/// <summary>
/// 获取根节点
/// </summary>
/// <returns></returns>
public async Task <Node> GetRootNodeAsync()
{
var node = await Task.Run(() => Nodes.Find(1));
if (node == null)
{
node = new Node()
{
LastWriteTime = DateTime.Now
};
await Nodes.AddAsync(node);
await SaveChangesAsync();
}
return(node);
}