Question

我正在将Azure Function应用程序与服务总线触发器一起使用，以读取服务总线并处理服务总线消息的内容。服务总线接收JSON序列化的对象，然后我将JSON消息反序列化回Function App中的对象。但是，由于某种原因，每当有东西发送到服务总线时，触发器就会触发两次，其中一个是JSON消息，另一个是包含“服务总线消息”文本的消息。

我不知道是什么导致第二条消息，所以我想到的只是反序列化服务总线消息，当它因“服务总线消息”而失败时，我将捕获异常并忽略它。但是，我认为这不是处理此问题的正确方法，JSON反序列化中的实际错误将被忽略。处理第二条消息的正确方法是什么？

示例代码：

using Newtonsoft.Json;

public static void Run(string myQueueItem, ILogger log, out SendGridMessage mailMessage)
{
    MyClass myObject = null;
    try
    {
        myObject = JsonConvert.DeserializeObject<MyClass>(myQueueItem);
        // do stuff
    }
    catch (JsonException je)
    {
        // ignore this exception
    }
    catch (Exception e)
    {
        // handle the other exceptions and send an alert
    }
}

编辑：在原始文章中我没有提到的一件事是我也有一个SendGrid输出。我不知道为什么这会对触发器产生什么影响，所以我将其遗漏了。但是，我现在添加它，以防万一它可能是出于某些奇怪的原因。

编辑2：添加了突出显示该问题的完整工作代码

// Sender
using System;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Azure.ServiceBus;
using Newtonsoft.Json;

namespace myapp
{
    class Program
    {
        static void Main(string[] args) => MainAsync().GetAwaiter().GetResult();

        static async Task MainAsync()
        {
            string serviceBusConnectionString = "<your servicebus connectionstring>";
            string queueName = "<your queue name>";
            IQueueClient queueClient = new QueueClient(serviceBusConnectionString, queueName);
            string messageBody = JsonConvert.SerializeObject(new Test());
            var message = new Message(Encoding.UTF8.GetBytes(messageBody));
            await queueClient.SendAsync(message);
            await queueClient.CloseAsync();
        }

        class Test
        {
            public string Text { get; set; } = "test";
        }
    }
}

// Receiver
#r "Newtonsoft.Json"

using System;
using System.Threading.Tasks;
using Newtonsoft.Json;

public static void Run(string myQueueItem, ILogger log)
{
    try
    {
        Test test = JsonConvert.DeserializeObject<Test>(myQueueItem);
        log.LogInformation($"C# ServiceBus queue trigger function processed message: {test.Text}");
    }
    catch (Exception e)
    {
        log.LogInformation($"Exception: {e.Message}");
    }
}

class Test
{
    public string Text { get; set; } = "test";
}

结果：

2019-11-04T08:38:10.544 [Information] Executing 'Functions.test' (Reason='This function was programmatically called via the host APIs.', Id=06e10006-baa6-430f-b5db-9a5eae5c154c)
2019-11-04T08:38:10.659 [Information] Exception: Unexpected character encountered while parsing value: S. Path '', line 0, position 0. // This here is caused by "Service bus message"
2019-11-04T08:38:10.659 [Information] Executed 'Functions.test' (Succeeded, Id=06e10006-baa6-430f-b5db-9a5eae5c154c)
2019-11-04T08:39:02.582 [Information] Executing 'Functions.test' (Reason='New ServiceBus message detected on 'test'.', Id=5d7622a7-cc8d-44c9-8720-626fdbb8cabb)
2019-11-04T08:39:02.583 [Information] Trigger Details: MessageId: 13bba779fd524fa1a0098acd6634aded, DeliveryCount: 1, EnqueuedTime: 11/4/2019 8:39:02 AM, LockedUntil: 11/4/2019 8:39:07 AM
2019-11-04T08:39:02.584 [Information] C# ServiceBus queue trigger function processed message: test // This here is the actual message
2019-11-04T08:39:02.584 [Information] Executed 'Functions.test' (Succeeded, Id=5d7622a7-cc8d-44c9-8720-626fdbb8cabb)

Answer 1

根据我的测试，触发器不会被触发两次。

namespace ServiceBusTrigger
{
    public static class Function1
    {
        [FunctionName("Function1")]
        public static void Run([ServiceBusTrigger("myqueue", Connection = "ServiceBusConnection")]string myQueueItem, ILogger log)
        {
            log.LogInformation($"C# ServiceBus queue trigger function processed message: {myQueueItem}");

            var myMessage = JsonConvert.DeserializeObject<MyMessage>(myQueueItem);

            log.LogInformation($"ID: {myMessage.id}\tContent:{myMessage.content}");
        }
    }
}

手动发送消息，并获得以下输出：


Pause Clear Expand

2019-11-04T08:18:56.837 [Information] Executing 'Function1' (Reason='New ServiceBus message detected on 'myqueue'.', Id=7fb37483-b9a3-4c19-baa3-235b419bb585)
2019-11-04T08:18:56.837 [Information] Trigger Details: MessageId: c00a8e41-d883-4620-992f-6b9b4fdae320, DeliveryCount: 1, EnqueuedTime: 11/4/2019 8:18:56 AM, LockedUntil: 11/4/2019 8:19:26 AM
2019-11-04T08:18:56.838 [Information] C# ServiceBus queue trigger function processed message: {"id":"1","content":"abc"}
2019-11-04T08:18:56.838 [Information] ID: 1 Content:abc
2019-11-04T08:18:56.839 [Information] Executed 'Function1' (Succeeded, Id=7fb37483-b9a3-4c19-baa3-235b419bb585)

那么，您能否检查您的服务总线生产商以查看是否发送了其他消息。

您只能停止功能应用程序，手动发送消息并在门户上检查：

如果一切正常，则应该只有1条活动消息。

更新

Azure Function App Azure服务总线触发器两次触发

1 个答案: