Question

我有一个需要拦截当前消息使用上下文并提取在基本接口中定义的值的应用程序。该值是最终在EF数据库上下文中使用的租户代码。

我有一个采用MassTransit ConsumerContext的提供程序，然后使用context.TryGetMessage()提取承租人代码，最终将其用于将数据库上下文切换到特定的承租人数据库。

问题出在下面的MessageContextTenantProvider中。如果使用了非故障消息，则ConsumeContext<IBaseEvent>可以正常工作。但是，如果是故障，则ConsumeContext<Fault<IBaseEvent>>不能按预期工作。

进行调试时，我可以看到故障的消息上下文是ConsumeContext<Fault<IVerifyEvent>>，但是为什么它不能按照标准消息与基本接口一起使用？当然，ConsumeContext<Fault<IVerifiedEvent>>可以很好地工作，但是我有很多消息类型，并且我不想在租户提供程序中全部定义它们。

有什么想法吗？

public interface ITenantProvider
{
    string GetTenantCode();
}

public class MessageContextTenantProvider : ITenantProvider
{
    private readonly ConsumeContext _consumeContext;

    public MessageContextTenantProvider(ConsumeContext consumeContext)
    {
        _consumeContext = consumeContext;
    }

    public string GetTenantCode()
    {
        // get tenant from message context
        if (_consumeContext.TryGetMessage(out ConsumeContext<IBaseEvent> baseEvent))
        {
            return baseEvent.Message.TenantCode; // <-- works for the non fault consumers
        }

        // get tenant from fault message context
        if (_consumeContext.TryGetMessage<Fault<IBaseEvent>>(out var gebericFaultEvent))
        {
            return gebericFaultEvent.Message.Message.TenantCode; // <- doesn't work generically
        }

        // get tenant from fault message context (same as above)
        if (_consumeContext.TryGetMessage(out ConsumeContext<Fault<IBaseEvent>> faultEvent))
        {
            return faultEvent.Message.Message.TenantCode; // <= generically doesn't work when using the base interface?
        }

        // get tenant from specific concrete fault class
        if (_consumeContext.TryGetMessage(out ConsumeContext<Fault<IVerifiedEvent>> verifiedFaultEvent))
        {
            return verifiedFaultEvent.Message.Message.TenantCode; // <-- this works
        }

        // not able to extract tenant
        return null;
    }
}

public partial class VerificationDbContext
{
    string connectionString;

    public string ConnectionString
    {
        get
        {
            if (connectionString == null)
            {
                string tenantCode = _tenantProvider.GetTenantCode();
                connectionString = _tenantConnectionManager.GetConnectionString(orgId);
            }
            return connectionString;
        }
    }

    private readonly ITenantProvider _tenantProvider;

    private readonly ITenantConnectionManager _tenantConnectionManager;

    public VerificationDbContext(ITenantProvider tenantProvider, ITenantConnectionManager tenantConnectionManager)
    {
        _tenantProvider = tenantProvider;
        _tenantConnectionManager = tenantConnectionManager;
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (string.IsNullOrEmpty(this.ConnectionString))
        {
            optionsBuilder.UseSqlServer(@"Data Source=.\SQLEXPRESS;Initial Catalog=VerificationDb;Integrated Security=True")
                .ConfigureWarnings((warningBuilder) => warningBuilder.Ignore(RelationalEventId.AmbientTransactionWarning));
        }
        else
        {
            optionsBuilder.UseSqlServer(this.ConnectionString)
                .ConfigureWarnings((warningBuilder) => warningBuilder.Ignore(RelationalEventId.AmbientTransactionWarning));
        }
    }
}

public interface ITenantConnectionManager
{
    string GetConnectionString(string tenantCode);
}

public class TenantConnectionManager : ITenantConnectionManager
{
    private ITenantRepository _tenantRepository;

    public TenantConnectionManager(ITenantRepository tenantRepository)
    {
        _tenantRepository = tenantRepository;
    }

    public string GetConnectionString(string tenantCode)
    {
        return _tenantRepository.GetByTenantCode(tenantCode).ConnectionString;
    }
}

public interface IBaseEvent
{
    string TenantCode { get; }
}

public interface IVerifiedEvent : IBaseEvent
{
    string JobReference { get; }
}

public class VerifiedEventConsumer : IConsumer<IVerifiedEvent>
{
    private readonly IVerifyCommand _verifyCommand;

    private readonly ITenantProvider _tenantProvider;

    public VerifiedEventConsumer(ITenantProvider tenantProvider, IVerifyCommand verifyCommand)
    {
        _verifyCommand = verifyCommand;
        _tenantProvider = tenantProvider;
    }

    public async Task Consume(ConsumeContext<IVerifiedEvent> context)
    {
        await _verifyCommand.Execute(new VerifyRequest
        {
            JobReference = context.Message.JobReference,
            TenantCode = context.Message.TenantCode
        });
    }
}

public class VerifiedEventFaultConsumer : IConsumer<Fault<IVerifiedEvent>>
{
    private readonly IVerifyFaultCommand _verifyFaultCommand;

    private readonly ITenantProvider _tenantProvider;

    public CaseVerifiedEventFaultConsumer(ITenantProvider tenantProvider, IVerifyFaultCommand verifyFaultCommand)
    {
        _verifyFaultCommand = verifyFaultCommand;
        _tenantProvider = tenantProvider;
    }

    public async Task Consume(ConsumeContext<Fault<ICaseVerifiedEvent>> context)
    {
        await _verifyFaultCommand.Execute(new VerifiedFaultRequest
        {
            JobReference = context.Message.Message.JobReference,
            Exceptions = context.Message.Exceptions
        });
    }
}

Answer 1

我已经通过使用GreenPipes TryGetPayload扩展方法解决了这个问题：

public class MessageContextTenantProvider : ITenantProvider
{
    private readonly ConsumeContext _consumeContext;

    public MessageContextTenantProvider(ConsumeContext consumeContext)
    {
        _consumeContext = consumeContext;
    }

    public string GetTenantCode()
    {
        // get tenant from message context
        if (_consumeContext.TryGetMessage(out ConsumeContext<IBaseEvent> baseEvent))
        {
            return baseEvent.Message.TenantCode;
        }

        // get account code from fault message context using Greenpipes
        if (_consumeContext.TryGetPayload(out ConsumeContext<Fault<IBaseEvent>> payloadFaultEvent))
        {
            return payloadFaultEvent.Message.Message.TenantCode;
        }

        // not able to extract tenant
        return null;
    }
}

在Masstransit中从消息上下文获取错误消息的问题

1 个答案: