无法在C#中访问Amazon SQS消息属性

Question

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主体的内容和属性执行某些逻辑。

我可以成功地在SQS队列上创建一个带有正文和属性的消息，但是我在回读消息属性时出现了问题！

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回那些属性。

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);

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！当直接使用SQS队列手动创建消息时，我也有同样的问题。我想不通为什么？任何帮助都会很好。非常感谢,

Answer 1

好吧，我想出了这一招。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;

以上对我有效。希望对某人有用...