如何在linq中从父ID中获取所有子元素和孙元素

public class Node
{
    public int Id { get; set; }
    public int ParentId { get; set; }
    // 其他属性...
}

public static IEnumerable<Node> GetAllDescendants(IEnumerable<Node> nodes, int parentId)
{
    var descendants = nodes.Where(node => node.ParentId == parentId);
    foreach (var descendant in descendants)
    {
        yield return descendant;
        foreach (var child in GetAllDescendants(nodes, descendant.Id))
        {
            yield return child;
        }
    }
}

// 使用示例
var nodes = new List<Node>
{
    new Node { Id = 1, ParentId = 0 },
    new Node { Id = 2, ParentId = 1 },
    new Node { Id = 3, ParentId = 1 },
    new Node { Id = 4, ParentId = 2 },
    new Node { Id = 5, ParentId = 2 },
    new Node { Id = 6, ParentId = 3 },
    new Node { Id = 7, ParentId = 3 },
};

var parentId = 1;
var descendants = GetAllDescendants(nodes, parentId);
foreach (var descendant in descendants)
{
    Console.WriteLine(descendant.Id);
}