我一直在关注NServiceBus示例，专门针对如何使用与Sql Persistence集成的实体框架（核心）DbContext，以便我可以将dbcontext状态更改与发件箱消息一起保存。这是示例：https://docs.particular.net/samples/entity-framework-core/
我已经稍微修改了工作单元代码，以支持创建aspnet核心DI范围内的DbContext。相关代码如下：
public class UnitOfWork<TDbContext>
where TDbContext : DbContext
{
private Func<SynchronizedStorageSession, IServiceProvider, TDbContext> _contextFactory;
private TDbContext _context;
private IServiceProvider _serviceProvider;
public UnitOfWork(Func<SynchronizedStorageSession, IServiceProvider, TDbContext> contextFactory, IServiceProvider serviceProvider)
{
_contextFactory = contextFactory;
_serviceProvider = serviceProvider;
}
public TDbContext GetDataContext(SynchronizedStorageSession storageSession)
{
if (_context == null)
{
_context = _contextFactory(storageSession, _serviceProvider);
}
return _context;
}
}
public class UnitOfWorkSetupBehavior<TDbContext> : Behavior<IIncomingLogicalMessageContext>
where TDbContext : DbContext
{
private readonly Func<SynchronizedStorageSession, IServiceProvider, TDbContext> _contextFactory;
private readonly IServiceScopeFactory _serviceScopeFactory;
public UnitOfWorkSetupBehavior(Func<SynchronizedStorageSession, IServiceProvider, TDbContext> contextFactory, IServiceScopeFactory serviceScopeFactory)
{
_contextFactory = contextFactory;
_serviceScopeFactory = serviceScopeFactory;
}
public override async Task Invoke(IIncomingLogicalMessageContext context, Func<Task> next)
{
using (var scope = _serviceScopeFactory.CreateScope())
{
var uow = new UnitOfWork<TDbContext>(_contextFactory, scope.ServiceProvider);
context.Extensions.Set(uow);
await next().ConfigureAwait(false);
context.Extensions.Remove<UnitOfWork<TDbContext>>();
}
}
}
public static class EndpointConfigurationExtensions
{
public static void RegisterUnitOfWork<TDbContext>(this EndpointConfiguration endpointConfiguration, IServiceScopeFactory serviceScopeFactory)
where TDbContext : DbContext
{
var pipeline = endpointConfiguration.Pipeline;
pipeline.Register(new UnitOfWorkSetupBehavior<TDbContext>((storageSession, serviceProvider) =>
{
var dbConnection = storageSession.SqlPersistenceSession().Connection;
var dbContextFactory = serviceProvider.GetService<IDbContextConnectionFactory<TDbContext>>();
var dbContext = dbContextFactory.GetDbContext(dbConnection);
//Use the same underlying ADO.NET transaction
dbContext.Database.UseTransaction(storageSession.SqlPersistenceSession().Transaction);
//Call SaveChanges before completing storage session
storageSession.SqlPersistenceSession().OnSaveChanges(x => dbContext.SaveChangesAsync());
return dbContext;
}, serviceScopeFactory), "Sets up unit of work for the message");
}
}
public static class UnitOfWorkContextExtensions
{
public static TDbContext DataContext<TDbContext>(this IMessageHandlerContext context)
where TDbContext : DbContext
{
var uow = context.Extensions.Get<UnitOfWork<TDbContext>>();
return uow.GetDataContext(context.SynchronizedStorageSession);
}
}
为此，此行为需要注入IServiceScopeFactory。
现在我能够找到行为注册的所有示例仅显示手动实例化的类型，并将其传递给端点配置的管道。
是否可以通过行为的Invoke方法（也许是通过上下文通过某种扩展名来获得对IServiceScopeFactory的访问权？或者可以注册行为本身，以便可以使用由行为创建的服务来构造它） DI容器？
仅供参考，我查看了this问答，这给了我注入IServiceScopeFactory的想法。不幸的是，答案没有显示如何实际获取接口的实例。
https://docs.particular.net/nservicebus/dependency-injection/<T>();方法中使用Invoke来解析IServiceScopeFactory之类的任何对象。IServiceScopeFactory已在DI容器中注册。例如，在端点初始化期间：endpointConfiguration.RegisterComponents(registration: x =>
{
x.ConfigureComponent<IServiceScopeFactory>(yourServiceScopeFactory);
});