Question

我有一个提交按钮，在提交按钮上单击我想检查我的下拉列表的选定索引是否已更改。如果是，则应调用函数。

我不知道如何在asp.net C＃中做到这一点，需要帮助。

<asp:DropDownList ID="ddlIncidentStatus" runat="server" 
    Enabled="false" 
    Display="Dynamic"  
    AppendDataBoundItems="True"
    AutoPostBack="true" 
    CssClass="form-control">
    <asp:ListItem Value="0">- Select Incident Status -</asp:ListItem>
</asp:DropDownList>

protected void btnSave_Click(object sender, System.EventArgs e) 
{
    if ((SaveToMemory() > 0)) 
    {
        //here i want to check if ddlIncidentStatus has change the value or not
        Response.Redirect(("IncidentReport_New.aspx?OHSIncidentID=" +
            Encryption.EncryptParameter(_incident.OHSIncidentID.ToString())));
        }            
    }
}

Answer 1

Example.aspx

<%@ Page Title="Home Page" Language="C#" AutoEventWireup="true"   
CodeBehind="Default.aspx.cs" Inherits="DropDownListExample._Default" %>  
<!DOCTYPE html>  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
    <title></title>  
</head>  
<body>  
    <form id="form1" runat="server">  
        <p>Select a City of Your Choice</p>  
        <div>  
            <asp:DropDownList ID="DropDownList1" runat="server" >  
            <asp:ListItem Value="">Please Select</asp:ListItem>  
            <asp:ListItem>New Delhi </asp:ListItem>  
            <asp:ListItem>Greater Noida</asp:ListItem>  
            <asp:ListItem>NewYork</asp:ListItem>  
            <asp:ListItem>Paris</asp:ListItem>  
            <asp:ListItem>London</asp:ListItem>  
        </asp:DropDownList>  
        </div>  
        <br />  
        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Submit" />  
        <br />  
        <br />  
        <asp:Label ID="Label1" runat="server" EnableViewState="False"></asp:Label>  
    </form>  
</body>  
</html>

Example.aspx.cs

protected void Button1_Click(object sender, EventArgs e)  
        {  
            if (DropDownList1.SelectedValue == "")  
            {  
                Label1.Text = "Please Select a City";  
            }  
            else  
                Label1.Text = "Your Choice is: " + DropDownList1.SelectedValue;  
        }

单击按钮时如何检查下拉索引？

1 个答案: