使用GetBlobReference时（Azure存储CloudBlob.Properties不会被初始化） [英] Azure Storage CloudBlob.Properties are not initialized when using GetBlobReference()

问题描述

我试图获得关于Azure的BLOB（最后修改UTC日期时间）的一些信息。这个信息被存储CloudBlob.Properties.LastModifiedUtc属性

如果我使用的方法GetBlobReference（）或GetBlockBlobReference（），BLOB的属性不会被初始化（LastModifiedUtc是DateTime.MinDate）。如果我使用ListBlobs（）属性的正确初始化（LastModifiedUtc有正确的值）。

使用GetBlobReference功能时，难道我做错了什么？有一些路怎么走CloudBlob实例只为一个特定的斑点？我知道我可以missue ListBlobs（）和过滤只是一滴我感兴趣的，或者使用从类CloudBlobClient ListBlobsWith preFIX（），但我希望让所有的元数据时，我问具体的斑点参考。

code展示我如何与Azure的斑点工作：

 字符串storageAccountName =测试;
    字符串storageAccountKey = @密押
    字符串blobUrl =htt​​ps://test.blob.core.windows.net;
    字符串容器名称=testcontainer;
    字符串blobName =testbontainer;    VAR证书=新StorageCredentialsAccountAndKey（storageAccountName，storageAccountKey）;
    VAR cloudBlobClient =新CloudBlobClient（blobUrl，证书）;
    VAR containerReference = cloudBlobClient.GetContainerReference（的String.Format（{0} / {1}，blobUrl，容器名称））;    // OK  - 结果类型CloudBlockBlob的，cloudBlob_ListBlobs.Properties.LastModifiedUtc＆GT; DateTime.MinValue
    变种cloudBlob_ListBlobs = containerReference.ListBlobs（）式（I = I标记是CloudBlob＆放大器;及（（CloudBlob）ⅰ）.Name点== blobName）。.FirstOrDefault（）作为CloudBlob;    // WRONG  - 结果类型CloudBlob的，cloudBlob_GetBlobReference.Properties.LastModifiedUtc == DateTime.MinValue
    VAR cloudBlob_GetBlobReference = containerReference.GetBlobReference（的String.Format（{0} / {1} / {2}，blobUrl，容器名称，blobName））;    // WRONG  - 结果类型CloudBlockBlob的，cloudBlob_GetBlockBlobReference.Properties.LastModifiedUtc == DateTime.MinValue
    VAR cloudBlob_GetBlockBlobReference = containerReference.GetBlockBlobReference（的String.Format（{0} / {1} / {2}，blobUrl，容器名称，blobName））;
 

解决方案

我相信你必须做出一个单独的调用来获取属性/元。之后，你有团块参鉴，发出以下行来检索的属性。

cloudBlob_GetBlobReference.FetchAttributes（）;

I'm trying to get some information about Azure blob (last modified UTC date time). This information is stored CloudBlob.Properties.LastModifiedUtc property.

If I use method GetBlobReference() or GetBlockBlobReference(), the Properties of the blob are not initialized (LastModifiedUtc is DateTime.MinDate). If I use ListBlobs() the Properties are initialized correctly (LastModifiedUtc has correct value).

Am I doing something wrong when using GetBlobReference function? Is there some way how to get CloudBlob instance just for one specific blob? I know I can missue ListBlobs() and filter just the blob I'm interested in, or use ListBlobsWithPrefix() from class CloudBlobClient, but I would expect to get all the metadata when I ask for specific Blob Reference.

Code showing how I'm working with Azure blobs:

    string storageAccountName = "test";
    string storageAccountKey = @"testkey";
    string blobUrl = "https://test.blob.core.windows.net";
    string containerName = "testcontainer";
    string blobName = "testbontainer";

    var credentials = new StorageCredentialsAccountAndKey(storageAccountName, storageAccountKey);
    var cloudBlobClient = new CloudBlobClient(blobUrl, credentials);
    var containerReference = cloudBlobClient.GetContainerReference(string.Format("{0}/{1}", blobUrl, containerName));

    // OK - Result is of type CloudBlockBlob, cloudBlob_ListBlobs.Properties.LastModifiedUtc > DateTime.MinValue
    var cloudBlob_ListBlobs = containerReference.ListBlobs().Where(i => i is CloudBlob && ((CloudBlob)i).Name == blobName).FirstOrDefault() as CloudBlob;

    // WRONG - Result is of type CloudBlob, cloudBlob_GetBlobReference.Properties.LastModifiedUtc == DateTime.MinValue
    var cloudBlob_GetBlobReference = containerReference.GetBlobReference(string.Format("{0}/{1}/{2}", blobUrl, containerName, blobName));

    // WRONG - Result is of type CloudBlockBlob, cloudBlob_GetBlockBlobReference.Properties.LastModifiedUtc == DateTime.MinValue
    var cloudBlob_GetBlockBlobReference = containerReference.GetBlockBlobReference(string.Format("{0}/{1}/{2}", blobUrl, containerName, blobName));

解决方案

I believe you have to make a seperate call to fetch the attributes/metadata. After you have the blob referrence, issue the following line to retrieve the attributes.

cloudBlob_GetBlobReference.FetchAttributes();

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