如何将默认值设置为下拉列表控件？

我的网页上有一个下拉列表控件。 我已将数据表绑定到dropdownlist控件，如下所示 –

lstDepartment.DataTextField = "DepartmentName"; lstDepartment.DataValueField = "DepartmentID"; lstDepartment.DataSource = dtDept; lstDepartment.DataBind(); 

在页面加载事件中，我想从我的其他表字段中将默认值设置为下拉列表控件。

这该怎么做？

Answer 1

在您的DataBind() ：

 lstDepartment.SelectedIndex = 0; //first item or lstDepartment.SelectedValue = "Yourvalue" or //add error checking, just an example, FindByValue may return null lstDepartment.Items.FindByValue("Yourvalue").Selected = true; or //add error checking, just an example, FindByText may return null lstDepartment.Items.FindByText("Yourvalue").Selected = true; 

Answer 2

如果您知道默认值项的索引，只需

 lstDepartment.SelectedIndex = 1;//the second item 

或者如果您知道要设置的值，只需

 lstDepartment.SelectedValue = "the value you want to set"; 

Answer 3

假设另一个表中的DropDownList控件还包含DepartmentName和DepartmentID：

 lstDepartment.ClearSelection(); foreach (var item in lstDepartment.Items) { if (item.Value == otherDropDownList.SelectedValue) { item.Selected = true; } } 

Answer 4

 lstDepartment.DataTextField = "DepartmentName"; lstDepartment.DataValueField = "DepartmentID"; lstDepartment.DataSource = dtDept; lstDepartment.DataBind(); 'Set the initial value: lstDepartment.SelectedValue = depID; lstDepartment.Attributes.Remove("InitialValue"); lstDepartment.Attributes.Add("InitialValue", depID); 

并在您的取消方法：

 lstDepartment.SelectedValue = lstDepartment.Attributes("InitialValue"); 

在您的更新方法中：

 lstDepartment.Attributes("InitialValue") = lstDepartment.SelectedValue;