创建列表

Question

一个TreeNode我有一个表，伊利诺伊州作为其叶和samething值为“2” ......通过这样做我得到3“头一个”节点，而不是一个具有下所有的三个节点...

SqlCommand cmd = con.CreateCommand(); 

     comd.CommandText = "SELECT * FROM myTable"; 
     con.Open(); 
     SqlDataReader reader = comd.ExecuteReader(); 
     while (reader.Read()) 
     { 
      City MyData = new City(); 

      MyData.ListA = reader["ListA"].ToString().Trim(); 
      MyData.labelName = reader["labelName"].ToString().Trim(); 
      giveData.Add(MyData); 
     } 

     int count = 1; 

     List<TreeNode> myNode = new List<TreeNode>(); 
     foreach (City MyData in giveData) 
     { 
      // 1st foreach 
       if (MyData.ListA != "1") 
       { 

        TreeNode treeNode = new TreeNode(); 
        treeNode.id = count++; 
        treeNode.name = "Header One"; 
        treeNode.leaf = false; 

        List<TreeNode> Level1 = new List<TreeNode>(); 
        foreach (City labelName in giveData) 
        { 
         if (labelName.ListA == "1") 
         {// 2nd foreach 
          TreeNode node1 = new TreeNode(); 
          node1.id = count++; 
          node1.name = labelName.labelName; 
          node1.leaf = true; 

          Level1.Add(node1); 
         } 
        } 

        treeNode.children = Level1; 
        myNode.Add(treeNode); 
      } 
      else if (MyData.ListA != "2") 
       { 

        TreeNode treeNode = new TreeNode(); 
        treeNode.id = count++; 
        treeNode.name = "Header Two"; 
        treeNode.leaf = false; 

        List<TreeNode> Level1 = new List<TreeNode>(); 
        foreach (City labelName in giveData) 
        { 
         if (labelName.ListA == "2") 
         {// 2nd foreach 
          TreeNode node1 = new TreeNode(); 
          node1.id = count++; 
          node1.name = labelName.labelName; 
          node1.leaf = true; 

          Level1.Add(node1); 
         } 
        } 

        treeNode.children = Level1; 
        myNode.Add(treeNode); 
      } 
     } 
     return JsonConvert.SerializeObject(myNode); 

什么 将是处理此问题的最佳方法

Answer 1

您需要做的是将数据分组在ListA上。

var groups = giveData.GroupBy(state => state.ListA); 

foreach(var group in groups) 
{ 
    //add header to treeview 
    string header = group.Key; 

    foreach(var state in group) 
    { 
     //add this state as a child of the group you just added 
    } 
} 

我也建议创建一个查询，以帮助你映射了ListA数到它的文字表述：

var headerLookup = new Dictionary<string, string>() 
{ 
    {"1", "Header One"}, 
    {"2", "Header Two"}, 
    {"3", "Header Three"} 
}; 

这将允许你做到以下几点：

string headerText = headerLookup[group.Key];