原文:
asp.net学习之扩展GridView
1.扩展BoundField
Code
namespace myControls
{
// 自定义GridView的Field字段，该字段能够在显示模式下
// 显示多行文本，在编辑模式下显示多行输入框
public class LongTextField: BoundField // 继承BoundField
{
private Unit _width = new Unit("250px");
private Unit _height = new Unit("60px");
// LongTextField有两个属性，分别是Widht和Height.
public Unit Width {
get { return _width; }
set { _width = value; }
}
public Unit Height {
get { return _height; }
set { _height = value; }
}
// InitializeDataCell 方法是一种帮助器方法，用于初始化 BoundField 对象中的单元格
// 扩展 BoundField 类时，可以重写该方法，以执行自定义初始化例程。
protected override void InitializeDataCell(DataControlFieldCell cell, DataControlRowState rowState)
{
// 不处于编辑模式下
if((rowState&DataControlRowState.Edit)==0){
HtmlGenericControl div = new HtmlGenericControl("div"); //创建一个Html中的div控件
div.Attributes["class"] = "longTextField";
//通过HtmlTextWriterStyle设置div控件的样式
div.Style[HtmlTextWriterStyle.Width] = _width.ToString();
div.Style[HtmlTextWriterStyle.Height] = _height.ToString();
div.Style[HtmlTextWriterStyle.Overflow] = "auto";
// div控件的DataBinding事件发生时，调用div_DataBinding函数
div.DataBinding += new EventHandler(div_DataBinding);
cell.Controls.Add(div);
} else {
TextBox txtEdit = new TextBox();
txtEdit.TextMode = TextBoxMode.MultiLine;
txtEdit.Width = _width;
txtEdit.Height = _height;
// txtEdit的DataBinding事件发生时，调用txtEdit_DataBinding函数
txtEdit.DataBinding += new EventHandler(txtEdit_DataBinding);
cell.Controls.Add(txtEdit);
}
}
void div_DataBinding(object sender,EventArgs e)
{
HtmlGenericControl div = (HtmlGenericControl)sender; // 取得控件
object value = this.GetValue(div.NamingContainer); // Get the field value;
div.InnerText = this.FormatDataValue(value, this.HtmlEncode); // Assign the formatted value
}
void txtEdit_DataBinding(object sender,EventArgs e)
{
TextBox txtEdit = (TextBox)sender;
Object value = this.GetValue(txtEdit.NamingContainer); // Get the field value
txtEdit.Text = this.FormatDataValue(value, this.HtmlEncode);
}
}
}
Code
<%@ Register TagPrefix="custom" Namespace="myControls" %> <!-- 引入LongTextField类型 -->
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="Id" DataSourceID="SqlDataSource1">
<Columns>
<asp:BoundField DataField="Id" HeaderText="Id" InsertVisible="False" ReadOnly="True" SortExpression="Id" />
<asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" />
<asp:BoundField DataField="Director" HeaderText="Director" SortExpression="Director" />
<custom:LongTextField DataField="Description" Width="300px" height="60px" HeaderText="Movie Description" />
</Columns>
</asp:GridView>
2.扩展ButtonField
Code
public class DeleteButtonField : ButtonField
{
private string _confirmMessage = "确认要删除吗?";
public string ConfirmMessage
{
get { return _confirmMessage; }
set { _confirmMessage = value; }
}
// 默认情况下，作为删除按钮，按钮上显示删除字样
public DeleteButtonField()
{
this.CommandName = "Delete";
this.Text = "删除";
}
public override void InitializeCell(DataControlFieldCell cell, DataControlCellType cellType, DataControlRowState rowState, int rowIndex)
{
base.InitializeCell(cell, cellType, rowState, rowIndex);
if(cellType==DataControlCellType.DataCell) //如果是数据Cell
{
WebControl button = (WebControl)cell.Controls[0];
button.Attributes["onclick"] = String.Format("return confirm('{0}');", _confirmMessage);
}
}
}
本节讨论如何从现有的控件，进而扩展成强大的，更定制的GridView控件
1.扩展BoundField
默认的BoundField不能显示多文本，文字一多，就会扩大整个Table的Height值，解决这个问题的方法可以通过TemplateField加入Div控件来解决，但是，也可以从BoundField类上进行扩展，加入一点特有的功能，让他能够显示多文本
例1: 创建长文本字段
===App_code\myControls.cs===
Code
namespace myControls
{
// 自定义GridView的Field字段，该字段能够在显示模式下
// 显示多行文本，在编辑模式下显示多行输入框
public class LongTextField: BoundField // 继承BoundField
{
private Unit _width = new Unit("250px");
private Unit _height = new Unit("60px");
// LongTextField有两个属性，分别是Widht和Height.
public Unit Width {
get { return _width; }
set { _width = value; }
}
public Unit Height {
get { return _height; }
set { _height = value; }
}
// InitializeDataCell 方法是一种帮助器方法，用于初始化 BoundField 对象中的单元格
// 扩展 BoundField 类时，可以重写该方法，以执行自定义初始化例程。
protected override void InitializeDataCell(DataControlFieldCell cell, DataControlRowState rowState)
{
// 不处于编辑模式下
if((rowState&DataControlRowState.Edit)==0){
HtmlGenericControl div = new HtmlGenericControl("div"); //创建一个Html中的div控件
div.Attributes["class"] = "longTextField";
//通过HtmlTextWriterStyle设置div控件的样式
div.Style[HtmlTextWriterStyle.Width] = _width.ToString();
div.Style[HtmlTextWriterStyle.Height] = _height.ToString();
div.Style[HtmlTextWriterStyle.Overflow] = "auto";
// div控件的DataBinding事件发生时，调用div_DataBinding函数
div.DataBinding += new EventHandler(div_DataBinding);
cell.Controls.Add(div);
} else {
TextBox txtEdit = new TextBox();
txtEdit.TextMode = TextBoxMode.MultiLine;
txtEdit.Width = _width;
txtEdit.Height = _height;
// txtEdit的DataBinding事件发生时，调用txtEdit_DataBinding函数
txtEdit.DataBinding += new EventHandler(txtEdit_DataBinding);
cell.Controls.Add(txtEdit);
}
}
void div_DataBinding(object sender,EventArgs e)
{
HtmlGenericControl div = (HtmlGenericControl)sender; // 取得控件
object value = this.GetValue(div.NamingContainer); // Get the field value;
div.InnerText = this.FormatDataValue(value, this.HtmlEncode); // Assign the formatted value
}
void txtEdit_DataBinding(object sender,EventArgs e)
{
TextBox txtEdit = (TextBox)sender;
Object value = this.GetValue(txtEdit.NamingContainer); // Get the field value
txtEdit.Text = this.FormatDataValue(value, this.HtmlEncode);
}
}
}
===custer_list.aspx===
Code
<%@ Register TagPrefix="custom" Namespace="myControls" %> <!-- 引入LongTextField类型 -->
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="Id" DataSourceID="SqlDataSource1">
<Columns>
<asp:BoundField DataField="Id" HeaderText="Id" InsertVisible="False" ReadOnly="True" SortExpression="Id" />
<asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" />
<asp:BoundField DataField="Director" HeaderText="Director" SortExpression="Director" />
<custom:LongTextField DataField="Description" Width="300px" height="60px" HeaderText="Movie Description" />
</Columns>
</asp:GridView>
2.扩展ButtonField
扩充的ButtonField能够具有警告作用，即在点击时能够弹出确认消息。
例2：扩展ButtonField字段
Code
public class DeleteButtonField : ButtonField
{
private string _confirmMessage = "确认要删除吗?";
public string ConfirmMessage
{
get { return _confirmMessage; }
set { _confirmMessage = value; }
}
// 默认情况下，作为删除按钮，按钮上显示删除字样
public DeleteButtonField()
{
this.CommandName = "Delete";
this.Text = "删除";
}
public override void InitializeCell(DataControlFieldCell cell, DataControlCellType cellType, DataControlRowState rowState, int rowIndex)
{
base.InitializeCell(cell, cellType, rowState, rowIndex);
if(cellType==DataControlCellType.DataCell) //如果是数据Cell
{
WebControl button = (WebControl)cell.Controls[0];
button.Attributes["onclick"] = String.Format("return confirm('{0}');", _confirmMessage);
}
}
}
3.待续…
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