public void Handle(AddAttachmentCommand message)
{
if (!_database.IsOpen)
{
throw new DatabaseClosedException();
}
if (message.Entry.Attachments.ContainsKey(message.AttachmentName))
{
throw new ArgumentException("AttachmentAlreadyExists", nameof(message.AttachmentName));
}
_database.AddAttachment(message.Entry.Id, message.AttachmentName, message.AttachmentContent);
message.Entry.Attachments.Add(message.AttachmentName, message.AttachmentContent);
}