Question

您好我已经将我的UnitOfWork创建为通用的，并且在运行时它应该在TContext传递的基础上使用DBContextOption Builder创建新的DB上下文实例我已经在autofac中注册了Mention DB Context但是如何在DB Context Constructor Level < / p>

数据库上下文1实现

public class DBContext1 : DbContext
{
    public DBContext1(DbContextOptions<DBContext1> options1) : base(options1)
    {

    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
    }
}

数据库上下文2实现

public class DBContext2 : DbContext
{
    public DBContext2(DbContextOptions<DBContext2> options2) : base(options2)
    {

    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
    }
}

IUnitOfWork接口实现

public interface IUnitOfWork<TContext> where TContext : DbContext, IDisposable
{

}

UnitOfWork类实现

public class UnitOfWork<TContext> : IDisposable, IUnitOfWork<TContext> where TContext : DbContext, new()
{
    private DbContext _context;
    public UnitOfWork()
    {
        _context = new TContext();
    }
}

StartUp Class Implemetation

public class Startup
{
    protected IConfiguration _configuration { get; set; }

    public Startup(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    public IServiceProvider ConfigureServices(IServiceCollection services)
    {

        services.AddMvc();

        services.AddEntityFrameworkSqlServer()
            .AddDbContext<DBContext1>(options =>
            options.UseSqlServer(_configuration.GetConnectionString("DBContext1")))
            .AddDbContext<DBContext2>(options =>
            options.UseSqlServer(_configuration.GetConnectionString("DBContext2")));

        /* Autofac DI Configuration with registering DBContext/DataModule/ServiceModule to it */

        var containerBuilder = new ContainerBuilder();

        containerBuilder.RegisterInstance(_configuration).AsImplementedInterfaces().ExternallyOwned();

        var autoFacOptions1 = new DbContextOptionsBuilder<DBContext1>().UseSqlServer(_configuration.GetConnectionString("DBContext1")).Options;
        var autoFacOptions2 = new DbContextOptionsBuilder<DBContext2>().UseSqlServer(_configuration.GetConnectionString("DBContext2")).Options;


        containerBuilder.Register(c => new DBContext1(autoFacOptions1)).As<DbContext>();
        containerBuilder.Register(c => new DBContext2(autoFacOptions2)).As<DbContext>();
        containerBuilder.RegisterModule<DataModule>();
        containerBuilder.RegisterModule<ServiceModule>();

        containerBuilder.Register<String>(c => Guid.NewGuid().ToString())
           .Named<String>("correlationId")
           .InstancePerLifetimeScope();

        containerBuilder.Populate(services);
        var container = containerBuilder.Build();

        return new AutofacServiceProvider(container);

    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Account}/{action=Login}/{id?}");
        });

        app.Run(async (context) =>
        {
            await context.Response.WriteAsync("Hello World!");
        });
    }
}

我可以根据需要实现多个DBContext调用，但我必须创建默认构造函数＆amp; DB上下文中的连接字符串，如下所述

数据库上下文1实现

public class DBContext1 : DbContext
{
    public DBContext1()
    {

    }

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(@"Data Source=Server;Database=DB;User Id=UserID;Password=Password;Integrated Security=False;MultipleActiveResultSets=true;");
    }

    public DBContext1(DbContextOptions<DBContext1> options1) : base(options1)
    {

    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
    }
}

数据库上下文2实现

public class DBContext2 : DbContext
{
public DBContext2()
    {

    }

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(@"Data Source=Server;Database=DB;User Id=UserID;Password=Password;Integrated Security=False;MultipleActiveResultSets=true;");
    }

    public DBContext2(DbContextOptions<DBContext2> options2) : base(options2)
    {

    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
    }
}

请帮我调用DBContext1＆amp;的参数化构造函数。 DBContext2使用autofac依赖解析器

Answer 1

好吧，如果您正在使用autofac来解决依赖关系，那么为什么要尝试为它做好工作呢？ :)这是您的代码的主要问题。

首先，您不需要明确注册IConfiguration。它已在IServiceCollection中注册，已传递给ConfigureServices()方法，并会在containerBuilder.Populate(services)来电期间由autofac自动提取。你可以删除这个注册，什么都不会改变。

此外，您在服务集合和autofac容器构建器中重新注册了DbContext两次。这不是必要的，因为后者将有效地取代前者。此外，它会对注册的内容产生混淆，这将在何处以及如何实现这一目标。选择一种注册方法并坚持使用它会更好。

下一个问题：你如何对你的工作单元进行单元测试？它对DbContext有很强的依赖性，它的生命周期是你在测试中无法控制的。这正是您需要autofac的原因：管理组件的依赖关系，让您专注于组件的目的而不是辅助内容。

下一个混乱点在这里：

    containerBuilder.Register(c => new DBContext1(autoFacOptions1)).As<DbContext>();
    containerBuilder.Register(c => new DBContext2(autoFacOptions2)).As<DbContext>();

通过这样做，您实际上正在用第二个替换第一个db上下文注册。 ~~从这一点开始，无法在应用程序的任何位置注入DBContext1。~~ EDITED：您仍然可以注入DbContext派生实现的集合并在其中查找DBContext1。 ..但那看起来很奇怪。

总而言之，这可以通过更加干净和直接的方式完成。

<强>启动

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();

        var builder = new ContainerBuilder();

        builder.Register(c => c.CreateDbContextOptionsFor<DBContext1>("DBContext1")).As<DbContextOptions<DBContext1>>().SingleInstance();
        builder.Register(c => c.CreateDbContextOptionsFor<DBContext2>("DBContext2")).As<DbContextOptions<DBContext2>>().SingleInstance();

        builder.RegisterType<DBContext1>().AsSelf().InstancePerLifetimeScope();
        builder.RegisterType<DBContext2>().AsSelf().InstancePerLifetimeScope();

        builder.RegisterType<SomeComponent>().As<ISomeComponent>().InstancePerLifetimeScope();

        builder.RegisterGeneric(typeof(UnitOfWork<>)).As(typeof(IUnitOfWork<>)).InstancePerLifetimeScope();

        builder.Populate(services);

        var container = builder.Build();
        return new AutofacServiceProvider(container);
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        ....
    }
}

CreateDbContextOptionsFor 帮助器实现。引入它是为了使Startup代码简洁易读。通过使用autofac的参数化工厂而不是new DbContextOptionsBuilder<TContext>()，可以进一步改进它，但我不确定在这种情况下是否存在点。

public static class DBExtentions
{
    public static DbContextOptions<TContext> CreateDbContextOptionsFor<TContext>(this IComponentContext ctx,
        string connectionName) where TContext : DbContext
    {
        var connectionString = ctx.Resolve<IConfiguration>().GetConnectionString(connectionName);
        return new DbContextOptionsBuilder<TContext>().UseSqlServer(connectionString).Options;
    }
}

<强>的UnitOfWork

public class UnitOfWork<TContext> : IUnitOfWork<TContext> where TContext : DbContext
{
    private TContext _context;
    public UnitOfWork(TContext context)
    {
        _context = context;
    }
}

注射和使用工作单元

public class SomeComponent : ISomeComponent
{
    private readonly IUnitOfWork<DBContext1> _uow;

    public SomeComponent(IUnitOfWork<DBContext1> uow)
    {
        _uow = uow;
    }

    public void DoSomething()
    {
        _uow.DoWhatever();
    }

....

如何使用Autofac中的通用UnitOfWork <tcontext>来解析多个DBContext调用

1 个答案: