompiler : IQueryCompiler
    {
        public TestQueryCompiler(IDatabase database, IQueryContextFactory queryContextFactory)
        {
            Database = database;
            var a = Database.GetType();
            QueryContextFactory = queryContextFactory;
        }

        public IDatabase Database { get; }
        public IQueryContextFactory QueryContextFactory { get; }

        public Func<QueryContext, TResult> CreateCompiledAsyncQuery<TResult>(Expression query)
        {
            var queryFunc = Database.CompileQuery<TResult>(query, true);
            return queryFunc;
        }

        public Func<QueryContext, TResult> CreateCompiledQuery<TResult>(Expression query)
        {
            var queryFunc = Database.CompileQuery<TResult>(query, false);
            return queryFunc;
        }

        public TResult Execute<TResult>(Expression query)
        {
            var queryFunc = Database.CompileQuery<TResult>(query, false);
            var res = queryFunc(QueryContextFactory.Create());
            return res;
        }

        public TResult ExecuteAsync<TResult>(Expression query, CancellationToken cancellationToken)
        {
            var queryFunc = Database.CompileQuery<TResult>(query, true);
            var res = queryFunc(QueryContextFactory.Create());
            return res;
        }
    }

　　　　IAsyncQueryProvider

　　　　

 public class TestQueryProvider : IAsyncQueryProvider
 {
     public TestQueryProvider(IDBGetName ta, IQueryCompiler query,IWebGetName webGetName)
     {
         Ta = ta;
         Query = query;
         WebGetName = webGetName;
     }

     public IDBGetName Ta { get; }
     public IQueryCompiler Query { get; }
     public IWebGetName WebGetName { get; }

     public IQueryable CreateQuery(Expression expression)
     {
         return new Queryable<object>(this, expression);
     }

     public IQueryable<TElement> CreateQuery<TElement>(Expression expression)
     {
         return new Queryable<TElement>(this, expression);
     }

     public object? Execute(Expression expression)
     {
         return Query.Execute<object>(expression);
     }

     public TResult Execute<TResult>(Expression expression)
     {
         return Query.Execute<TResult>(expression);
     }

     public TResult ExecuteAsync<TResult>(Expression expression, CancellationToken cancellationToken = default)
     {
         return Query.ExecuteAsync<TResult>(expression, cancellationToken);
     }
 }　　

　　　　IQueryable

 public class Queryable<T> : IQueryable<T>
 {
     public Queryable(IAsyncQueryProvider queryProvider, Expression expression)
     {
         QueryProvider = queryProvider;
         Expression = expression;
     }
     public Type ElementType => typeof(T);

     public IAsyncQueryProvider QueryProvider { get; }
     public Expression Expression { get; }

     public IQueryProvider Provider => QueryProvider;

     public IEnumerator GetEnumerator()
     {
         return Provider.Execute<IEnumerable>(Expression).GetEnumerator();
     }

     IEnumerator<T> IEnumerable<T>.GetEnumerator()
     {
         return Provider.Execute<IEnumerable<T>>(Expression).GetEnumerator();
     }
 }

　　　　在实现了那三个接口之后，我们就需要将我们的服务使用DBContextOptionsBuilder的ReplaceService替换掉，这样，在执行查询的时候就会走我们创建的TestQueryProvider，然后我们在这个类里调用关于Queryable和TestQueryCompiler来执行查询，如果又需要修改，也可以修改Expression从而达到拦截修改。我们最终是需要借助IDataBase的CompileQuery方法来实现构建查询的委托，从而实现查询，在底层还有Visitor遍历表达式树，当然了，此处我只展示一个拦截表达式树，后续的源码讲解会看到，欢迎大家关注。

　　　　如果是使用了EF的IOC托管到了Web的IOC，只需要正常注入服务就行，生命周期是Scope，

 #未接管
 optionsBuilder.ReplaceService<IAsyncQueryProvider,TestQueryProvider >();
 optionsBuilder.ReplaceService<IQueryCompiler,TestQueryCompiler>();
#接管IOC

builder.Services.AddScoped<IAsyncQueryProvider, TestQueryProvider>();
   builder.Services.AddScoped<IQueryCompiler, TestQueryCompiler>(s =>
   {
   var database = s.GetService<IDatabase>();
   var factory = s.GetService<IQueryContextFactory>();
   return new TestQueryCompiler(database, factory);
   });

缓存查询方法

　　　　在上面的代码中，我们可以看到我们调用了一个ComileQuery方法，构建了一个委托，实际上，我们在业务编码中，也可以使用缓存查询，来提升业务系统的性能，虽然我们不能使用IDataBase的这个发给发，但是EF提供了一个静态类，里面的ComileQuery方法支持构建查询的委托，

　　　　看下面代码，我们可以调用这个方法缓存一个查询的方法，后面就不会再去调用很多的类，很多的方法来实现我们的查询，可以缓存起来，来提升我们的查询性能，同时这个ComileQuery方法最终也会调用到我们上面自定义的TestQueryCompiler的ComileQuery方法去，并且同步对同步，异步对异步.

  public class WeatherForecastController : ControllerBase
  {
      private static readonly string[] Summaries = new[]
      {
      "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
  };
      private Func<DecodeMicroMsgContext, IQueryable<Contact>> Func;
      private readonly ILogger<WeatherForecastController> _logger;
      private readonly IWebGetName webGetName;

      public WeatherForecastController(ILogger<WeatherForecastController> logger,IWebGetName webGetName, DecodeMicroMsgContext dbContext)
      {
          _logger = logger;
          this.webGetName = webGetName;
          DbContext = dbContext;
      }

      public DecodeMicroMsgContext DbContext { get; }

      [HttpGet(Name = "GetWeatherForecast")]
      public List<Contact> Get()
      {
          Func = EF.CompileQuery<DecodeMicroMsgContext, IQueryable<Contact>>(s => s.Contacts.Take(10));
          return DbContext.Contacts.Take(10).ToList();
      }

EF的IOC托管到WEB的IOC

　　　　在上面讲源码的时候，我们提到了一个方法，叫UseInternalServiceProvider，我们需要借助这个方法来把EF的ioc托管到web，同样是DBContextOptionsBuilder的方法，将web的ServiceProvider获取到并且调用这个方法，同时，我们还需要在Program.cs调用一个方法  builder.Services.AddEntityFrameworkSqlite();如果是其他数据库也是一样的道理，需要调用这样的方法，可以看第三方提供的库源码，或者文档，这里我是SQLITE数据库，就调用这个方法，这个方法是将SqlLite的一些服务注入到容器里，并且将我们的web容器传入到EF里面去，这样EF注入的服务是和Web注入的服务是在一起的，然后在调用UseInternalServiceProvider指定ServiceProvider就可以实现EF和WEB共用一个IOC。

　　　　下面是Program的Main方法的所有代码。

 public static void Main(string[] args)
 {
     var builder = WebApplication.CreateBuilder(args);
     builder.Services.AddScoped<IWebGetName,WebGetName>();
     builder.Services.AddScoped<IAsyncQueryProvider, TestQueryProvider>();
     builder.Services.AddScoped<IQueryCompiler, TestQueryCompiler>(s =>
     {
         var database = s.GetService<IDatabase>();
         var factory = s.GetService<IQueryContextFactory>();
         return new TestQueryCompiler(database, factory);
     });
     builder.Services.AddScoped<IDBGetName, DBGetName>();
     builder.Services.AddEntityFrameworkSqlite();
     builder.Services.AddDbContext<DecodeMicroMsgContext>((a, m) => {
         m.UseSqlite("Data Source=C:\\Users\\Chenxd\\Desktop\\资料\\CrackMsg\\CrackDb\\CrackDb\\bin\\Debug\\net7.0-windows\\TOOLS\\output\\decode_MicroMsg.db;");
     });
     builder.Services.AddControllers();
     // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
     builder.Services.AddEndpointsApiExplorer();
     builder.Services.AddSwaggerGen();
     builder.Services.AddSingleton(() => builder.Services);
     var app = builder.Build();

     // Configure the HTTP request pipeline.
     if (app.Environment.IsDevelopment())
     {
         app.UseSwagger();
         app.UseSwaggerUI();
     }

     app.UseAuthorization();

     app.MapControllers();

     app.Run();
 }

    public static IServiceCollection AddEntityFrameworkSqlite(this IServiceCollection serviceCollection)
    {
        var builder = new EntityFrameworkRelationalServicesBuilder(serviceCollection)
            .TryAdd<LoggingDefinitions, SqliteLoggingDefinitions>()
            .TryAdd<IDatabaseProvider, DatabaseProvider<SqliteOptionsExtension>>()
            .TryAdd<IRelationalTypeMappingSource, SqliteTypeMappingSource>()
            .TryAdd<ISqlGenerationHelper, SqliteSqlGenerationHelper>()
            .TryAdd<IRelationalAnnotationProvider, SqliteAnnotationProvider>()
            .TryAdd<IModelValidator, SqliteModelValidator>()
            .TryAdd<IProviderConventionSetBuilder, SqliteConventionSetBuilder>()
            .TryAdd<IModificationCommandBatchFactory, SqliteModificationCommandBatchFactory>()
            .TryAdd<IRelationalConnection>(p => p.GetRequiredService<ISqliteRelationalConnection>())
            .TryAdd<IMigrationsSqlGenerator, SqliteMigrationsSqlGenerator>()
            .TryAdd<IRelationalDatabaseCreator, SqliteDatabaseCreator>()
            .TryAdd<IHistoryRepository, SqliteHistoryRepository>()
            .TryAdd<IRelationalQueryStringFactory, SqliteQueryStringFactory>()
            .TryAdd<IMethodCallTranslatorProvider, SqliteMethodCallTranslatorProvider>()
            .TryAdd<IAggregateMethodCallTranslatorProvider, SqliteAggregateMethodCallTranslatorProvider>()
            .TryAdd<IMemberTranslatorProvider, SqliteMemberTranslatorProvider>()
            .TryAdd<IQuerySqlGeneratorFactory, SqliteQuerySqlGeneratorFactory>()
            .TryAdd<IQueryableMethodTranslatingExpressionVisitorFactory, SqliteQueryableMethodTranslatingExpressionVisitorFactory>()
            .TryAdd<IRelationalSqlTranslatingExpressionVisitorFactory, SqliteSqlTranslatingExpressionVisitorFactory>()
            .TryAdd<IQueryTranslationPostprocessorFactory, SqliteQueryTranslationPostprocessorFactory>()
            .TryAdd<IUpdateSqlGenerator>(
                sp =>
                {
                    // Support for the RETURNING clause on INSERT/UPDATE/DELETE was added in Sqlite 3.35.
                    // Detect which version we're using, and fall back to the older INSERT/UPDATE+SELECT behavior on legacy versions.
                    var dependencies = sp.GetRequiredService<UpdateSqlGeneratorDependencies>();

                    return new Version(new SqliteConnection().ServerVersion) < new Version(3, 35)
                        ? new SqliteLegacyUpdateSqlGenerator(dependencies)
                        : new SqliteUpdateSqlGenerator(dependencies);
                })
            .TryAdd<ISqlExpressionFactory, SqliteSqlExpressionFactory>()
            .TryAddProviderSpecificServices(
                b => b.TryAddScoped<ISqliteRelationalConnection, SqliteRelationalConnection>());

        builder.TryAddCoreServices();

        return serviceCollection;
    }

using EfDemo.Models;
using Microsoft.EntityFrameworkCore.Infrastructure;
using Microsoft.EntityFrameworkCore.Query.Internal;
using Microsoft.EntityFrameworkCore.Query;
using Microsoft.EntityFrameworkCore;
using EfDemo.QueryableExtension;
using EfDemo.DBExtension;
using Microsoft.EntityFrameworkCore.Diagnostics;

namespace EfDemo.DB
{

    public partial class DecodeMicroMsgContext : DbContext
    {
        public DecodeMicroMsgContext(Func<IServiceCollection> func, IServiceProvider serviceProvider)
        {
            Func = func;
            ServiceProvider = serviceProvider;
        }

        public DecodeMicroMsgContext(DbContextOptions<DecodeMicroMsgContext> options, Func<IServiceCollection> func,IServiceProvider serviceProvider)
            : base(options)
        {

            Func = func;
            ServiceProvider = serviceProvider;
        }

        public virtual DbSet<AppInfo> AppInfos { get; set; }

        public virtual DbSet<BizInfo> BizInfos { get; set; }

        public virtual DbSet<BizName2Id> BizName2Ids { get; set; }

        public virtual DbSet<BizProfileInfo> BizProfileInfos { get; set; }

        public virtual DbSet<BizProfileV2> BizProfileV2s { get; set; }

        public virtual DbSet<BizSessionNewFeed> BizSessionNewFeeds { get; set; }

        public virtual DbSet<ChatInfo> ChatInfos { get; set; }

        public virtual DbSet<ChatLiveInfo> ChatLiveInfos { get; set; }

        public virtual DbSet<ChatRoom> ChatRooms { get; set; }

        public virtual DbSet<ChatRoomInfo> ChatRoomInfos { get; set; }

        public virtual DbSet<ChatroomTool> ChatroomTools { get; set; }

        public virtual DbSet<Contact> Contacts { get; set; }

        public virtual DbSet<ContactHeadImgUrl> ContactHeadImgUrls { get; set; }

        public virtual DbSet<ContactLabel> ContactLabels { get; set; }

        public virtual DbSet<DelayDownLoad> DelayDownLoads { get; set; }

        public virtual DbSet<FtschatroomTran> FtschatroomTrans { get; set; }

        public virtual DbSet<FtscontactTran> FtscontactTrans { get; set; }

        public virtual DbSet<MainConfig> MainConfigs { get; set; }

        public virtual DbSet<OpLog> OpLogs { get; set; }

        public virtual DbSet<PatInfo> PatInfos { get; set; }

        public virtual DbSet<RevokeMsgStorage> RevokeMsgStorages { get; set; }

        public virtual DbSet<Session> Sessions { get; set; }

        public virtual DbSet<TicketInfo> TicketInfos { get; set; }

        public virtual DbSet<TopStoryReddotInfo> TopStoryReddotInfos { get; set; }
        public IServiceProvider ServiceProvider { get; }
        public IServiceCollection ServiceDescriptors { get; }
        public Func<IServiceCollection> Func { get; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseInternalServiceProvider(ServiceProvider);
           // optionsBuilder.ReplaceService<IAsyncQueryProvider, TestQueryProvider>();
           // optionsBuilder.ReplaceService<IQueryCompiler, TestQueryCompiler>();
            // ((IDbContextOptionsBuilderInfrastructure)s).AddOrUpdateExtension(new Extension());
            //var interceptor = new List<IInterceptor>();
            //optionsBuilder.AddInterceptors();
            ((IDbContextOptionsBuilderInfrastructure)optionsBuilder).AddOrUpdateExtension(new ServiceExtension(Func));
            base.OnConfiguring(optionsBuilder);
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<AppInfo>(entity =>
            {
                entity.HasKey(e => e.InfoKey);

                entity.ToTable("AppInfo");

                entity.Property(e => e.Description4EnUs).HasColumnName("Description4EnUS");
                entity.Property(e => e.Description4ZhTw).HasColumnName("Description4ZhTW");
                entity.Property(e => e.Name4EnUs).HasColumnName("Name4EnUS");
                entity.Property(e => e.Name4ZhTw).HasColumnName("Name4ZhTW");
                entity.Property(e => e.Version).HasColumnType("INT");
            });

            modelBuilder.Entity<BizInfo>(entity =>
            {
                entity.HasKey(e => e.UserName);

                entity.ToTable("BizInfo");

                entity.Property(e => e.AcceptType).HasDefaultValueSql("0");
                entity.Property(e => e.BrandFlag).HasDefaultValueSql("0");
                entity.Property(e => e.BrandIconUrl).HasColumnName("BrandIconURL");
                entity.Property(e => e.Reserved1).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved3).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved5).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved7).HasDefaultValueSql("0");
                entity.Property(e => e.Type).HasDefaultValueSql("0");
                entity.Property(e => e.UpdateTime).HasDefaultValueSql("0");
            });

            modelBuilder.Entity<BizName2Id>(entity =>
            {
                entity.HasKey(e => e.UsrName);

                entity.ToTable("BizName2ID");
            });

            modelBuilder.Entity<BizProfileInfo>(entity =>
            {
                entity.HasKey(e => e.TableIndex);

                entity.ToTable("BizProfileInfo");

                entity.HasIndex(e => e.TableIndex, "versionIdx");

                entity.Property(e => e.TableIndex)
                    .ValueGeneratedNever()
                    .HasColumnName("tableIndex");
                entity.Property(e => e.TableDesc).HasColumnName("tableDesc");
                entity.Property(e => e.TableVersion)
                    .HasColumnType("INTERGER")
                    .HasColumnName("tableVersion");
            });

            modelBuilder.Entity<BizProfileV2>(entity =>
            {
                entity.HasKey(e => e.TalkerId);

                entity.ToTable("BizProfileV2");

                entity.HasIndex(e => e.TimeStamp, "BizProfileV2TimeIdx");

                entity.Property(e => e.TalkerId).ValueGeneratedNever();
            });

            modelBuilder.Entity<BizSessionNewFeed>(entity =>
            {
                entity.HasKey(e => e.TalkerId);

                entity.HasIndex(e => e.CreateTime, "BizSessionNewFeedsCreateTimeIdx");

                entity.HasIndex(e => e.UpdateTime, "BizSessionNewFeedsUpdateTimeIdx");

                entity.Property(e => e.TalkerId).ValueGeneratedNever();
            });

            modelBuilder.Entity<ChatInfo>(entity =>
            {
                entity
                    .HasNoKey()
                    .ToTable("ChatInfo");

                entity.HasIndex(e => e.Username, "ChatInfoUserNameIndex");
            });

            modelBuilder.Entity<ChatLiveInfo>(entity =>
            {
                entity
                    .HasNoKey()
                    .ToTable("ChatLiveInfo");

                entity.HasIndex(e => new { e.RoomName, e.LiveId }, "IX_ChatLiveInfo_RoomName_LiveId").IsUnique();

                entity.HasIndex(e => e.LiveId, "ChatLiveInfoLiveIdIdx");

                entity.HasIndex(e => e.RoomName, "ChatLiveInfoRoomNamex");
            });

            modelBuilder.Entity<ChatRoom>(entity =>
            {
                entity.HasKey(e => e.ChatRoomName);

                entity.ToTable("ChatRoom");

                entity.Property(e => e.ChatRoomFlag)
                    .HasDefaultValueSql("0")
                    .HasColumnType("INT");
                entity.Property(e => e.IsShowName).HasDefaultValueSql("0");
                entity.Property(e => e.Owner).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved1).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved3).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved5).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved7).HasDefaultValueSql("0");
            });

            modelBuilder.Entity<ChatRoomInfo>(entity =>
            {
                entity.HasKey(e => e.ChatRoomName);

                entity.ToTable("ChatRoomInfo");

                entity.Property(e => e.AnnouncementPublishTime).HasDefaultValueSql("0");
                entity.Property(e => e.ChatRoomStatus).HasDefaultValueSql("0");
                entity.Property(e => e.InfoVersion).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved1).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved3).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved5).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved7).HasDefaultValueSql("0");
            });

            modelBuilder.Entity<ChatroomTool>(entity =>
            {
                entity
                    .HasNoKey()
                    .ToTable("ChatroomTool");

                entity.HasIndex(e => e.ChatroomUsername, "IX_ChatroomTool_ChatroomUsername").IsUnique();
            });

            modelBuilder.Entity<Contact>(entity =>
            {
                entity.HasKey(e => e.UserName);

                entity.ToTable("Contact");

                entity.HasIndex(e => e.Reserved2, "Contact_Idx0");

                entity.Property(e => e.ChatRoomNotify).HasDefaultValueSql("0");
                entity.Property(e => e.ChatRoomType).HasColumnType("INT");
                entity.Property(e => e.DelFlag).HasDefaultValueSql("0");
                entity.Property(e => e.LabelIdlist).HasColumnName("LabelIDList");
                entity.Property(e => e.Pyinitial).HasColumnName("PYInitial");
                entity.Property(e => e.RemarkPyinitial).HasColumnName("RemarkPYInitial");
                entity.Property(e => e.Reserved1).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved2).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved5).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved8).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved9).HasDefaultValueSql("0");
                entity.Property(e => e.Type).HasDefaultValueSql("0");
                entity.Property(e => e.VerifyFlag).HasDefaultValueSql("0");
            });

            modelBuilder.Entity<ContactHeadImgUrl>(entity =>
            {
                entity.HasKey(e => e.UsrName);

                entity.ToTable("ContactHeadImgUrl");

                entity.HasIndex(e => e.Reverse0, "reverse0Index");

                entity.Property(e => e.UsrName).HasColumnName("usrName");
                entity.Property(e => e.BigHeadImgUrl).HasColumnName("bigHeadImgUrl");
                entity.Property(e => e.HeadImgMd5).HasColumnName("headImgMd5");
                entity.Property(e => e.Reverse0)
                    .HasColumnType("INT")
                    .HasColumnName("reverse0");
                entity.Property(e => e.Reverse1).HasColumnName("reverse1");
                entity.Property(e => e.SmallHeadImgUrl).HasColumnName("smallHeadImgUrl");
            });

            modelBuilder.Entity<ContactLabel>(entity =>
            {
                entity.HasKey(e => e.LabelId);

                entity.ToTable("ContactLabel");

                entity.Property(e => e.LabelId).ValueGeneratedNever();
            });

            modelBuilder.Entity<DelayDownLoad>(entity =>
            {
                entity
                    .HasNoKey()
                    .ToTable("DelayDownLoad");

                entity.HasIndex(e => e.MessageServId, "IX_DelayDownLoad_MessageServId").IsUnique();
            });

            modelBuilder.Entity<FtschatroomTran>(entity =>
            {
                entity
                    .HasNoKey()
                    .ToTable("FTSChatroomTrans");

                entity.Property(e => e.DisplayName).HasColumnName("displayName");
                entity.Property(e => e.GroupUsername).HasColumnName("groupUsername");
                entity.Property(e => e.Nickname).HasColumnName("nickname");
                entity.Property(e => e.Operation).HasColumnName("operation");
                entity.Property(e => e.Reserve1).HasColumnName("reserve1");
                entity.Property(e => e.Reserve2).HasColumnName("reserve2");
                entity.Property(e => e.Username).HasColumnName("username");
            });

            modelBuilder.Entity<FtscontactTran>(entity =>
            {
                entity
                    .HasNoKey()
                    .ToTable("FTSContactTrans");

                entity.Property(e => e.Reserve1).HasColumnName("reserve1");
                entity.Property(e => e.Reserve2).HasColumnName("reserve2");
                entity.Property(e => e.Username).HasColumnName("username");
            });

            modelBuilder.Entity<MainConfig>(entity =>
            {
                entity.HasKey(e => e.Key);

                entity.ToTable("MainConfig");

                entity.HasIndex(e => e.Reserved0, "MainConfigReserved0Idx");

                entity.HasIndex(e => e.Reserved1, "MainConfigReserved1Idx");

                entity.Property(e => e.Reserved0).HasColumnType("INT");
                entity.Property(e => e.Reserved1).HasColumnType("INT");
            });

            modelBuilder.Entity<OpLog>(entity =>
            {
                entity.ToTable("OpLog");

                entity.Property(e => e.Id)
                    .ValueGeneratedNever()
                    .HasColumnName("ID");
                entity.Property(e => e.CmditemBuffer).HasColumnName("CMDItemBuffer");
            });

            modelBuilder.Entity<PatInfo>(entity =>
            {
                entity.HasKey(e => e.Username);

                entity.ToTable("PatInfo");

                entity.Property(e => e.Username).HasColumnName("username");
                entity.Property(e => e.Reserved1)
                    .HasDefaultValueSql("0")
                    .HasColumnName("reserved1");
                entity.Property(e => e.Reserved2)
                    .HasDefaultValueSql("0")
                    .HasColumnName("reserved2");
                entity.Property(e => e.Reserved3)
                    .HasDefaultValueSql("0")
                    .HasColumnName("reserved3");
                entity.Property(e => e.Reserved4)
                    .HasDefaultValueSql("0")
                    .HasColumnName("reserved4");
                entity.Property(e => e.Reserved5).HasColumnName("reserved5");
                entity.Property(e => e.Reserved6).HasColumnName("reserved6");
                entity.Property(e => e.Reserved7).HasColumnName("reserved7");
                entity.Property(e => e.Reserved8).HasColumnName("reserved8");
                entity.Property(e => e.Reserved9).HasColumnName("reserved9");
                entity.Property(e => e.Suffix).HasColumnName("suffix");
            });

            modelBuilder.Entity<RevokeMsgStorage>(entity =>
            {
                entity.HasKey(e => e.CreateTime);

                entity.ToTable("RevokeMsgStorage");

                entity.HasIndex(e => e.MsgSvrId, "MsgSvrId_Idx");

                entity.HasIndex(e => e.RevokeSvrId, "RevokeSvrID_Idx");

                entity.Property(e => e.CreateTime).ValueGeneratedNever();
                entity.Property(e => e.MsgSvrId)
                    .HasColumnType("INTERGER")
                    .HasColumnName("MsgSvrID");
                entity.Property(e => e.RevokeSvrId)
                    .HasColumnType("INTERGER")
                    .HasColumnName("RevokeSvrID");
            });

            modelBuilder.Entity<Session>(entity =>
            {
                entity.HasKey(e => e.StrUsrName);

                entity.ToTable("Session");

                entity.HasIndex(e => e.NOrder, "nOrderIndex");

                entity.Property(e => e.StrUsrName).HasColumnName("strUsrName");
                entity.Property(e => e.BytesXml).HasColumnName("bytesXml");
                entity.Property(e => e.EditContent).HasColumnName("editContent");
                entity.Property(e => e.NIsSend).HasColumnName("nIsSend");
                entity.Property(e => e.NMsgLocalId).HasColumnName("nMsgLocalID");
                entity.Property(e => e.NMsgStatus).HasColumnName("nMsgStatus");
                entity.Property(e => e.NMsgType).HasColumnName("nMsgType");
                entity.Property(e => e.NOrder)
                    .HasDefaultValueSql("0")
                    .HasColumnType("INT")
                    .HasColumnName("nOrder");
                entity.Property(e => e.NStatus).HasColumnName("nStatus");
                entity.Property(e => e.NTime).HasColumnName("nTime");
                entity.Property(e => e.NUnReadCount)
                    .HasDefaultValueSql("0")
                    .HasColumnName("nUnReadCount");
                entity.Property(e => e.OthersAtMe)
                    .HasColumnType("INT")
                    .HasColumnName("othersAtMe");
                entity.Property(e => e.ParentRef).HasColumnName("parentRef");
                entity.Property(e => e.Reserved0).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved2).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved4).HasDefaultValueSql("0");
                entity.Property(e => e.StrContent).HasColumnName("strContent");
                entity.Property(e => e.StrNickName).HasColumnName("strNickName");
            });

            modelBuilder.Entity<TicketInfo>(entity =>
            {
                entity.HasKey(e => e.UserName);

                entity.ToTable("TicketInfo");

                entity.Property(e => e.Reserved1).HasDefaultValueSql("0");
                entity.Property(e => e.Reserved3).HasDefaultValueSql("0");
            });

            modelBuilder.Entity<TopStoryReddotInfo>(entity =>
            {
                entity.HasKey(e => e.MsgId);

                entity.ToTable("TopStoryReddotInfo");

                entity.Property(e => e.H5version).HasColumnName("H5Version");
            });

            OnModelCreatingPartial(modelBuilder);
        }

        partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
    }
}

结尾

　　　　在本文中，我们一共讲了AddDbContext做了什么，DBContext的构造函数又做了那些事情，在写了不托管EF的ioc到WEB的ioc的场景下如果注入服务到EF的ioc中，以及如何拦截增删改查的方式，提升查询性能的方式，以及最后的EF的ioc托管到WEB的ioc，本文作为源码讲解的第一章，觉得写的有点多，如果又看不懂的地方，或者代码下载下来没办法运行或者保存的地方可以随时联系我，QQ934550201.我们下次再见。数据库是我破解的我本地的微信数据的一部分，emmm作为了本次的例子，我希望大家能够合理看待我的这个数据库的数据，不要做一些不好的事情，谢谢大家。

　　　　本次的代码例子地址

链接：https://pan.baidu.com/s/1w6kFG5MCJYE0jzEBxjQTKw

提取码：foin

　　　　之前AOP的代码例子

　　　　链接：https://pan.baidu.com/s/1AJe4-KhjIESbDtFNqM968Q
　　　　提取码：jp20