递归获取当前父节点下的所有子集

/// <summary>
/// 获取当前父节点下的所有子集
/// </summary>
/// <param name="parent_id"></param>
/// <param name="allFolderList"></param>
/// <returns></returns>
private List<MyManageFolderInfoResponse> GetChildFolder(string parent_id, List<MyManageFolderInfoResponse> allFolderList)
{
var query = from a in allFolderList
where a.parent_id == parent_id
select a;
return query.ToList().Concat(query.ToList().SelectMany(t => GetChildFolder(t.b_id, allFolderList))).ToList();

}

/// <summary>
/// 我管理的文件夹
/// </summary>
public class MyManageFolderInfoResponse
{
public string parent_id { get; set; }
/// <summary>
/// 级数
/// </summary>
public int step_number { get; set; } = 1;

public string b_id { get; set; }
/// <summary>
/// 文件夹名称
/// </summary>
public string folder_name { get; set; }
/// <summary>
/// 文件夹类型，1：常规文件夹，2：任务文件夹
/// </summary>
public int folder_type { get; set; } = 1;
/// <summary>
/// 公开/不公开，1：不公开，2：对所有教师公开，3：对部分教师公开
/// </summary>
public int is_public { get; set; } = 1;
/// <summary>
/// 公开教师ID
/// </summary>

public string public_user_ids { get; set; }

/// <summary>
/// 管理者教师ID
/// </summary>

public string manage_user_ids { get; set; }
/// <summary>
/// 上传教师ID(任务文件夹)
/// </summary>

public string teacher_user_ids { get; set; }
/// <summary>
/// 文档数量
/// </summary>
public int file_count { get; set; } = 0;

/// <summary>
/// 创建人
/// </summary>
public string create_by { get; set; }
/// <summary>
/// 创建时间
/// </summary>
public DateTime create_time { get; set; }

/// <summary>
/// children
/// </summary>
public List<MyManageFolderInfoResponse> children { get; set; }
}