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Delete and restore a blob with .NET

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This article shows how to delete blobs with the Azure Storage client library for .NET. If you've enabled soft delete for blobs, you can restore deleted blobs during the retention period.

Prerequisites

  • This article assumes you already have a project set up to work with the Azure Blob Storage client library for .NET. To learn about setting up your project, including package installation, adding using directives, and creating an authorized client object, see Get started with Azure Blob Storage and .NET.
  • The authorization mechanism must have permissions to delete a blob, or to restore a soft-deleted blob. To learn more, see the authorization guidance for the following REST API operations:

Delete a blob

To delete a blob, call either of these methods:

The following example deletes a blob:

public static async Task DeleteBlobAsync(BlobClient blob)
{
    await blob.DeleteAsync();
}

If the blob has any associated snapshots, you must delete all of its snapshots to delete the blob. The following example deletes a blob and its snapshots:

public static async Task DeleteBlobSnapshotsAsync(BlobClient blob)
{
    // Delete a blob and all of its snapshots
    await blob.DeleteAsync(snapshotsOption: DeleteSnapshotsOption.IncludeSnapshots);

    // Delete only the blob's snapshots
    //await blob.DeleteAsync(snapshotsOption: DeleteSnapshotsOption.OnlySnapshots);
}

To delete only the snapshots and not the blob itself, you can pass the parameter DeleteSnapshotsOption.OnlySnapshots.

Restore a deleted blob

Blob soft delete protects an individual blob and its versions, snapshots, and metadata from accidental deletes or overwrites by maintaining the deleted data in the system for a specified period of time. During the retention period, you can restore the blob to its state at deletion. After the retention period has expired, the blob is permanently deleted. For more information about blob soft delete, see Soft delete for blobs.

You can use the Azure Storage client libraries to restore a soft-deleted blob or snapshot.

How you restore a soft-deleted blob depends on whether or not your storage account has blob versioning enabled. For more information on blob versioning, see Blob versioning. See one of the following sections, depending on your scenario:

Restore soft-deleted objects when versioning is disabled

To restore deleted blobs when versioning is not enabled, call either of the following methods:

These methods restore soft-deleted blobs and any deleted snapshots associated with them. Calling either of these methods for a blob that has not been deleted has no effect. The following example restores all soft-deleted blobs and their snapshots in a container:

public static async Task RestoreBlobsAsync(BlobContainerClient container)
{
    foreach (BlobItem blob in container.GetBlobs(BlobTraits.None, BlobStates.Deleted))
    {
        await container.GetBlockBlobClient(blob.Name).UndeleteAsync();
    }
}

To restore a specific soft-deleted snapshot, first call the Undelete or UndeleteAsync on the base blob, then copy the desired snapshot over the base blob. The following example restores a block blob to the most recently generated snapshot:

public static async Task RestoreSnapshotsAsync(
    BlobContainerClient container,
    BlobClient blob)
{
    // Restore the deleted blob
    await blob.UndeleteAsync();

    // List blobs in this container that match prefix
    // Include snapshots in listing
    Pageable<BlobItem> blobItems = container.GetBlobs(
        BlobTraits.None,
        BlobStates.Snapshots,
        prefix: blob.Name);

    // Get the URI for the most recent snapshot
    BlobUriBuilder blobSnapshotUri = new BlobUriBuilder(blob.Uri)
    {
        Snapshot = blobItems
            .OrderByDescending(snapshot => snapshot.Snapshot)
            .ElementAtOrDefault(0)?.Snapshot
    };

    // Restore the most recent snapshot by copying it to the blob
    await blob.StartCopyFromUriAsync(blobSnapshotUri.ToUri());
}

Restore soft-deleted blobs when versioning is enabled

If a storage account is configured to enable blob versioning, deleting a blob causes the current version of the blob to become the previous version. To restore a soft-deleted blob when versioning is enabled, copy a previous version over the base blob. You can use either of the following methods:

The following code example shows how to get the latest version of a deleted blob, and restore the latest version by copying it to the base blob:

public static void RestoreBlobWithVersioning(
    BlobContainerClient container,
    BlobClient blob)
{
    // List blobs in this container that match prefix
    // Include versions in listing
    Pageable<BlobItem> blobItems = container.GetBlobs(
        BlobTraits.None,
        BlobStates.Version,
        prefix: blob.Name);

    // Get the URI for the most recent version
    BlobUriBuilder blobVersionUri = new BlobUriBuilder(blob.Uri)
    {
        VersionId = blobItems.
            OrderByDescending(version => version.VersionId).
            ElementAtOrDefault(0)?.VersionId
    };

    // Restore the most recently generated version by copying it to the base blob
    blob.StartCopyFromUri(blobVersionUri.ToUri());
}

Resources

To learn more about how to delete blobs and restore deleted blobs using the Azure Blob Storage client library for .NET, see the following resources.

REST API operations

The Azure SDK for .NET contains libraries that build on top of the Azure REST API, allowing you to interact with REST API operations through familiar .NET paradigms. The client library methods for deleting blobs and restoring deleted blobs use the following REST API operations:

Code samples

Client library resources

See also