Question

我有一个ASP DropDownList，当从中选择一个项目时它会消失。应该发生的是另一个DropDownList应该出现，但它也没有显示。

    <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <meta charset="utf-8" />
    <title>KYFB Black Book</title>
    <link rel="stylesheet" href="blackbook.css" />
</head>
<body>
    <img class="logo" src="images/logo.jpg"/>
    <p id="home_title" runat="server">Black Book</p>
    <form id="sign_in_form" runat="server">
    <div>
        <input id="username_field" runat="server" type="text" placeholder="Username" name="username" /> <br />
        <input id="password_field" runat="server" type="password" placeholder="Password" name="password" /> <br /> <br />
        <input id="submit_button" runat="server" type="submit" value="Sign In" onclick="ajaxFunction();" />
    </div>
    </form>

    <form id="selection_form" runat="server">
        <div id="counties_div" style="display: block; width: 15%; margin: auto;" runat="server">
            <p id="county_list_title" style="color:white;" runat="server">Select a county</p>
            <asp:DropDownList ID="county_list" AutoPostBack="True" OnSelectedIndexChanged="countyChange" runat="server"></asp:DropDownList>
            <br />
            <p id="committee_list_title" style="color:white;" runat="server">Select a committee</p>
            <asp:DropDownList ID="committee_list" AutoPostBack="true" OnSelectedIndexChanged="committeeChange" runat="server"></asp:DropDownList>
        </div>
    </form>
</body>
</html>

编辑：在被要求提供更多代码之后，这里是所有的C＃。

public partial class _Default : System.Web.UI.Page
{


    protected void Page_Load(object sender, EventArgs e)
    {
        selection_form.Visible = false;
        counties_div.Visible = false;
        submit_button.ServerClick += new EventHandler(this.submitPressed);
    }

    public void displayAlert(String message)
    {
        ClientScript.RegisterStartupScript(this.GetType(), "myalert", "alert('" + message + "');", true);
    }

    public void submitPressed(Object sender, EventArgs e)
    {
        if (username_field.Value == "")
        {

            this.displayAlert("Enter your username");
        }
        else if (password_field.Value == "")
        {

            this.displayAlert("Enter your password");
        }
        else
        {
            // Validate credentials

            String username = username_field.Value;
            String password = password_field.Value;

            WebRequest request = WebRequest.Create("https://membershipwebapp.azurewebsites.net/signin");
            request.Method = "GET";
            request.ContentType = "application/json";
            String encoded = Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1").GetBytes(username + ":" + password));
            request.Headers.Add("Authorization", "Basic " + encoded);

            HttpWebResponse response = request.GetResponse() as HttpWebResponse;

            if (response.StatusCode == HttpStatusCode.OK)
            {
                var reader = new StreamReader(response.GetResponseStream());
                JavaScriptSerializer js = new JavaScriptSerializer();
                var objText = reader.ReadToEnd();
                var objArray = js.Deserialize<dynamic>(objText);

                // Check if JSON array is empty

                if (objArray.Length == 0)
                {
                    // Display sign in error
                    this.displayAlert("Username or password was incorrect.Try again.");
                }
                else
                {
                    Dictionary<String, dynamic> userDictionary = objArray[0];
                    home_title.InnerHtml = "Welcome, " + userDictionary["FirstName"];

                    // Display black book data

                    sign_in_form.Visible = false;

                    this.getCounties();
                    selection_form.Visible = true;
                    counties_div.Visible = true;
                    committee_list_title.Visible = false;
                    committee_list.Visible = false;
                }
            }
            else
            {
                // Display error message
                this.displayAlert("An error occurred");
            }

            response.Close();
        }
    }

    public void countyChange(Object sender, EventArgs e)
    {
        if (county_list.Items[county_list.SelectedIndex].Value != "")
        {
            this.getCommittees();
            committee_list_title.Visible = true;
            committee_list.Visible = true;
        }
    }

    public void getCounties()
    {
        WebRequest request = WebRequest.Create("https://membershipwebapp.azurewebsites.net/counties");
        request.Method = "GET";
        request.ContentType = "application/json";

        HttpWebResponse response = request.GetResponse() as HttpWebResponse;

        if (response.StatusCode == HttpStatusCode.OK)
        {
            var reader = new StreamReader(response.GetResponseStream());
            JavaScriptSerializer js = new JavaScriptSerializer();
            var objText = reader.ReadToEnd();
            var objArray = js.Deserialize<dynamic>(objText);

            // Check if JSON array is empty

            if (objArray.Length == 0)
            {
                // Display error
                this.displayAlert("Error getting counties");
            }
            else
            {

                county_list.Items.Add("");

                for (int i = 0; i < objArray.Length; i++)
                {
                    // Get dictionary and add county name to list

                    Dictionary<String, dynamic> countyDictionary = objArray[i];
                    String countyName = countyDictionary["county"];
                    county_list.Items.Add(countyName);

                }
            }
        }
        else
        {
            // Display error message
            this.displayAlert("Error getting counties");
        }

        response.Close();
    }

    public void getCommittees()
    {
        String selectedCounty = county_list.Items[county_list.SelectedIndex].Value;
        String url = "https://membershipwebapp.azurewebsites.net/committee/" + selectedCounty;
        WebRequest request = WebRequest.Create(url);
        request.Method = "GET";
        request.ContentType = "application/json";

        HttpWebResponse response = request.GetResponse() as HttpWebResponse;

        if (response.StatusCode == HttpStatusCode.OK)
        {
            var reader = new StreamReader(response.GetResponseStream());
            JavaScriptSerializer js = new JavaScriptSerializer();
            var objText = reader.ReadToEnd();
            var objArray = js.Deserialize<dynamic>(objText);

            // Check if JSON array is empty
            this.displayAlert("committee array length: " + objArray.Length);

            if (objArray.Length == 0)
            {
                // Display error
                this.displayAlert("Error getting committees");
            }
            else
            {
                committee_list.Items.Add("");

                for (int i = 0; i < objArray.Length; i++)
                {
                    // Get dictionary and add county name to list

                    Dictionary<String, dynamic> committeeDictionary = objArray[i];
                    String committeeName = committeeDictionary["committee_name"];
                    committee_list.Items.Add(committeeName);
                    // committeeSelect.Items.Add(committeeName);
                }
            }
        }
        else
        {
            // Display error message
            this.displayAlert("Error getting committees");
        }

        response.Close();
    }

    public void committeeChange(object sender, EventArgs e)
    {
        if (committee_list.Items[committee_list.SelectedIndex].Value != "")
        {
            // Display committee member info
        }
    }
}

选择县之前

选择县后

选择项目后DropDownList不可见

0 个答案: