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Azure – How to access a virtual directory inside a blob container?

I am trying to download a file which is inside a subfolder of a blob container using Azure C# functions. This is all in a storage account.

BlobUriBuilder blobUriBuilder = new BlobUriBuilder(fileUri);  
string containerName = blobUriBuilder.BlobContainerName;
string blobName = blobUriBuilder.BlobName; 
BlobServiceClient blobServiceClient = new BlobServiceClient(connectionString);
BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(containerName);
BlobClient blobClient = containerClient.GetBlobClient(blobName);
// Check if the document exists
if (!await blobClient.ExistsAsync())
{
    return new NotFoundObjectResult(new { error = "Verify the file name", details = "Unable to locate the file in the provided location" });
} 
BlobDownloadInfo download = await blobClient.DownloadAsync();

I am able to download file from a root directory, but when I try to download a file inside a subfolder, it throws an error.

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2

Answers


  1. Chosen as BEST ANSWER
    0 
     BlobUriBuilder blobUriBuilder = new BlobUriBuilder(fileUri);

 string containerName = blobUriBuilder.BlobContainerName;

 // Split the BlobName into subfolder and blob name
 string[] pathParts = blobUriBuilder.BlobName.Split('/');

 // The first part is the subfolder, the rest is the blob name
 string subfolder = pathParts.Length > 1 ? pathParts[0] : null;
 string blobName = pathParts.Length > 1 ? string.Join('/', pathParts.Skip(1)) : pathParts[0];

 // If subfolder is not null, concatenate it with the blob name
 string blobPath = subfolder != null ? $"{subfolder}/{blobName}" : blobName;

 var blobServiceClient = new BlobServiceClient(connectionString);
 BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(containerName);
 BlobClient blobClient = containerClient.GetBlobClient(blobPath);

 // Check if the document exists
 if (!await blobClient.ExistsAsync())
 {
     return new NotFoundObjectResult(new { error = "Verify the file name", details = "Unable to locate the file in the provided location" });
 }

 BlobDownloadInfo download = await blobClient.DownloadAsync();

 string fileShareName = data.MoveFileRequest.TargetFileShareLocation.Split('/')[0];
 string targetSubfolder = data.MoveFileRequest.TargetFileShareLocation.Contains("/")
     ? data.MoveFileRequest.TargetFileShareLocation.Substring(data.MoveFileRequest.TargetFileShareLocation.IndexOf('/') + 1)
     : "";

 ShareClient shareClient = new ShareClient(connectionString, fileShareName);

 // Check if the file share exists
 if (!await shareClient.ExistsAsync())
 {
     return new NotFoundObjectResult(new { error = "Verify the target file share location", details = "Unable to move the file, File share does not exist in the directory" });
 }

 ShareDirectoryClient directoryClient = shareClient.GetRootDirectoryClient();

    This worked. Thanks guys for the input.


  2. 0

    I could achieve your requirement with below steps:

    • Uploaded a text file in the subfolder of my container in the Azure Storage Account:

    enter image description here

    • The file name along with the folder name should be passed in the GetBlobClient() as shown below:
    BlobClient blobClient = containerClient.GetBlobClient($"{subfolderName}/{fileName}");

    My Code Snippet:

    var connectionString = "<storage_connection_string>";
var url = "https://<storage>.blob.core.windows.net/<Blob_name>/<Folder1>/<folder2><file.exe>";
BlobUriBuilder blobUriBuilder = new BlobUriBuilder(new Uri(url));
string containerName = blobUriBuilder.BlobContainerName;
string blobName = blobUriBuilder.BlobName;
BlobServiceClient blobServiceClient = new BlobServiceClient(connectionString);
BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(containerName);
BlobClient blobClient = containerClient.GetBlobClient(blobName);

if (!await blobClient.ExistsAsync())
{
    return new NotFoundObjectResult(new { error = "Verify the file name", details = "Unable to locate the file in the provided location" });
}
BlobDownloadResult downloadResult = await blobClient.DownloadContentAsync();
string downloadedData = downloadResult.Content.ToString();
log.LogInformation("Downloaded data: " + downloadedData);
    • In this case, BlobName contains the full path of the blob within the directory/folder. i.e., "subfolder/file.exe".

    enter image description here

    Console Output:

    • Able to read the content of the downloaded file.
    Azure Functions Core Tools
Core Tools Version:       4.0.5530 Commit hash: N/A +c8883e7f3c06e2XXXX3806c19d8d91418c (64-bit)
Function Runtime Version: 4.28.5.21962

[2024-03-07T11:48:50.219Z] Found C:Usersuname...FunctionApp.csproj. Using for user secrets file configuration.

Functions:

        Function1: [GET,POST] http://localhost:7236/api/Function1

For detailed output, run func with --verbose flag.
[2024-03-07T12:11:43.018Z] Host lock lease acquired by instance ID '000000000000000000000000F72731CC'.
[2024-03-07T12:11:59.840Z] Executing 'Function1' (Reason='This function was programmatically called via the host APIs.', Id=5744c98b-ccXXX8f-fb4cfe85d25b)
[2024-03-07T12:11:59.941Z] C# HTTP trigger function processed a request.
[2024-03-07T12:12:22.316Z] Downloaded data: Secret-1
[2024-03-07T12:12:22.333Z] Secret-2
[2024-03-07T12:12:22.344Z] Secret-3
[2024-03-07T12:12:22.546Z] Executed 'Function1' (Succeeded, Id=5744c98b-cca6-43XXXXX4cfe85d25b, Duration=22797ms)
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