WinForm 递归生成部门树

利用 ADO.NET 从数据库获取部门数据，然后按深度优先依次生成部门树结构。

//窗体加载事件
private void Form_Load(object sender, EventArgs e)
{
    TreeNode root;

    //先设置根节点为起始位置
    root = treeView1.Nodes[0];

    //然后获取所有的节点数据，并缓存，方便后面筛选子节点
    DataSet ds = SQLHelper.Query(SQLHelper._connstr, "SELECT deptId,parentId,deptCode,deptName,level FROM Department");
    List<DeptDto> all = ExtensionMethod.ConvertToModel<DeptDto>(ds.Tables[0]);

    //递归生成树
    LoadTreeRecursive(all, root, "0");
    
    treeView1.ExpandAll();
}

//递归生成树结构
private void LoadTreeRecursive(List<TypeDetail> dataList, TreeNode curNode, string curId)
{
    List<DeptDto> children = dataList.Where(d => d.fore_id.Trim() == curId).ToList();

    foreach (TypeDetail type in children) //当children为空时会自动停止执行
    {
        TreeNode node;
        node = new TreeNode(type.type_name);
        node.ImageIndex = 1;
        node.SelectedImageIndex = 1;
        node.Tag = type;

        //按深度优先，逐层添加子节点
        curNode.Nodes.Add(node);

        //搜索下一层
        LoadTreeRecursive(dataList, node, ((TypeDetail)node.Tag).type_id);
    }
}

//DataTable 转 List<T> 的扩展方法
public static List<T> ConvertToModel<T>(this DataTable table) where T : new()
{
    var list = new List<T>();
    PropertyInfo[] propertys = typeof(T).GetProperties();

    foreach (DataRow row in table.Rows)
    {
        T model = Activator.CreateInstance<T>();
        foreach (PropertyInfo pi in propertys)
        {
            var tempName = pi.Name;
            if (!table.Columns.Contains(tempName)) continue;
            if (!pi.CanWrite) continue;
            object value = Convert.ToString(row[tempName]);
            if (value != DBNull.Value)
            {
                pi.SetValue(model, value, null);
            }
        }

        list.Add(model);
    }
    return list;
}

//表结构对应的实体类
public class DeptDto
{
    public string deptId { get; set; }
    public string parentId { get; set; }
    public string deptCode { get; set; }
    public string deptName { get; set; }
    public string level { get; set; }
}