C# 如何使用输出绑定而不必赋值？

如何在不强制为输出绑定赋值的情况下指定输出绑定

我能够成功地使用以下属性绑定到2个输出blob位置：

        [Blob("processed/{CorrelationId}", FileAccess.Write, Connection = "OnSchedulingToMMMQueueTriggered:ProcessedPayloadsConnectionString")] out string processedPayload,
        [Blob("success/{CorrelationId}", FileAccess.Write, Connection = "OnSchedulingToMMMQueueTriggered:ProcessedPayloadsConnectionString")] out string success,

但是，由于我没有将任何内容分配给此值out string success，因此出现以下异常：

如何在不强制为输出绑定赋值的情况下指定输出绑定在某些情况下，我不希望分配任何值，因为我只是不想写入该blob

我的全部职能如下：

public static class OnSchedulingToMMMQueueTriggered
{
    [FunctionName("OnSchedulingToMMMQueueTriggered")]
    public static void Run(
        [QueueTrigger("httpqueue", Connection = "OnSchedulingToMMMQueueTriggered:SourceQueueConnection")] Payload myQueueItem,
        [Blob("processed/{CorrelationId}", FileAccess.Write, Connection = "OnSchedulingToMMMQueueTriggered:ProcessedPayloadsConnectionString")] out string processedPayload,
        [Blob("success/{CorrelationId}", FileAccess.Write, Connection = "OnSchedulingToMMMQueueTriggered:ProcessedPayloadsConnectionString")] out string success,
        ILogger log)
    {
        log.LogInformation($"C# Queue trigger function processed: {myQueueItem.Body}");

        processedPayload = "this shoudl be the body of the string";
    }
}

---

如果使用特定的out参数，它将需要它。如果输出是有条件的，考虑只创建一个BulbCube绑定，只在需要时使用它。这将要求您自己使用GetBlockBlobReference创建blob，但这只是解决这个问题的一点额外代码。我还没有机会测试下面的代码，所以您可能需要稍微调整一下

public static class OnSchedulingToMMMQueueTriggered
{
    [FunctionName("OnSchedulingToMMMQueueTriggered")]
    public static void Run(
        [QueueTrigger("httpqueue", Connection = "OnSchedulingToMMMQueueTriggered:SourceQueueConnection")] Payload myQueueItem,
        [Blob("processed/{CorrelationId}", FileAccess.Write, Connection = "OnSchedulingToMMMQueueTriggered:ProcessedPayloadsConnectionString")] out string processedPayload,
        [Blob("success", FileAccess.Write, Connection = "OnSchedulingToMMMQueueTriggered:ProcessedPayloadsConnectionString"))] CloudBlobContainer outputSuccessContainer,
        ILogger log)
    {
        log.LogInformation($"C# Queue trigger function processed: {myQueueItem.Body}");

        processedPayload = "this shoudl be the body of the string";

        if (outputNeeded) {
            var blockBlob = outputSuccessContainer.GetBlockBlobReference(CorrelationId + ".txt");
            await blockBlob.UploadText(processedPayload);
            blockBlob.Properties.ContentType = "text/plain";
            blockBlob.SetProperties();
        }
    }
}

---

我猜我需要执行outputSuccessContainer.CreateIfNotExistsAsync；首先在运行UploadTextAsync之前？是的，如果您不能确定所引用的容器是否已经存在，那么最好调用await outputSuccessContainer.CreateIfNotExistsAsync；