asp.net - 下拉所选索引在页面加载时更改

Question

我有一个下拉框，它根据其值填充文本框值。它在更改时触发，但在页面加载时不会触发。如何让它在页面加载时触发？

   protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {     
   TextBox3.Text = DropDownList1.SelectedValue;
        TextBox12.Text = DropDownList1.SelectedValue;
        TextBox21.Text = DropDownList1.SelectedValue;

     //etc

Answer 1

Tim Schmelter 对钱的评论是正确的。

// Wire up to the page load event
protected void Page_Load(object sender, System.EventArgs e)
{
   updateTextBoxes();
}

// Wire up to the select index-changed event
protected void DropDownList1_SelectIndexChanged( object sender, EventArgs e )
{
    updateTextBoxes();
}


// your workhorse method
protected void updateTextBoxes()
{
   TextBox3.Text  = DropDownList1.SelectedValue;
   TextBox12.Text = DropDownList1.SelectedValue;
   TextBox21.Text = DropDownList1.SelectedValue;

   // etc.
}

Answer 2

它不会在页面加载时自动调用，您必须“手动”调用它：

 void Page_Load(object sender, System.EventArgs e) {

     // ....

     DropDownList1_SelectedIndexChanged(DropDownList1, e);

 }

Answer 3

SelectedIndexChanged响应用户驱动的更改而触发。将分配逻辑移动到另一个方法，Page_Load并从您的事件处理程序手动调用它。