在GridView中用DataTable，定义模板页，PostBack后TextBox值犹在，但dropDownList值没了，请高手解决......
首先模板类如下
======
public class MyTemplate : ITemplate
{
private SWT.Components.DataTableColumnInfo _DTColumnInfo;
private ListItemCollection _ListItems;

public MyTemplate(SWT.Components.DataTableColumnInfo toColumnInfo,ListItemCollection taItems)
{
this._DTColumnInfo = toColumnInfo;
this._ListItems = taItems;
}

public void InstantiateIn(Control toContainer)
{
if (this._DTColumnInfo.ControlTypeName == "TextBox ") {
string lcID = toContainer.ID;
lcID = toContainer.ClientID;
TextBox loEdtBox = new TextBox();
loEdtBox.ID = "edt " + this._DTColumnInfo.Name;
loEdtBox.EnableViewState = true;
loEdtBox.DataBinding += new EventHandler(this.OnDataBinding);
loEdtBox.Width = this._DTColumnInfo.Width;
toContainer.Controls.Add(loEdtBox);
if (this._DTColumnInfo.Type == "System.Int32 ") {
CompareValidator loCompareInteger = new CompareValidator();
loCompareInteger.ControlToValidate = loEdtBox.ID;
loCompareInteger.Operator = ValidationCompareOperator.DataTypeCheck;
loCompareInteger.Type = ValidationDataType.Integer;

loCompareInteger.ErrorMessage = "！ ";
toContainer.Controls.Add(loCompareInteger);
}
}
else if (this._DTColumnInfo.ControlTypeName == "DropDownList ")
{
DropDownList loDDL = new DropDownList();
loDDL.ID = "ddl " + this._DTColumnInfo.Name;
loDDL.CssClass = "dropdown_default ";
loDDL.EnableViewState = true;
foreach (ListItem loItem in this._ListItems) {
loDDL.Items.Add(loItem);
}

loDDL.DataBinding += new EventHandler(this.OnDataBinding);
toContainer.Controls.Add(loDDL);
}
else if (this._DTColumnInfo.ControlTypeName == "CheckBox ")
{
CheckBox loChkBox = new CheckBox();
loChkBox.ID = "chk " + this._DTColumnInfo.Name;
loChkBox.EnableViewState = true;
loChkBox.DataBinding += new EventHandler(this.OnDataBinding);
toContainer.Controls.Add(loChkBox);

}
}

public void OnDataBinding(object sender, EventArgs e)
{
GridViewRow loContainer = (GridViewRow)((Control)sender).NamingContainer;
if (this._DTColumnInfo.ControlTypeName == "TextBox ")
{
TextBox loEdtBox = (TextBox)sender;
loEdtBox.Text = ((DataRowView)loContainer.DataItem)[_DTColumnInfo.Name].ToString();
}
else if (this._DTColumnInfo.ControlTypeName == "DropDownList ")
{
DropDownList loDDL = (DropDownList)sender;
ListItem loSelItem = loDDL.Items.FindByValue((((DataRowView)loContainer.DataItem)[_DTColumnInfo.Name].ToString()));
if (loSelItem != null)
{
loSelItem.Selected = true;
}
}
else if (this._DTColumnInfo.ControlTypeName == "CheckBox ")
{
CheckBox loChkBox = (CheckBox)sender;
loChkBox.Checked = Convert.ToBoolean(((DataRowView)loContainer.DataItem)[_DTColumnInfo.Name].ToString());
}
}
}

==========
Page_Load如下：
protected void Page_Load(object sender, EventArgs e)

{
if (!Page.IsPostBack) {

fillGridView( "add ");//根据动态构造的DataTable（并非来自数据库），构建GridView列
addInitial();//对部分控件赋初始值
this.grdChapter.EnableViewState = true;//grdChapter为GridView控件
}
===========
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
问题一 ：
如果将动态构建GridView列的“fillGridView（）”放在“IsPostBack”里面，单击Button后，GridView中我自己定义的TextBox和DropDownList就没有了。为什么？
问题二：
为什么GridView.DataSource == null？
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

问题三：
我将“fillGridView（）”拿到了“IsPostBack”外面，
页面上有一个Button，单击事件中读取Gridview中各单元值，GridView中每一行有edtQuestionNum（TextBox控件）和ddlQuestionType—ropDownList控件）示例代码如下，
foreach (GridViewRow loCurRow in this.grdChapter.Rows) {
if (loCurRow.RowType == DataControlRowType.DataRow) {
if (loCurRow.FindControl( "edtQuestionNum ") != null)
{
Response.Write(((TextBox)loCurRow.FindControl( "edtQuestionNum ")).Text + "|| ");
}
if (loCurRow.FindControl( "ddlQuestionType ") != null)
{
Response.Write(((DropDownList)loCurRow.FindControl( "ddlQuestionType ")).SelectValue+ "> > ");
}
}

}

为什么每次打印在Page上的TextBox是我填写的值，而DropDownList都是第一条的Value？



[解决办法]
this.grdChapter.EnableViewState = true;

这句话就直接在gridview属性中直接设置就可以了,,这样你第一次所取的数据在你单击button后会自动保存的,,,,


gridview.datasource==null,因为你的页面刷新了,,,当然为null了..

呵呵..
[解决办法]
不要放在
if (!Page.IsPostBack) {}
里
[解决办法]
每次定datagrid那dropdownlist邪重新定一次的。