關于DataTable中,有設置Expression屬性的列不會激發ColumnChanging事件
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.SqlClient;
namespace test
{
/// <summary>
/// Form4 的摘要描述。
/// </summary>
public class Form4 : System.Windows.Forms.Form
{
private System.Windows.Forms.DataGrid dataGrid1;
private DataSet myDataSet=new DataSet();
/// <summary>
/// 設計工具所需的變數。
/// </summary>
private System.ComponentModel.Container components = null;
public Form4()
{
InitializeComponent();
}
/// <summary>
/// 清除任何使用中的資源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if(components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form 設計工具產生的程式碼
/// <summary>
/// 此為設計工具支援所必須的方法 - 請勿使用程式碼編輯器修改
/// 這個方法的內容。
/// </summary>
private void InitializeComponent()
{
this.dataGrid1 = new System.Windows.Forms.DataGrid();
((System.ComponentModel.ISupportInitialize)(this.dataGrid1)).BeginInit();
this.SuspendLayout();
//
// dataGrid1
//
this.dataGrid1.DataMember = " ";
this.dataGrid1.Dock = System.Windows.Forms.DockStyle.Fill;
this.dataGrid1.HeaderForeColor = System.Drawing.SystemColors.ControlText;
this.dataGrid1.Location = new System.Drawing.Point(0, 0);
this.dataGrid1.Name = "dataGrid1 ";
this.dataGrid1.Size = new System.Drawing.Size(568, 357);
this.dataGrid1.TabIndex = 0;
//
// Form4
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 15);
this.ClientSize = new System.Drawing.Size(568, 357);
this.Controls.Add(this.dataGrid1);
this.Name = "Form4 ";
this.Text = "Form4 ";
this.Load += new System.EventHandler(this.Form4_Load);
((System.ComponentModel.ISupportInitialize)(this.dataGrid1)).EndInit();
this.ResumeLayout(false);
}
#endregion
private void Form4_Load(object sender, System.EventArgs e)
{
using(SqlDataAdapter ada=new SqlDataAdapter( " SELECT *, ' ' as tmp FROM Categories ", "data Source=.;database=Northwind;user id=sa;pwd=; "))
{
ada.Fill(this.myDataSet, "tt ");
this.myDataSet.Tables[0].Columns[ "tmp "].Expression= "iif(CategoryID> 3, 'small ', 'big ') ";
this.myDataSet.Tables[0].Columns.Add( "tmp1 ",typeof(string));
this.myDataSet.Tables[0].Columns.Add( "tmp2 ",typeof(string), "iif(CategoryID> 3, 'small ', 'big ') ");
this.myDataSet.Tables[0].ColumnChanging+=new DataColumnChangeEventHandler(this.DataColumn_ColumnChanging);
this.dataGrid1.DataSource=this.myDataSet.Tables[0];
#region 將增加的tmp2列修改為可讀寫
DataGridTableStyle dgts=new DataGridTableStyle();
dgts.MappingName=this.myDataSet.Tables[0].TableName;
this.dataGrid1.TableStyles.Clear();
this.dataGrid1.TableStyles.Add(dgts);
DataGridColumnStyle dgcs = dgts.GridColumnStyles[ "tmp "];
(dgcs as DataGridTextBoxColumn).ReadOnly=false;
dgcs = dgts.GridColumnStyles[ "tmp2 "];
(dgcs as DataGridTextBoxColumn).ReadOnly=false;
#endregion
}
}
private void DataColumn_ColumnChanging(object sender,System.Data.DataColumnChangeEventArgs e)
{
#region 輸入資料檢測
try
{
if(e.Row[e.Column.ColumnName,(e.Row.RowState==DataRowState.Detached?DataRowVersion.Proposed:(e.Row.RowState==DataRowState.Added?DataRowVersion.Default:DataRowVersion.Original))]!=e.ProposedValue)
{
switch(e.Column.ColumnName.ToLower())
{
case "tmp1 ":
MessageBox.Show(e.Column.ColumnName+ "\r\n\r\n "+e.ProposedValue.ToString());
break;
case "tmp2 ":
MessageBox.Show(e.Column.ColumnName+ "\r\n\r\n "+e.ProposedValue.ToString());
break;
default:
MessageBox.Show(e.Column.ColumnName);
break;
}
}
}
catch(Exception ex)
{
MessageBox.Show(ex.Message, "Error ",MessageBoxButtons.OK,MessageBoxIcon.Error);
}
#endregion
}
}
}
tmp和tmp列有設置Expression屬性.
說明:
1.增加時新行時,會引發有設置Expression屬性的列的DataColukning事件;
2.修改行時,不會引發有設置Expression屬性的列的DataColukning事件.
如何才能在修改有設置Expression屬性列的值時引發DataColumning事件?
[解决办法]
不结贴可不是好孩子呀
