WebJob 依赖注入绑定到泛型 Class

Question

我有一系列类用于处理看起来像这样的 WebJobs：

public class EnvelopeSalutationJob : BatchJob
{
    public EnvelopeSalutationJob( StringWriter swLogger )
        : base( swLogger, "Envelope Salutation Job" )
    {
    }

    [ Singleton() ]
    public async Task ProcessMessage(
        [ QueueTrigger( "%" + nameof( ContainerQueueConstants.EnvelopeSalutation ) + "%" ) ] EnvelopeSalutationMessage msg,
        TextWriter azureLogWriter
    )
    {
        PhaseNames.SetNames( "Processing Homes", "Job Completed" );

        await ExecuteFromMessage( msg, azureLogWriter, Launch );
    }
}

这些使用 AutoFac 作为 DI 框架时效果很好，配置如下所示：

public static class ContainerConfig
{
    public static IContainer GetContainer()
    {
        var builder = new ContainerBuilder();

        // per job
        builder.RegisterType<StringWriter>();

        // jobs
        builder.RegisterType<EnvelopeSalutationJob>();

        return builder.Build();
    }
}

但最近我想 "genericize" 作业，这样它们就不会绑定到特定的 DbContext。我尝试使用这样的模式：

public class EnvelopeSalutationJob<TContext, TUser>
    : BatchJob<TContext, TUser>
    where TContext : IdentityDbContext<TUser>, ICampaignContext, new()
    where TUser : IdentityUser, INamedUser
{
    public EnvelopeSalutationJob( StringWriter swLogger )
        : base( swLogger, "Envelope Salutation Job" )
    {
    }
    [ Singleton() ]
    public async Task ProcessMessage(
        [ QueueTrigger( "%" + nameof( ContainerQueueConstants.EnvelopeSalutation ) + "%" ) ] EnvelopeSalutationMessage msg,
        TextWriter azureLogWriter
    )
    {
        PhaseNames.SetNames( "Processing Homes", "Job Completed" );

        await ExecuteFromMessage( msg, azureLogWriter, Launch );
    }
}

AutoFac 配置更改为：

public static class ContainerConfig
{
    public static IContainer GetContainer()
    {
        var builder = new ContainerBuilder();

        // per job
        builder.RegisterType<StringWriter>();

        // jobs
        builder.RegisterType<EnvelopeSalutationJob<ConnellJobContext, ConnellUser>>();

        return builder.Build();
    }
}

不幸的是，这不起作用。 WebJobs 控制台应用程序启动正常，但它抱怨：

No job functions found. Try making your job classes and methods public.

是否无法将作业绑定到通用实例类？

Answer 1

根据你的描述，我已经在我这边测试了这个问题，我可以重现这个问题，如下所示：

我勾选Azure WebJobs SDK source code on git, I found that DefaultTypeLocator.cs would use IsJobClass that invoking Type.ContainsGenericParameters过滤类型后如下：

public static bool IsJobClass(Type type)
{
    if (type == null)
    {
        return false;
    }

    return type.IsClass
        // For C# static keyword classes, IsAbstract and IsSealed both return true. Include C# static keyword
        // classes but not C# abstract keyword classes.
        && (!type.IsAbstract || type.IsSealed)
        // We only consider public top-level classes as job classes. IsPublic returns false for nested classes,
        // regardless of visibility modifiers. 
        && type.IsPublic
        && !type.ContainsGenericParameters;
}

此外，FunctionIndexer.cs 将使用 IsJobMethod 过滤方法如下：

public bool IsJobMethod(MethodInfo method)
{
    if (method.ContainsGenericParameters)
    {
        return false;
    }

    if (method.GetCustomAttributesData().Any(HasJobAttribute))
    {
        return true;
    }

    if (method.GetParameters().Length == 0)
    {
        return false;
    }

    if (method.GetParameters().Any(p => p.GetCustomAttributesData().Any(HasJobAttribute)))
    {
        return true;
    }

    return false;
}

据我了解，Azure WebJobs SDK 目前不支持将作业绑定到通用类的实例。您可以定义 BaseDbContext 并利用构造函数依赖注入来初始化 DbContext 实例。另外，您可以添加您的反馈 here.

WebJob 依赖注入绑定到泛型 Class

WebJob Dependency Injection Binding to Generic Class

c#

generics

azure-webjobs