带有 table 存储的 Azure 函数 - 更新实体不工作

Question

我有这个代码：

#r "Newtonsoft.Json"
#r "Microsoft.WindowsAzure.Storage"
using System;
using System.IO;
using System.Net.Http;
using Newtonsoft.Json;
using Microsoft.WindowsAzure.Storage.Table;
public async static void Run(string myIoTHubMessage, ICollector<SensorData> tableOutput, CloudTable activityTable,ICollector<SensorData> activityValue, ILogger log)
{
    var data = JsonConvert.DeserializeObject<IoTMessage>(myIoTHubMessage);
    string temp =  data.param2;
    double temperature = double.Parse(temp) * 0.01;

    var sensor = new SensorData { Temperature = temperature.ToString(),DeviceId = data.deviceId, RowKey = data.messageId, PartitionKey = data.deviceId };
    tableOutput.Add(sensor);

    var query = new TableQuery<SensorValue>().Where(TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, data.deviceId.ToString()));
    var segment = await activityTable.ExecuteQuerySegmentedAsync(query, null);

    if (segment.Results.Count == 0)
    {
        activityValue.Add(sensor);
    }
    else
    {
        SensorValue sensorValue = new SensorValue
        {
            PartitionKey = data.deviceId,
            RowKey = data.messageId,
            Temperature = Convert.ToInt16(temperature),
        };

        var operation = TableOperation.Replace(sensorValue);
        await activityTable.ExecuteAsync(operation);
        log.LogInformation(segment.Results.Count.ToString());
    }
}
public class SensorData
{
    public string RowKey { get; set; }
    public string PartitionKey { get; set; }
    public string Temperature { get; set; }
    public string DeviceId {get; set;}
}

public class IoTMessage
{
    public string messageId { get; set; }
    public string temperature { get; set; }
    public string deviceId { get; set; }

}

public class SensorValue : TableEntity
{
    public string RowKey { get; set; }
    public string PartitionKey { get; set; }
    public string Temperature { get; set; }
    public string DeviceId { get; set; }
}

该函数的工作方式是从传感器获取数据并将其保存到基地，但我想再做一个 table，其中只有给定设备的最后一个请求是保存。我检查 table 中是否有一个设备没有添加这样的 id，并且它可以正常工作。不幸的是，我在更新给定记录时遇到问题。在我看来是这样的：

   if (segment.Results.Count == 0)
        {
            activityValue.Add(sensor);
        }
        else
        {
            SensorValue sensorValue = new SensorValue
            {
                PartitionKey = data.deviceId,
                RowKey = data.messageId,
                Temperature = Convert.ToInt16(temperature),
            };

            var operation = TableOperation.Replace(sensorValue);
            await activityTable.ExecuteAsync(operation);
            log.LogInformation(segment.Results.Count.ToString());
        }

在 activityTable 中没有这样的设备的情况下记录自己 table 工作没有任何问题，不幸的是在有这样的设备的情况下更新不起作用，即没有错误，但也没有记录更新:(

在我的例子中，在 activityTable 中，PartitionKey 到 deviceId table 在请求中发送。我试着从早上 8 点开始，但没有任何效果，我无法处理它:(

Answer 1

快速解决方案：将 ETag 字段设置为 *，如您在 Azure 提示与技巧文章 Updating an item from a Azure Storage Table 中所见。

稍长的版本：根据 Table 存储，您尝试替换的实体不存在，因为您省略了 ETag 值。

An ETag property is used for optimistic concurrency during updates. It is not a timestamp as there is another property called TimeStamp that stores the last time a record was updated. For example, if you load an entity and want to update it, the ETag must match what is currently stored. This is important b/c if you have multiple users editing the same item, you don't want them overwriting each other's changes.

将ETag设置为*实际上是将其设置为接受任何值的通配符。

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