来自 CascadingDropDown 中数据库的预填充数据

Question

我在一个网页上有三个CascadingDropDowns，我在我网站的许多地方都使用了这些CascadingDropDowns。它们从数据库中加载了国家、地区和地区名称。我已经成功地与他们绑定数据并将它们设置为级联。但是当用户在我的网站上注册时，我想在三个CascadingDropDowns 中预选三个值。

注册后，我还需要在管理区域查看他们的数据，在这里我还需要预选三个CascadingDropDowns 和用户选择的值。但我不知道该怎么做。

我的网络服务代码：

namespace ZetaSolutions.WebProjects.Web.Modules
{
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.Web.Script.Services.ScriptService()]
    public class PlaceSelection : System.Web.Services.WebService
    {
        [WebMethod]
        public CascadingDropDownNameValue[] BindCountryDropDown(string knownCategoryValues, string category)
        {
            SqlConnection conCountry = new SqlConnection(ZetaConfig.ConnectionString);
            conCountry.Open();

            SqlCommand cmdCountry = new SqlCommand("SELECT * FROM Country ORDER BY Name", conCountry);
            SqlDataAdapter daCountry = new SqlDataAdapter(cmdCountry);
            cmdCountry.ExecuteNonQuery();

            DataSet dsCountry = new DataSet();
            daCountry.Fill(dsCountry);
            conCountry.Close();

            List<CascadingDropDownNameValue> countryDetails = new List<CascadingDropDownNameValue>();

            foreach (DataRow dtRow in dsCountry.Tables[0].Rows)
            {
                string countryId = dtRow["CountryID"].ToString();
                string countryName = dtRow["Name"].ToString();

                countryDetails.Add(new CascadingDropDownNameValue(countryName, countryId));
            }

            return countryDetails.ToArray();
        }

        [WebMethod]
        public CascadingDropDownNameValue[] BindDistrictDropDown(string knownCategoryValues, string category)
        {
            int countryId;
            StringDictionary countryDetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
            countryId = Convert.ToInt32(countryDetails["Country"]);

            SqlConnection conDistrict = new SqlConnection(ZetaConfig.ConnectionString);
            conDistrict.Open();
            SqlCommand cmdDistrict = new SqlCommand("SELECT * FROM District WHERE CountryID=@CountryID ORDER BY Name", conDistrict);
            cmdDistrict.Parameters.AddWithValue("@CountryID", countryId);
            cmdDistrict.ExecuteNonQuery();

            SqlDataAdapter daDistrict = new SqlDataAdapter(cmdDistrict);
            DataSet dsDistrict = new DataSet();
            daDistrict.Fill(dsDistrict);
            conDistrict.Close();

            List<CascadingDropDownNameValue> districtDetails = new List<CascadingDropDownNameValue>();

            foreach (DataRow dtDistrictRow in dsDistrict.Tables[0].Rows)
            {
                string districtId = dtDistrictRow["DistrictID"].ToString();
                string districtName = dtDistrictRow["Name"].ToString();
                districtDetails.Add(new CascadingDropDownNameValue(districtName, districtId));
            }

            return districtDetails.ToArray();
        }

        [WebMethod]
        public CascadingDropDownNameValue[] BindAreaDropDown(string knownCategoryValues, string category)
        {
            int districtId;
            StringDictionary districtDetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
            districtId = Convert.ToInt32(districtDetails["District"]);

            SqlConnection conArea = new SqlConnection(ZetaConfig.ConnectionString);
            conArea.Open();
            SqlCommand cmdArea = new SqlCommand("SELECT * FROM Area WHERE DistrictID=@DistrictID ORDER BY Name", conArea);
            cmdArea.Parameters.AddWithValue("@DistrictID ", districtId);
            cmdArea.ExecuteNonQuery();

            SqlDataAdapter daArea = new SqlDataAdapter(cmdArea);
            DataSet dsArea = new DataSet();
            daArea.Fill(dsArea);
            conArea.Close();

            List<CascadingDropDownNameValue> areaDetails = new List<CascadingDropDownNameValue>();

            foreach (DataRow dtAreaRow in dsArea.Tables[0].Rows)
            {
                string areaId = dtAreaRow["AreaID"].ToString();
                string areaName = dtAreaRow["Name"].ToString();
                areaDetails.Add(new CascadingDropDownNameValue(areaName, areaId));
            }

            return areaDetails.ToArray();
        }
    }
}

我的 aspx 代码：

<table>
    <tr>
        <td>
            Country:
        </td>
        <td>
            <asp:DropDownList ID="ddlCountry" runat="server"></asp:DropDownList>
            <ajaxToolkit:CascadingDropDown ID="CountryCascading" runat="server" Category="Country" TargetControlID="ddlCountry" LoadingText="Loading Countries..." PromptText="Select Country" ServiceMethod="BindCountryDropDown" ServicePath="PlaceSelection.asmx">
            </ajaxToolkit:CascadingDropDown>
        </td>
    </tr>
    <tr>
        <td>
            District:
        </td>
        <td>
            <asp:DropDownList ID="ddlDistrict" runat="server"></asp:DropDownList>
            <ajaxToolkit:CascadingDropDown ID="DistrictCascading" runat="server" Category="District" TargetControlID="ddlDistrict" ParentControlID="ddlCountry" LoadingText="Loading Districts..." PromptText="Select District" ServiceMethod="BindDistrictDropDown" ServicePath="PlaceSelection.asmx">
            </ajaxToolkit:CascadingDropDown>
        </td>
    </tr>
    <tr>
        <td>
            Area:
        </td>
        <td>
            <asp:DropDownList ID="ddlArea" runat="server"></asp:DropDownList>
            <ajaxToolkit:CascadingDropDown ID="AreaCascading" runat="server" Category="Area" TargetControlID="ddlArea" ParentControlID="ddlDistrict" LoadingText="Loading Areas..." PromptText="select Areas" ServiceMethod="BindAreaDropDown" ServicePath="PlaceSelection.asmx">
            </ajaxToolkit:CascadingDropDown>
        </td>
    </tr>
</table> 

谁能告诉我如何解决我的问题？

Answer 1

您需要从“管理员”系统中读取要选择的值，然后使用；

DropDownList.SelectedValue = "value";

在 Page_Load 上进行回发检查。

见：SelectedValue Property

Answer 2

谢谢，这段代码对我有用。

    CascadingDropdownID1.SelectedValue = dsdataset.Table(0).Rows(0)(0).ToString()
    CascadingDropdownID2.SelectedValue = dsdataset.Table(0).Rows(0)(1).ToString()
    CascadingDropdownID3.SelectedValue = dsdataset.Table(0).Rows(0)(2).ToString()

Answer 3

我得到了答案。 ChrisBint，SelectedValue 属性不应该属于 DropDown 本身。它应该是 CascadingDropDown 的。所以现在我的代码是：

CountryCascading.SelectedValue = countryId.ToString();
DistrictCascading.SelectedValue = districtId.ToString();
AreaCascading.SelectedValue = areaId.ToString();

正如 ChrisBint 所说，我在 if (!Page.IsPostBack) 块之外编写了这段代码。