Azure CloudBlockBlob.DeleteIfExists() - Does false always mean the blob doesn't exist?

Question

I know that CloudBlockBlob.DeleteIfExists() returns true if the blob exists and false when it does not.

However I'm curious the know what happens if the blob does exist, but something goes wrong in Azure which causes the file deletion to not occur (I can't find any documentation on that behavior).

My concern is that it will return false instead of throwing some kind of exception, so I'll believe the blob is deleted, when it's actually still there.

In short, if I get a value of false back, does it always mean that the blob didn't exist, no deletion was necessary, and I'll get some kind of exception if something goes wrong on Azure's end?

Thanks.

Answer 1

Looking at the source code for this method here, you will get true if the blob is deleted, false if the blob (or blob container) doesn't exist. In all other circumstances (say the blob is leased and thus can't be deleted), an exception will be raised. Here's the relevant code:

    public virtual bool DeleteIfExists(DeleteSnapshotsOption deleteSnapshotsOption = DeleteSnapshotsOption.None, AccessCondition accessCondition = null, BlobRequestOptions options = null, OperationContext operationContext = null)
    {
        BlobRequestOptions modifiedOptions = BlobRequestOptions.ApplyDefaults(options, BlobType.Unspecified, this.ServiceClient);
        operationContext = operationContext ?? new OperationContext();

        try
        {
            this.Delete(deleteSnapshotsOption, accessCondition, modifiedOptions, operationContext);
            return true;
        }
        catch (StorageException e)
        {
            if (e.RequestInformation.HttpStatusCode == (int)HttpStatusCode.NotFound)
            {
                if ((e.RequestInformation.ExtendedErrorInformation == null) ||
                    (e.RequestInformation.ExtendedErrorInformation.ErrorCode == BlobErrorCodeStrings.BlobNotFound) ||
                    (e.RequestInformation.ExtendedErrorInformation.ErrorCode == BlobErrorCodeStrings.ContainerNotFound))
                {
                    return false;
                }
                else
                {
                    throw;
                }
            }
            else
            {
                throw;
            }
        }
    }