Lambda 递归获取所有子节点

public class Organization
    {
        public string OID { get; set; }
        public string FathOID { get; set; }
        public string OrganizationDesc { get; set; }
        
    }

public static List<Organization> GetWithChildrenList(List<Organization> list, string organizationID)
        {
            Organization curr = list.Where(x => x.OID == organizationID).FirstOrDefault();
            List<Organization> childrenList = new List<Organization>();
            if (curr != null)
            {
                childrenList = GetChildrenList(list, organizationID);
                
            }
            childrenList.Add(curr);
            return childrenList;
        }

        public static List<Organization> GetChildrenList(List<Organization> list, string organizationID)
        {

            var query = list.Where(x => x.FathOID == organizationID).ToList();
            return query.Concat(query.SelectMany(t => GetChildrenList(list, t.OID))).ToList();

        }

//测试代码

List<Organization> organizations = new List<Organization>();
            Organization ot1 = new Organization(){ OID="001",FathOID="0",OrganizationDesc="公司1"};
            Organization ot2 = new Organization() { OID = "002", FathOID = "001", OrganizationDesc = "财务部" };
            Organization ot3 = new Organization() { OID = "003", FathOID = "001", OrganizationDesc = "仓储部" };
            Organization ot4 = new Organization() { OID = "002001", FathOID = "002", OrganizationDesc = "财务小组21" };
            Organization ot5 = new Organization() { OID = "002001001", FathOID = "002001", OrganizationDesc = "财务小组21财务小组21" };

            organizations.Add(ot1);
            organizations.Add(ot2);
            organizations.Add(ot3);
            organizations.Add(ot4);
            organizations.Add(ot5);

            List<Organization> tt = GetWithChildrenList(organizations, "002");