Question

我遇到了使用数据库中的数据填充ASP DropDownList的问题，我正在尝试使用ajax和jquery，遵循教程但添加了我自己的数据。我遇到的问题是，当页面加载下拉列表为空时，代码在下面。

Html部分

<div id="mainitem1" class="mainItem" style="background-color: #000">

                <div class="box" style="top: 20%; position: absolute; width: 60%; z-index: 1; height: 70%; background-color: #e8e8e8; left: 32%; font-weight: bold; font-size: 1.3vw;">
                    <div id="divdistSearch" style="position: relative; width: 100%; height: 100%; top: 0px; left: 0px;">
                                 <table>
                                     <tr>
                                         <td></td>
                                         <td>
                                             <asp:DropDownList ID="ddlStates" runat="server"></asp:DropDownList>
                                         </td> 
                                     </tr>
                                 </table>
                    </div>
                </div>
                <img id="mainitem1-image" alt="" src="/powertap/images/Background1.jpg" style="position: absolute; top: 0px; left: 0px" />
                <img id="mainitem1-image1" alt="" src="/powertap/images/taps-and-text.png" style="position: absolute; margin-left: auto; margin-right: auto; left: 0; right: 0;" />
            </div>
        </div>

这是Jquery Part，我在separaet .js文件中有这个，但我已经链接到它，在头部

$(function () {
$.ajax({
    type: "POST",
    url: "Default.aspx/GetStates",
    data: '{}',
    contenType: "application/json; charset=utf-8",
    dataType: "json",
    success: function (r) {
        var ddlStates = $("[id*=ddlStates]");
        ddlStates.empty().append('<option selected="selected" value="0">Please select</option>');
        $.each(r.d, function () {
            ddlStates.append($("<option></option>").val(this['Value']).html(this['Text']));
        });
      }
  });
});

这是VB中的代码部分，无法弄清楚我缺少的东西。

Imports System.Data
Imports System.Web.Services
Imports System.Configuration
Imports System.Data.SqlClient
Public Class _Default103
   Inherits System.Web.UI.Page
               Protected Sub Page_Load(ByVal sender As Object, ByVal e As       System.EventArgs) Handles Me.Load
    If Not Session("isLoggedIn") Then
        price_file.Visible = False
        checkstock_icon.Visible = False
        checkstock_title.Visible = False
    End If
  End Sub

<WebMethod()> _
Public Shared Function GetStates() As List(Of ListItem)
    Dim query As String = "SELECT Id, State FROM States"
    Dim constr As String = ConfigurationManager.ConnectionStrings("DistData").ConnectionString
    Using con As New SqlConnection(constr)
        Using cmd As New SqlCommand(query)
            Dim states As New List(Of ListItem)()
            cmd.CommandType = CommandType.Text
            cmd.Connection = con
            con.Open()
            Using sdr As SqlDataReader = cmd.ExecuteReader()
                While sdr.Read()
                    states.Add(New ListItem() With {
                               .Value = sdr("Id").ToString(), _
                               .Text = sdr("State").ToString() _
                               })
                End While
            End Using
            con.Close()
            Return states
        End Using
    End Using
  End Function
End Class

Answer 1

我认为在您的示例中使用JSON背后没有任何价值。但无论如何，你首先没有绑定你的下拉列表。初始绑定可以添加到页面加载事件中。

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As       System.EventArgs) Handles Me.Load
If !IsPostBack//Make sure this is only filled if the page is not posted back
 GetStates();

获取DropDownList以从服务器转换数据

1 个答案: