public async Task <string> GetETagAsync(IStorageBlob blob, CancellationToken cancellationToken)
{
try
{
await blob.FetchAttributesAsync(cancellationToken);
}
catch (StorageException exception)
{
// Note that specific exception codes are not available for FetchAttributes, which makes a HEAD request.
if (exception.IsNotFound())
{
// Blob does not exist.
return(null);
}
else if (exception.IsOk())
{
// If the blob type is incorrect (block vs. page) a 200 OK is returned but the SDK throws an
// exception.
return(null);
}
else
{
throw;
}
}
return(blob.Properties.ETag);
}
public static async Task <bool> TryFetchAttributesAsync(this IStorageBlob blob,
CancellationToken cancellationToken)
{
if (blob == null)
{
throw new ArgumentNullException("blob");
}
try
{
await blob.FetchAttributesAsync(cancellationToken);
return(true);
}
catch (StorageException exception)
{
// Remember specific error codes are not available for Fetch (HEAD request).
if (exception.IsNotFound())
{
return(false);
}
else if (exception.IsOk())
{
// If the blob type is incorrect (block vs. page) a 200 OK is returned but the SDK throws an
// exception.
return(false);
}
else
{
throw;
}
}
}
public async Task<string> GetETagAsync(IStorageBlob blob, CancellationToken cancellationToken)
{
try
{
await blob.FetchAttributesAsync(cancellationToken);
}
catch (StorageException exception)
{
// Note that specific exception codes are not available for FetchAttributes, which makes a HEAD request.
if (exception.IsNotFound())
{
// Blob does not exist.
return null;
}
else if (exception.IsOk())
{
// If the blob type is incorrect (block vs. page) a 200 OK is returned but the SDK throws an
// exception.
return null;
}
else
{
throw;
}
}
return blob.Properties.ETag;
}
