左右值无限级分类 MVC + EntityFramework 的简单实现

　　在度娘上查了大半个月的资料，最后发现每个网友分享的文章都有一定的错误（PS：大家是故意的么？）。最后是在看了一个ASP版本后知道了大概流程；看了一个存储过程实现的文章后知道了大概需要的功能；看了一个SQL语句看到了比较直观的实现；看了一个php示例后才知道最复杂的一个功能的实现。每篇文章都是网友们自己正在使用或已经测试通过的，但都很巧，恰好关键地方就有点出错，不过还是感谢这些资料了，不然我也搞不出来。

　　因为查了很久的资料，基本上没有可用的，所以一直不敢直接写到项目的DAL里面，就直接在控制器里面写方法进行了调试，暂时没考虑什么意外情况和效率问题，毕竟出现上述问题的前提条件是你这个功能要实现吧，呵呵，下面直接上代码（PS：有点丑，见谅）。

 　　　　　　//数据初始化，反正失败了几十次，所以就在前面写了段初始化的代码，经常用到
             cManager.DelByCondition(c => c.Id != );
             Models.CmsMiee_Article_Category cate1 = new Models.CmsMiee_Article_Category() { Name = "商品", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate2 = new Models.CmsMiee_Article_Category() { Name = "食品", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate3 = new Models.CmsMiee_Article_Category() { Name = "肉类", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate4 = new Models.CmsMiee_Article_Category() { Name = "猪肉", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate5 = new Models.CmsMiee_Article_Category() { Name = "蔬菜类", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate6 = new Models.CmsMiee_Article_Category() { Name = "白菜", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate7 = new Models.CmsMiee_Article_Category() { Name = "电器", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate8 = new Models.CmsMiee_Article_Category() { Name = "电视机", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             Models.CmsMiee_Article_Category cate9 = new Models.CmsMiee_Article_Category() { Name = "电冰箱", ClassLeftNum = , ClassRightNum = , ListSkin = "test", ContentSkin = "text" };
             cManager.Add(cate1);
             cManager.Add(cate2);
             cManager.Add(cate3);
             cManager.Add(cate4);
             cManager.Add(cate5);
             cManager.Add(cate6);
             cManager.Add(cate7);
             cManager.Add(cate8);
             cManager.Add(cate9);
             return new MvcHtmlString("OK");

 　　　　　　　//整体数据，后面涉及一些基本操作所调用的实体有些就是用的这个
             long nodeId = ;
             Models.CmsMiee_Article_Category cate = cManager.GetById(nodeId);
             //一、计算A节点的子节点数。 $num = ($AR - $AL -1)/2;
             return Json((cate.ClassRightNum - cate.ClassLeftNum - ) / , JsonRequestBehavior.AllowGet);

 　　　　　　　//二、查找A节点的所有子节点。
             select * from tree where L > $AL and R < $AR order by L asc;
             List<Models.CmsMiee_Article_Category> childCate = cManager.GetListByCondition(c => c.ClassLeftNum > cate.ClassLeftNum && c.ClassRightNum < cate.ClassRightNum, c => c.ClassLeftNum);
             return Json(childCate, JsonRequestBehavior.AllowGet);

 　　　　　　　//三、查找A节点的所有父节点。
             select * from tree where L < $AL and R > $AR order by L desc;
             List<Models.CmsMiee_Article_Category> parentCate = cManager.GetListByCondition(c => c.ClassLeftNum < cate.ClassLeftNum && c.ClassRightNum > cate.ClassRightNum, c => c.Id);
             string r1 = "";
             foreach (Models.CmsMiee_Article_Category c in parentCate)
             {
                 r1 += "," + c.Name;
             }
             return new MvcHtmlString(r1);

 　　　　　　　//四、在A节点下增加子节点B，B作为最后一个子节点。
             update tree set L = L +  where L >= $AR;
             update tree set R = R +  where R >= $AR;
             insert into tree (name, L, R) values('B', $AR-, $AR);
             List<Models.CmsMiee_Article_Category> update1 = cManager.GetListByCondition(c => c.ClassLeftNum >= cate.ClassRightNum, c => c.ClassLeftNum);
             List<Models.CmsMiee_Article_Category> update2 = cManager.GetListByCondition(c => c.ClassRightNum >= cate.ClassRightNum, c => c.ClassLeftNum);
             foreach (Models.CmsMiee_Article_Category c in update1)
             {
                 c.ClassLeftNum += ;
                 cManager.Modify(c, "ClassLeftNum");
             }
             foreach (Models.CmsMiee_Article_Category c in update2)
             {
                 c.ClassRightNum += ;
                 cManager.Modify(c, "ClassRightNum");
             }
             Models.CmsMiee_Article_Category newClass = new Models.CmsMiee_Article_Category() { Name = "北极企鹅", ClassLeftNum = cate.ClassRightNum - , ClassRightNum = cate.ClassRightNum - , ListSkin = "test", ContentSkin = "text" };
             cManager.Add(newClass);
             return Json("OK", JsonRequestBehavior.AllowGet);

 　　　　　　　//五、输出节点下的所有子节点，并提供层级等信息以便生成节点树
             List<Models.CmsMiee_Article_Category> childCate = cManager.GetListByCondition(c => c.ClassLeftNum >= cate.ClassLeftNum && c.ClassRightNum <= cate.ClassRightNum, c => c.ClassRightNum);
             List<Models.CmsMiee_Article_Category_Layer> cateList = new List<Models.CmsMiee_Article_Category_Layer>();
             foreach (Models.CmsMiee_Article_Category c in childCate)
             {
                 Models.CmsMiee_Article_Category_Layer newCate = new Models.CmsMiee_Article_Category_Layer();
                 newCate.Id = c.Id;
                 newCate.Name = c.Name;
                 newCate.ClassLeftNum = c.ClassLeftNum;
                 newCate.ClassRightNum = c.ClassRightNum;
                 newCate.ListSkin = c.ListSkin;
                 newCate.ContentSkin = c.ContentSkin;
                 newCate.AddTime = c.AddTime;
                 newCate.DelTime = c.DelTime;
                 newCate.IsDeleted = c.IsDeleted;
                 newCate.Layer = cManager.GetListByCondition(c1 => c1.ClassLeftNum <= newCate.ClassLeftNum && c1.ClassRightNum >= newCate.ClassRightNum, c1 => c.ClassLeftNum).Count;
                 cateList.Add(newCate);
             }
             //拼接节点树
             string tree = "";
             foreach (Models.CmsMiee_Article_Category_Layer cl in cateList)
             {
                 string tab = "";
                 //根据层级生成制表符
                 for (int index = ; index < cl.Layer; index++) { tab += "  "; }
                 tree += tab + cl.Name + " - 层级：" + cl.Layer + "\n";
             }
             MvcHtmlString result = new MvcHtmlString("<pre>" + tree + "</pre>");
             return result;

 　　　　　　　//六、删除A节点。先要计出该节点及其所有子节点所占的左右值空间，将这些节点删掉，然后更新其它节点的左右值。
             $num = $AR - $AL + ;
             delete from tree where L >= $AL and R <= $AR;
             update tree set R = R - $num where R > $AR;
             update tree set  = L - $num where L > $AR;
             long cateLAR = cate.ClassRightNum - cate.ClassLeftNum + ;
             cManager.DelByCondition(c => c.ClassLeftNum >= cate.ClassLeftNum && c.ClassRightNum <= cate.ClassRightNum);
             List<Models.CmsMiee_Article_Category> update1 = cManager.GetListByCondition(c => c.ClassRightNum > cate.ClassRightNum, c => c.ClassRightNum);
             List<Models.CmsMiee_Article_Category> update2 = cManager.GetListByCondition(c => c.ClassLeftNum > cate.ClassRightNum, c => c.ClassRightNum);
             foreach (Models.CmsMiee_Article_Category c in update1)
             {
                 c.ClassRightNum -= cateLAR;
                 cManager.Modify(c, "ClassRightNum");
             }
             foreach (Models.CmsMiee_Article_Category c in update2)
             {
                 c.ClassLeftNum -= cateLAR;
                 cManager.Modify(c, "ClassLeftNum");
             }
             MvcHtmlString result = new MvcHtmlString("OK");
             return result;

 　　　　　　　//七、分类的父级修改
             //1.如果目标节点的ClassRightNum小于当前节点的ClassRightNum；并且目标节点的ClassLeftNum大于当前节点的ClassLeftNum，则返回第一个错误：
             long selfCategoryId = ;   //要移动的节点
             long newCategoryId = ;    //目标节点
             Models.CmsMiee_Article_Category selfCategory = cManager.GetById(selfCategoryId);
             Models.CmsMiee_Article_Category newCategory = cManager.GetById(newCategoryId);
             if (selfCategory == null) return new MvcHtmlString("当前所操作的分类不存在！");
             if (newCategory == null) return new MvcHtmlString("您选择的新分类不存在！");
             long selfLeft = selfCategory.ClassLeftNum;
             long selfRight = selfCategory.ClassRightNum;
             long value = selfRight - selfLeft;
             //取得该分类下面的所有分类，包括自身
             List<Models.CmsMiee_Article_Category> selfCategories = cManager.GetListByCondition(c => c.ClassLeftNum >= selfLeft && c.ClassRightNum <= selfRight, c => c.Id);
             //将所有分类的ID写入数组以便更新左右值
             long[] selfCategoryIDS = new long[selfCategories.Count];
             for (int index = ; index < selfCategoryIDS.Length; index++)
             {
                 selfCategoryIDS[index] = Convert.ToInt32(selfCategories[index].Id);
             }
             //将所有子类及自身的id组成字符串，逗号分隔
             string inIDS = string.Join(",", selfCategoryIDS);
             long parentLeft = newCategory.ClassLeftNum;
             long parentRight = newCategory.ClassRightNum;
             //读取新父级分类的所有父级分类及其层级
             List<Models.CmsMiee_Article_Category> newParentCate1 = cManager.GetListByCondition(c => c.ClassLeftNum < newCategory.ClassLeftNum && c.ClassRightNum > newCategory.ClassRightNum, c => c.Id);
             List<Models.CmsMiee_Article_Category_Layer> newParentCate = new List<Models.CmsMiee_Article_Category_Layer>();
             foreach (Models.CmsMiee_Article_Category c in newParentCate1)
             {
                 Models.CmsMiee_Article_Category_Layer newCate = new Models.CmsMiee_Article_Category_Layer();
                 newCate.Id = c.Id;
                 newCate.Name = c.Name;
                 newCate.ClassLeftNum = c.ClassLeftNum;
                 newCate.ClassRightNum = c.ClassRightNum;
                 newCate.ListSkin = c.ListSkin;
                 newCate.ContentSkin = c.ContentSkin;
                 newCate.AddTime = c.AddTime;
                 newCate.DelTime = c.DelTime;
                 newCate.IsDeleted = c.IsDeleted;
                 newCate.Layer = cManager.GetListByCondition(c1 => c1.ClassLeftNum <= newCate.ClassLeftNum && c1.ClassRightNum >= newCate.ClassRightNum, c1 => c.ClassLeftNum).Count;
                 newParentCate.Add(newCate);
             }
             //判断是前移还是后移，并更新数据库
             if (parentRight > selfRight)
             {
                 //后移
                 //更新左边值
                 //update CmsMiee_Article_Category set ClassLeftNum=ClassLeftNum-value-1 where ClassLeftNum>selfRight and ClassRightNum<=parentRight
                 List<Models.CmsMiee_Article_Category> tempCategories = cManager.GetListByCondition(c => c.ClassLeftNum > selfRight && c.ClassRightNum <= parentRight, c => c.Id);
                 foreach (Models.CmsMiee_Article_Category c in tempCategories)
                 {
                     c.ClassLeftNum = c.ClassLeftNum - value - ;
                     cManager.Modify(c, "ClassLeftNum");
                 }
                 //更新新父类的父类的左边值
                 foreach (Models.CmsMiee_Article_Category_Layer c in newParentCate)
                 {
                     if (c.Layer == ) continue;
                     c.ClassLeftNum = c.ClassLeftNum - value - ;
                     //转换为不带层级的分类后更新到数据库中
                     Models.CmsMiee_Article_Category result = cManager.GetById(c.Id);
                     result.ClassLeftNum = c.ClassLeftNum;
                     cManager.Modify(result, "ClassLeftNum");
                 }
                 //update CmsMiee_Article_Category set ClassRightNum=ClassRightNum-value-1 where ClassRightNum>selfRight and ClassRightNum<parentRight
                 //更新右边值
                 tempCategories = cManager.GetListByCondition(c => c.ClassRightNum > selfRight && c.ClassRightNum < parentRight, c => c.Id);
                 foreach (Models.CmsMiee_Article_Category c in tempCategories)
                 {
                     c.ClassRightNum = c.ClassRightNum - value - ;
                     cManager.Modify(c, "ClassRightNum");
                 }
                 long tempValue = parentRight - selfRight - ;
                 tempCategories = cManager.GetListByCondition(c => selfCategoryIDS.Contains(c.Id), c => c.Id);
                 //update CmsMiee_Article_Category set ClassLeftNum=ClassLeftNum+tempValue,ClassRightNum=ClassRightNum+tempValue where Id in(selfCategoryIDS)
                 foreach (Models.CmsMiee_Article_Category c in tempCategories)
                 {
                     c.ClassLeftNum = c.ClassLeftNum + tempValue;
                     c.ClassRightNum = c.ClassRightNum + tempValue;
                     cManager.Modify(c, "ClassLeftNum", "ClassRightNum");
                 }
             }
             else
             {
                 //前移
                 List<Models.CmsMiee_Article_Category> tempCategories = cManager.GetListByCondition(c => c.ClassLeftNum > parentRight && c.ClassLeftNum < selfLeft, c => c.Id);
                 //更新左边值
                 foreach (Models.CmsMiee_Article_Category c in tempCategories)
                 {
                     c.ClassLeftNum = c.ClassLeftNum + value + ;
                     cManager.Modify(c, "ClassLeftNum");
                 }
                 //更新右边值
                 tempCategories = cManager.GetListByCondition(c => c.ClassRightNum >= parentRight && c.ClassRightNum < selfLeft, c => c.Id);
                 foreach (Models.CmsMiee_Article_Category c in tempCategories)
                 {
                     c.ClassRightNum = c.ClassRightNum + value + ;
                     cManager.Modify(c, "ClassRightNum");
                 }
                 long tempValue = selfLeft - parentRight;
                 tempCategories = cManager.GetListByCondition(c => selfCategoryIDS.Contains(c.Id), c => c.Id);
                 foreach (Models.CmsMiee_Article_Category c in tempCategories)
                 {
                     c.ClassLeftNum = c.ClassLeftNum - tempValue;
                     c.ClassRightNum = c.ClassRightNum - tempValue;
                     cManager.Modify(c, "ClassLeftNum", "ClassRightNum");
                 }
             }
             return new MvcHtmlString("操作完成！");

　　估计是特别乱了，昨天整理了好久，总算是放到DAL里面去了，最后一个修改的功能，步骤稍微有点繁琐。为以防万一，我用的是事务，反正很简单，SaveChange你懂的》。。。

　　变量里面用到的cManager对象是BLL中管理分类用的类，没有什么特别，只是继承了父类的增删改查功能。

　　这段代码只是我测试、学习的时候用到的，后来改动了很多地方，不过关于数据库操作和无限级分类这一块，基本上没什么改动了。没这么无私，所以懒得整理了（PS：我要是像大神们那样整理，估计代码中也会“恰巧”出现一点点关键地方的错误了，呵呵）。所以需要用的朋友可以自行整理一下。