无法在c#中访问Amazon SQS消息属性

本文关键字：Amazon SQS 消息 属性 访问 | 更新日期: 2023-09-27 18:02:29

我有一个进程创建SQS消息并将其放置在SQS队列中，另一个进程读取这些消息并根据消息体的内容和属性执行某些逻辑。

我可以成功地在具有主体和属性的SQS队列上创建消息，但是我在读取消息属性时遇到了问题!

我确信我的消息创建过程是正确的，我可以在AWS SQS控制台中看到队列的属性。我只是不明白为什么我不能读取这些属性。

创建消息的代码:

IAmazonSQS sqs = AWSClientFactory.CreateAmazonSQSClient();
var sendMessageRequest = new SendMessageRequest();
sendMessageRequest.QueueUrl = "myURL";
Dictionary<string, MessageAttributeValue> MessageAttributes = new Dictionary<string, MessageAttributeValue>();
MessageAttributeValue messageTypeAttribute = new MessageAttributeValue();
messageTypeAttribute.DataType = "String";
messageTypeAttribute.StringValue = "HIGH";
MessageAttributes.Add("MESSAGEPRIORITY", messageTypeAttribute);
sendMessageRequest.MessageAttributes = MessageAttributes;
sendMessageRequest.MessageBody = "Thats the message body";
sqs.SendMessage(sendMessageRequest);

上面的工作和一个具有messagpriority =HIGH属性的消息被创建(我可以在SQS控制台看到消息和属性)。

当读取回消息时(我跳过了显示队列URL等的部分代码):

IAmazonSQS sqs = AWSClientFactory.CreateAmazonSQSClient();
ReceiveMessageResponse receiveMessage = new ReceiveMessageResponse();
ReceiveMessageRequest request = new ReceiveMessageRequest();
request.QueueUrl = "myURL";
receiveMessage = sqs.ReceiveMessage(request);
string messageBody = receiveMessage.Messages[0].Body;
Dictionary<string, MessageAttributeValue> messageAttributes = receiveMessage.Messages[0].MessageAttributes;
使用上面的代码，我得到了消息的正文，但是属性是空的!在直接使用SQS队列手动创建消息时，我也遇到了同样的问题。我不知道为什么?任何帮助都太好了。多谢,

无法在c#中访问Amazon SQS消息属性

好了，我算出来了。在调用提取消息之前，需要将属性名称指定为ReceiveMessageRequest对象的属性。

因此，上面的代码需要更改为: 
IAmazonSQS sqs = AWSClientFactory.CreateAmazonSQSClient();
ReceiveMessageResponse receiveMessage = new ReceiveMessageResponse();
ReceiveMessageRequest request = new ReceiveMessageRequest();
//Specify attribute list
List<string> AttributesList = new List<string>();
AttributesList.Add("MESSAGEPRIORITY");
//Assign list and QueueURL to request
request.MessageAttributeNames = AttributesList;
request.QueueUrl = "myURL";
//Receive the message...
receiveMessage = sqs.ReceiveMessage(request);
//Body...
string messageBody = receiveMessage.Messages[0].Body;
//...and attributes
Dictionary<string, MessageAttributeValue> messageAttributes = receiveMessage.Messages[0].MessageAttributes;

以上内容适用于我。希望对大家有用....

要检索消息的所有属性而不指定每个属性，您可以在属性列表中添加"*"或" all "。像这样:

//Specify attribute list
List<string> AttributesList = new List<string>();
AttributesList.Add("*");

AWS SQS ReceiveMessage文档

从SQS中读取的完整方法

    public async Task ReadFromSQS()
    {
        IAmazonSQS sqs = new AmazonSQSClient(RegionEndpoint.EUWest1);
        try
        {
            List<string> AttributesList = new List<string>();
            AttributesList.Add("NameOfTheAttribute");
            ReceiveMessageRequest receiveMessageRequest = new ReceiveMessageRequest();
            receiveMessageRequest.QueueUrl = IdQueue;
            receiveMessageRequest.MessageAttributeNames = AttributesList;
            ReceiveMessageResponse receiveMessageResponse = await sqs.ReceiveMessageAsync(receiveMessageRequest);
            foreach (Message message in receiveMessageResponse.Messages)
            {
                Debug.WriteLine("Body: "+ message.Body);
                Debug.WriteLine("Values: " + message.MessageAttributes.Count);
                foreach (var entry in message.MessageAttributes)
                {
                    Debug.WriteLine("Attribute");
                    Debug.WriteLine("Name: "+ entry.Key);
                    Debug.WriteLine("Value1: "+ entry.Value.StringValue);
                }
            }
            String messageRecieptHandle = receiveMessageResponse.Messages[0].ReceiptHandle;
            //Deleting a message
            Debug.WriteLine("Deleting the message.'n");
            DeleteMessageRequest deleteRequest = new DeleteMessageRequest();
            deleteRequest.QueueUrl = IdQueue;
            deleteRequest.ReceiptHandle = messageRecieptHandle;
            await sqs.DeleteMessageAsync(deleteRequest);
        }
        catch (AmazonSQSException ex)
        {
            Debug.WriteLine("Caught Exception: " + ex.Message);
            Debug.WriteLine("Response Status Code: " + ex.StatusCode);
            Debug.WriteLine("Error Code: " + ex.ErrorCode);
            Debug.WriteLine("Error Type: " + ex.ErrorType);
            Debug.WriteLine("Request ID: " + ex.RequestId);
        }
        Debug.WriteLine("Press Enter to continue...");
        Console.Read();
    }
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