Extjs treePanel 后台Json的两种构建方法

        public string json = "";
        public string QueryMenuTreeJson(string ParentID, string userId)
        {
            json = "";
            GetResourceTreeJson(ParentID, userId);
            return json;
        }
        public string GetResourceTreeJson(string ParentID, string userId)
        {
            DataTable dt = new DataTable();
            string sql = "select c.Title as 'text',c.ID,case when c.IsLeaf=0 then 'false' else 'true' end as 'leaf',c.Url as 'url'"
            + " from SysUserRole a,SysRoleResource b,SysResource c where a.UserID = " + userId +
              " and a.IsDeleted = 0 and b.IsDeleted = 0 and c.IsDeleted = 0 "
            + " and b.RoleID = a.RoleID and b.ResourceID = c.ID and c.ParentID = " + ParentID + " order by c.ID";
            using (End.DataCore.IDbAction db = End.DataCore.DbSessionFactory.GetDbSession())
            {
                dt = db.ExecuteQuery(sql);
            }
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                if (dt.Rows[i][2].ToString() != "true")
                {
                    json += "{'text':'" + dt.Rows[i][0] + "'";
                    json += ",'leaf':'false','id':'" + dt.Rows[i][1] + "','children':[";
                    GetResourceTreeJson(dt.Rows[i][1].ToString(), userId);
                    json += "]";
                }
                else
                {
                    json += "{'text':'" + dt.Rows[i][0] + "','leaf':'true','id':'" + dt.Rows[i][1] + "','url':'" + dt.Rows[i][3] + "'";
                }
                json += "},";
            }
            return json;
        }

　　上面的是小白自己的写的一种完全手动拼接的Json数据，希望可以给大家帮助。但是有一定的弊端（每次递归都去查询数据库，还有就是拼接存在一定的安全性因素），后来小白就改成了用类封装的方式，然后通过返回List的类型的数据，然后通过json类的帮助，自动将list转换成json数据，而且我上面的代码是每进行一次的递归操作，就去数据库中查询一次，这样涉及到数据库的开关，因此，小白将所有的相关的数据都一次性查了出来，然后将dt 作为参数，递归传入方法中，详情可以参照代码。

List<Model.ResourceNode> NodeList = null;

        public List<Model.ResourceNode> GetMenuTreeStore(string userId)
        {
            NodeList = new List<Model.ResourceNode>();
            DataTable dt = new DataTable();
            List<End.DataCore.ModelBase.Column> list = new List<End.DataCore.ModelBase.Column>();
            list.Add(new End.DataCore.ModelBase.Column("@userID", (userId)));
            string sql = "select c.Title as 'text',c.ID,case when c.IsLeaf=0 then 'false' else 'true' end as 'leaf',c.Url as 'url',c.ParentID as 'parentId'  "
            + " from SysUserRole a,SysRoleResource b,SysResource c where  userId = @userID" 
            + " and a.IsDeleted = 0 and b.IsDeleted = 0 and c.IsDeleted = 0 "
            + " and b.RoleID = a.RoleID and b.ResourceID = c.ID order by c.ID";
            using (End.DataCore.IDbAction db = End.DataCore.DbSessionFactory.GetDbSession())
            {
                dt = db.ExecuteQuery(sql, list);
            }
            string sqlSelect = "parentId = 0";
            DataTable newTable = dt.Copy();
            newTable.Rows.Clear();
            DataRow[] rows = dt.Select(sqlSelect);
            for (int i = 0; i < rows.Length; i++)
            {
                newTable.Rows.Add(rows[i].ItemArray);
            }
            for (int i = 0; i < newTable.Rows.Count; i++)
            {
                ResourceNode childrenNode = new ResourceNode();
                childrenNode.text = newTable.Rows[i][0].ToString();
                childrenNode.leaf = newTable.Rows[i][2].ToString();
                childrenNode.ID = Convert.ToInt32(newTable.Rows[i][1]);
                childrenNode.url = newTable.Rows[i][3].ToString();
                GetResourceTreeList(dt, childrenNode);
                NodeList.Add(childrenNode);
            }
            return NodeList;
        }下面的为递归法调用的GetResourceTreeList方法，他的优点就在于不需要每次递归都去查询数据库，他是对整个的表格进行过滤筛选，代码如下：

public void GetResourceTreeList(DataTable dt, Model.MenuNode node)
{
string sqlSelect = "parentId = " + node.ID;
DataTable newTable = dt.Copy();
newTable.Rows.Clear();
DataRow[] rows = dt.Select(sqlSelect);
for (int i = 0; i < rows.Length; i++)
{
newTable.Rows.Add(rows[i].ItemArray);
}
node.children = new List<MenuNode>();
for (int i = 0; i < newTable.Rows.Count; i++)
{
if (newTable.Rows[i][2].ToString() != "true")
{
MenuNode resourceNode = new MenuNode();
resourceNode.text = newTable.Rows[i][0].ToString();
resourceNode.leaf = newTable.Rows[i][2].ToString();
resourceNode.ID = Convert.ToInt32(newTable.Rows[i][1]);
GetResourceTreeList(dt, resourceNode);
node.children.Add(resourceNode);
}
else
{
MenuNode childrenNode = new MenuNode();
childrenNode.text = newTable.Rows[i][0].ToString();
childrenNode.leaf = newTable.Rows[i][2].ToString();
childrenNode.ID = Convert.ToInt32(newTable.Rows[i][1]);
childrenNode.url = newTable.Rows[i][3].ToString();
node.children.Add(childrenNode);
}
}

}下面的是代码是类的声明。

　　

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace OA.Core.Model
{
    public class ResourceNode
    {
        private int Id;
        private string Text;
        private string Leaf;
        private string Url;
        private List<ResourceNode> Children;

        public Int32 ID
        {
            get
            {
                return this.Id;
            }
            set
            {
                this.Id = value;
            }
        }

        public string text
        {
            get
            {
                return this.Text;
            }
            set
            {
                this.Text = value;
            }
        }

        public string leaf
        {
            get
            {
                return this.Leaf;
            }
            set
            {
                this.Leaf = value;
            }
        }

        public string url
        {
            get
            {
                return this.Url;
            }
            set
            {
                this.Url = value;
            }
        }

        public List<ResourceNode> children
        {
            get
            {
                return this.Children;
            }
            set
            {
                this.Children = value;
            }
        }
    }
}

在递归方法都写好的同时，小白还遇到一个问题，就是直接将获取List转换成的数据传入前台，然后直接调用的时候，发现一个问题，就是数据结构为:Children Text这种形式，然后最终发现竟然在界面上不显示，然后小白通过喊救兵，在@bom wu的引导下，发现Treepanel对数据都严格区分大小写，然后我后来又将类改成上面的样子，这一点大家要注意，而且，如果要加上treePanel Node不是默认的属性，例如Url，可以在Store里面加上Model或者加上fields属性，来解析。　　

最后，衷心的希望小白的这篇文章能对大家在接触树的时候有帮助！谢谢大家的阅读。