将"Control"转换为文本框并为其指定值

Question

我正在尝试创建一个表单.表单控件名称始终是相同的.但是控制的类型会改变.例如,我有一个名为"first_name"的控件.页面初始化时,它从数据库中检索数据,说明控件的类型(TextBox,DropDownList或CheckBox); 然后在页面上动态创建表单.为了保持视图状态,我在OnInit方法中创建了控件.

protected override void OnInit(EventArgs e)
{
    Control first_name;
    string ControlType = GridView1.Rows[0].Cells[1].Text;
    switch (ControlType)
    {
        case("TextBox"):
            first_name = new Control() as TextBox; first_name.ID = "first_name"; this.Controls.Add(first_name);
            break;
        case("DropDownList"):
            first_name = new Control() as DropDownList; first_name.ID = "first_name"; this.Controls.Add(first_name);
            break;
        case("CheckBox"):
            first_name = new Control() as CheckBox; first_name.ID = "first_name"; this.Controls.Add("first_name");
            break;
    }
}

然后我将控件呈现给页面.

protected override void Render(HtmlTextWriter writer)
{
    writer.Write("first_name: ");
    first_name.RenderControl(writer);
}

接下来,我尝试为控件赋值.这是我遇到问题的地方.我知道当它被全局声明时,它被声明为一个控件并保存这些值.

有没有办法在函数内全局声明它,或者在全局声明后更改控件的类型？

protected void Page_Load(object sender, EventArgs e)
{
    switch (first_name.GetType().ToString())
    {
        case ("TextBox"):
            first_name.Text = "Your First Name...";
            break;
        case ("DropDownList"):
            first_name.Items.Add("Jason");
            first_name.Items.Add("Kelly");
            first_name.Items.Add("Keira");
            first_name.Items.Add("Sandi");
            first_name.Items.Add("Gary");
            break;
        case ("CheckBox"):
            first_name.Checked = true;
            break;
    }        
}

请提供一种我可以完成此任务的方法.

Answer 1

在你OnInit,你应该做的new TextBox(),而不是new Control() as TextBox因为第二只返回null.

你Page_Load会是这样的:

if (first_name is TextBox)
    ((TextBox)first_name).Text = "Your First Name...";
else if (first_name is DropDownList)
{
    var drp = (DropDownList)first_name;
    drp.Items.Add();
    // ...
}