Question

我正在尝试根据Dropdownlist中的选定值显示某些文本框。出于某种原因，它不起作用 - 当在下拉列表中选择特定项目时，页面上没有任何输入框可见。希望得到反馈。提前谢谢。

以下是相关代码：

aspx页面：

<asp:DropDownList ID="AreaDropDownList" runat="server" OnSelectedIndexChanged="AreaDropDownList_SelectedIndexChanged" AutoPostBack="True">
            <asp:ListItem></asp:ListItem>
            <asp:ListItem>Rectangle</asp:ListItem>
            <asp:ListItem>Triangle</asp:ListItem>
            <asp:ListItem>Trapezoid</asp:ListItem>
            <asp:ListItem>Circle</asp:ListItem>
            <asp:ListItem>Sector Of Circle</asp:ListItem>
            <asp:ListItem>Ellipse</asp:ListItem>
        </asp:DropDownList>

       <asp:TextBox ID="InputTextBox1" runat="server" AutoPostBack="True" Visible="TRUE"></asp:TextBox>
       <asp:TextBox ID="InputTextBox2" runat="server" AutoPostBack="True" Visible="TRUE"></asp:TextBox>
       <asp:TextBox ID="InputTextBox3" runat="server" AutoPostBack="True" Visible="TRUE"></asp:TextBox>

aspx.cs页面：

protected void AreaDropDownList_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (AreaDropDownList.SelectedValue == "")
            {
                InputTextBox1.Visible = false;
                InputTextBox2.Visible = false;
                InputTextBox3.Visible = false;
            }

            else if (AreaDropDownList.SelectedValue == "Rectangle")
            {
                InputTextBox1.Visible = true;
                InputTextBox2.Visible = true;
                InputTextBox3.Visible = false;
            }

            else if (AreaDropDownList.SelectedValue == "Triangle")
            {
                InputTextBox1.Visible = true;
                InputTextBox2.Visible = true;
                InputTextBox3.Visible = false;
            }

            else if (AreaDropDownList.SelectedValue == "Trapezoid")
            {
                InputTextBox1.Visible = true;
                InputTextBox2.Visible = true;
                InputTextBox3.Visible = true;
            }

            else if (AreaDropDownList.SelectedValue == "Circle")
            {
                InputTextBox1.Visible = true;
                InputTextBox2.Visible = false;
                InputTextBox3.Visible = false;
            }

            else if (AreaDropDownList.SelectedValue == "Sector")
            {
                InputTextBox1.Visible = true;
                InputTextBox2.Visible = true;
                InputTextBox3.Visible = false;
            }

            else if (AreaDropDownList.SelectedValue == "Ellipse")
            {
                InputTextBox1.Visible = true;
                InputTextBox2.Visible = true;
                InputTextBox3.Visible = false;
            }
     }

Answer 1

也许您需要使用.Text属性而不是.SelectedValue 在If语句中。

 if (AreaDropDownList.Text == "")
            {
                InputTextBox1.Visible = false;
                InputTextBox2.Visible = false;
                InputTextBox3.Visible = false;
            }

Answer 2

在M. Ayoub的帮助下，我能够通过稍微改变代码逻辑来解决问题。以下代码放在Page_Load事件函数中，现在我可以控制哪个文本框可见：

if ((RadioButtonList1.SelectedValue != "Area Calculator") &&   (RadioButtonList1.SelectedValue != "Trigonometric Calculator")
            && (RadioButtonList1.SelectedValue != "Area Calculator"))
            {
                arithmetic.Visible = false;
                trig.Visible = false;
                CalcArea.Visible = false;
        }

基于M. Ayoub的反馈做出了另外两个更改：第一个是使用SelectedItem.Text而不是SelectedValue作为下拉列表。第二个是在AreaDropDownList_SelectedIndexChanged中有一个else块。代码如下：

 protected void AreaDropDownList_SelectedIndexChanged(object sender, EventArgs e)
        {
 if (AreaDropDownList.SelectedItem.Text == "")
{
inputbox1.Visible = false;
                inputbox2.Visible = false;
                inputbox3.Visible = false;
                }
else if (AreaDropDownList.SelectedItem.Text == "Rectangle")
            {
inputbox1.Visible = true;
                inputbox2.Visible = true;
                inputbox3.Visible = false;

            }

else if (AreaDropDownList.SelectedItem.Text == "Triangle")
            {
               inputbox1.Visible = true;
                inputbox2.Visible = true;
                inputbox3.Visible = false;
            }

else if (AreaDropDownList.SelectedItem.Text == "Trapezoid")
            {
inputbox1.Visible = true;
                inputbox2.Visible = true;
                inputbox3.Visible = true;
            }

else if (AreaDropDownList.SelectedItem.Text == "Circle")
            {
inputbox1.Visible = true;
                inputbox2.Visible = false;
                inputbox3.Visible = false;

            }

else if (AreaDropDownList.SelectedItem.Text == "Sector")
            {

               inputbox1.Visible = true;
                inputbox2.Visible = true;
                inputbox3.Visible = false;
            }

else if (AreaDropDownList.SelectedItem.Text == "Ellipse")
            {
inputbox1.Visible = true;
                inputbox2.Visible = true;
                inputbox3.Visible = false;

            }

            else
            {
                inputbox1.Visible = true;
                inputbox2.Visible = true;
                inputbox3.Visible = true;
            }

C＃ASP.Net - 如何根据DropDownList中的选定值显示TextBox

2 个答案: