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這是我第一次使用Ajax，這也是我的第一個C＃.NET項目，所以我很新。我正在使用.NET 4.0。在Ajax中加載數據庫值級聯DropDown
我已經成功實現了Ajax級聯下拉，並且在提交時，數據存儲在數據庫中。但是，此頁面還具有「編輯」功能，這意味着如果數據庫中已經填充了所述下拉列表的值，則會顯示「應該」，並允許用戶更改它。這是我卡住的地方。如果在數據庫中已經有這些下拉列表的值，我該如何顯示它？
我確實對我的其他非Ajax字段有try/catch，並且我已經嘗試過在這些上，無濟於事。我也會列出。
代碼背後：
public partial class Research : System.Web.UI.Page
{
//Page Load
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
/Create data table to populate fields with values from the selected record.
DataTable dt = new DataTable();
dt = selectDetails();
//Call Try/Catch Blocks to load fields.
tryRootCauseCategoryDD(cboRootCauseCategory, dt.Rows[0]["rootCauseCategory"].ToString());
tryRootCauseDD(cboRootCause, dt.Rows[0]["rootCause"].ToString());
}
}
protected void tryRootCauseCategoryDD(DropDownList cboRootCauseCategory, string ddSelected)
{
try
{
cboRootCauseCategory.SelectedValue = ddSelected;
}
catch
{
cboRootCauseCategory.SelectedIndex = 0;
}
}
protected void tryRootCauseDD(DropDownList cboRootCause, string ddSelected)
{
try
{
cboRootCause.SelectedValue = ddSelected;
}
catch
{
cboRootCause.SelectedIndex = 0;
}
}
protected DataTable selectDetails()
{
DataTable dt = new DataTable();
dt = dataAccess.ExecuteDataTable
(
"spRecordDetails", dataAccess.DEV, new SqlParameter[1]
{
new SqlParameter ("@vRecID", Request.QueryString["recID"].ToString())
}
);
return dt;
}
ASPX：
<asp:DropDownList ID="cboRootCauseCategory" runat="server"></asp:DropDownList>
<ajaxToolkit:CascadingDropDown ID="ccdRootCauseCategory" runat="server" Category="RootCauseCategory"
TargetControlID="cboRootCauseCategory" PromptText="(Please select:)" LoadingText="Loading.."
ServiceMethod="BindRootCauseCategoryDetails" ServicePath="CascadingDropDown.asmx">
</ajaxToolkit:CascadingDropDown>
<asp:DropDownList ID="cboRootCause" runat="server"></asp:DropDownList>
<ajaxToolkit:CascadingDropDown ID="ccdRootCause" runat="server" Category="RootCause" ParentControlID="cboRootCauseCategory"
TargetControlID="cboRootCause" PromptText="(Please select:)" LoadingText="Loading.."
ServiceMethod="BindRootCauseDetails" ServicePath="CascadingDropDown.asmx">
</ajaxToolkit:CascadingDropDown>
Web服務：
[WebService(Namespace = "http://microsoft.com/webservices/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
//To allow this Web Service to be called from script, using ASP.NET AJAX.
[System.Web.Script.Services.ScriptService()]
public class CascadingDropDown : System.Web.Services.WebService
{
//Database connection string
//private static string strconnection = ConfigurationManager.AppSettings["DEV"].ToString();
private static string strconnection = System.Configuration.ConfigurationManager.ConnectionStrings["DEV"].ConnectionString;
//database connection
SqlConnection conCategory = new SqlConnection(strconnection);
public CascadingDropDown()
{
//Uncomment the following line if using designed components
//InitializeComponent();
}
/// WebMethod to Populate Root Cause Category Dropdown
[WebMethod]
public CascadingDropDownNameValue[] BindRootCauseCategoryDetails(string knownCategoryValues, string category)
{
conCategory.Open();
SqlCommand cmdRootCauseCategory = new SqlCommand
("Select Distinct RootCauseCategory From RootCause", conCategory);
cmdRootCauseCategory.ExecuteNonQuery();
SqlDataAdapter daRootCauseCategory = new SqlDataAdapter(cmdRootCauseCategory);
DataSet dsRootCauseCategory = new DataSet();
daRootCauseCategory.Fill(dsRootCauseCategory);
conCategory.Close();
//create list and add items in it by looping through dataset table
List<CascadingDropDownNameValue> RootCauseCategoryDetails = new List<CascadingDropDownNameValue>();
foreach (DataRow dtrow in dsRootCauseCategory.Tables[0].Rows)
{
//string recID = dtrow["recID"].ToString();
string RootCauseCategory = dtrow["RootCauseCategory"].ToString();
string RootCauseCategoryValue = dtrow["RootCauseCategory"].ToString();
RootCauseCategoryDetails.Add(new CascadingDropDownNameValue(RootCauseCategory,RootCauseCategoryValue));
}
return RootCauseCategoryDetails.ToArray();
}
/// WebMethod to Populate Root Cause Dropdown
[WebMethod]
public CascadingDropDownNameValue[] BindRootCauseDetails(string knownCategoryValues, string category)
{
string rootCauseCategory;
//This method will return a StringDictionary containing the name/value pairs of the currently selected values
StringDictionary rootCauseCategoryDetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
rootCauseCategory = (rootCauseCategoryDetails["RootCauseCategory"]);
conCategory.Open();
SqlCommand cmdRootCause = new SqlCommand("select recID, rootCause from RootCause where rootCauseCategory= @vRootCauseCategory", conCategory);
cmdRootCause.Parameters.AddWithValue("@vRootCauseCategory", rootCauseCategory);
cmdRootCause.ExecuteNonQuery();
SqlDataAdapter daRootCause = new SqlDataAdapter(cmdRootCause);
DataSet dsRootCause = new DataSet();
daRootCause.Fill(dsRootCause);
conCategory.Close();
//create list and add items in it by looping through dataset table
List<CascadingDropDownNameValue> rootCauseDetails = new List<CascadingDropDownNameValue>();
foreach (DataRow dtrow in dsRootCause.Tables[0].Rows)
{
string recID = dtrow["recID"].ToString();
string rootCause = dtrow["rootCause"].ToString();
rootCauseDetails.Add(new CascadingDropDownNameValue(rootCause, recID));
}
return rootCauseDetails.ToArray();
}
}