Download an Azure blob container subfolder to a listview

[Scott]

I have the listview code for downloading the blob container. But I need to only get a subfolder in the container, not the whole thing. Is there a way to add the variable for the subfolder or should I structure the data in Azure differently and create a new container instead of using subfolders in one container?

public static async Task<List<string>> GetUploadedImages(AzureStorageConfig _storageConfig)
{
    List<ImageViewModel> images = new List<ImageViewModel>();

    // Create BlobServiceClient from the account URI
    BlobServiceClient blobServiceClient = new BlobServiceClient(_storageConfig.ConnectionString);

    // Get reference to the container
    BlobContainerClient container = blobServiceClient.GetBlobContainerClient(_storageConfig.ImageContainer);
    

    if (container.Exists())
    {
        var data = container.GetBlobs();
        foreach (BlobItem blobItem in container.GetBlobs())
        {
            images.Add(container.Uri + "/" + blobItem.Name);
        }
    }

    return await Task.FromResult(images);
}

[James]

In the GetBlobsAsync method there should be a prefix parameter which you can use like a path for the folder you're targeting, have you tried this?

 

var Container = await GetCloudBlobClientAsync();
await foreach (BlobItem blob in Container.GetBlobsAsync(BlobTraits.None, BlobStates.None, path))
{
  //do something with your blob
}

[Scott]

Thank you James, that is what I needed.

[Anislav]

Hi Scott,

Yes, you can retrieve only a specific "subfolder" from a blob container by leveraging Azure Storage's virtual directory concept. While Azure Blob Storage uses a flat namespace, you can simulate folders by including a delimiter (typically a /) in the blob names. This lets you organize and access blobs in a hierarchical manner.

To list blobs under a specific virtual directory (or "subfolder"), you can use the hierarchical listing approach and specify a prefix in your request corresponding to the subfolder path. This way, you're not required to create a separate container—just structure your blob names using slashes to mimic folders.

Here's a detailed example from the Azure docs: https://learn.microsoft.com/en-us/azure/storage/blobs/storage-blobs-list#use-a-hierarchical-listing

Regards,
Anislav Atanasov