向treeview C＃添加项目时出错 [英] Error while adding items to treeview C#

问题描述

我编写了以下代码来创建树视图：它从sqlCEserver读取数据并生成视图。它在我进入内部while循环之前正常工作以在标题中添加子项。

I have written the following code to create a tree view: it reads data from a sqlCEserver and generates view according. It was working fine before i entered the inner while loop to add sub items in header.

private void ClientTree_Initialized(object sender, EventArgs e)
       {
            string moduleCat = null;
            string Cname = null;
            SqlCeConnection _con = new SqlCeConnection(@"Data Source=C:\ClientDB.sdf");
            _con.Open();
            SqlCeDataReader _reader = null;
            SqlCeDataReader _reader1 = null;
            SqlCeCommand readMod = new SqlCeCommand(@"SELECT DISTINCT ModuleID FROM ClientRecord", _con);

            _reader = readMod.ExecuteReader();
            while(_reader.Read())
            {

                moduleCat = _reader["ModuleID"].ToString();

                treeItem = new TreeViewItem();
                treeItem.Header = moduleCat;

                SqlCeCommand readName = new SqlCeCommand(@"SELECT Cname FROM ClientRecord WHERE (ModuleID = '" + moduleCat + @"')", _con);
                _reader1 = readName.ExecuteReader();
                while (_reader1.Read())
                {
                    Cname = _reader["Cname"].ToString();
                    treeItem.Items.Add(new TreeViewItem() { Header = Cname });
                    ClientTree.Items.Add(treeItem);
                }
            }
        }

它给出了这个例外：

it gave this exception:

System.Windows.Markup.XamlParseException occurred
  HResult=-2146233087
  Message='Initialization of 'System.Windows.Controls.TreeView' threw an exception.' Line number '10' and line position '99'.
  Source=PresentationFramework
  LineNumber=10
  LinePosition=99

第10行是：< br $> b $ b

line number 10 is:

<TreeView x:Name="ClientTree" Height="350.4" Width="164.2" HorizontalAlignment="Left" VerticalAlignment="Top" Initialized="ClientTree_Initialized" />

推荐答案

我认为问题在于你的第二个while循环中的代码。请注意，您正在_reader中查找Cname字段，该字段不在此阅读器中...

I think the issue is with the code in your second while loop. Notice that you are looking in the _reader for the 'Cname' field which isn't in this reader...

while (_reader1.Read())
{
    Cname = _reader["Cname"].ToString();
    treeItem.Items.Add(new TreeViewItem() { Header = Cname });
    ClientTree.Items.Add(treeItem);
}

...我很确定你想要在你的第二个while循环中调用第二个阅读器（_reader1）。像这样...

...I am pretty sure you want to call the second reader (_reader1) in your second while loop. Like so...

while (_reader1.Read())
{
    Cname = _reader1["Cname"].ToString();
    treeItem.Items.Add(new TreeViewItem() { Header = Cname });
    ClientTree.Items.Add(treeItem);
}

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