Question

我有两个复选框列表CandidateName和Payment，以及一个下拉列表。用户可以在复选框列表中进行多项选择，在下拉列表中进行一次选择。我将chechboxlists和dropdownlist的数据填充到嵌套在UpdatePanel里面的Panel中，其中gridview存在。当我点击Add Button打开Panel时，所有数据都正确填充。当我尝试通过＆＃34; for循环＆＃34;保存多个选定的复选框列表时在调试时，它不会进入循环内部以使用逗号累积已检查数据以保存在数据库中。相反，在chekcing＆＃34; if（cblPayment1.Items [j] .Selected == true）＆＃34;之后，它跳过另一个查询语句。请帮我指教。

 protected void btnAddNew_Click(object sender, EventArgs e)
{
    try
    {

        string strcbl1 = string.Empty;
        string strcbl2 = string.Empty;
        compCon = new SqlConnection(strConnectionString);
        compCon.Open();


        for (int i = 0; i < cblCandidateName1.Items.Count-1; i++)
        {
            if (cblCandidateName1.Items[i].Selected ==true)
            {
                strcbl1 = strcbl1 + cblCandidateName1.Items[i].Value.ToString() + ",";
            }
        }

        for (int j = 0; j < cblPayment1.Items.Count - 1; j++)
        {
            if (cblPayment1.Items[j].Selected == true)
            {
                strcbl2 += cblPayment1.Items[j].Value.ToString() + ",";
            }
        }


       string InsertSchedule = "INSERT INTO ScheduleEmail(CANDIDATE_ID, PAYMENT_ID,     TEMPLATE_ID)VALUES(@strCID, @strPID, @strCourseID)";
        SqlCommand InsertScheduleCommand = new SqlCommand(InsertSchedule, compCon);
        InsertScheduleCommand.Connection = compCon;


        InsertScheduleCommand.Parameters.AddWithValue(@"strCID", strcbl1);
        InsertScheduleCommand.Parameters.AddWithValue(@"strPID", strcbl2);
        InsertScheduleCommand.Parameters.AddWithValue(@"strCourseID", strCourseID);

        InsertScheduleCommand.ExecuteNonQuery();
        compCon.Close();
    }
    catch (Exception ex)
    {
        ShowPopUpMsg("Data is failed to save in table. Please contact your system administrator \n" + ex.ToString());
    }
    finally
    { 
    DispalyGridViewScheduleEmail();

    compCon.Close();
    }

}

这是我的HTML代码。

<!--Panel to add new record--><asp:Panel ID="panelAddNew" runat="server" 
style="display:none; background-color:gray;"        ForeColor="Black" Width="500" Height="550">
<asp:Panel ID="panelAddNewTitle" runat="server" 
 style="cursor:move;font-family:Tahoma;                       
 padding:2px;" HorizontalAlign="Center" BackColor="Blue" ForeColor="White" Height="25">
<b>Add New</b></asp:Panel>
 <table width="100%" style="padding:5px">
            <tr>
            <td colspan="3">
                <asp:Label ID="lblStatus1" runat="server"></asp:Label>
            </td>
            </tr>
            <tr>
                <td><b>Select Candidate Name(s)</b></td>
                <td><b>:</b></td>
                <td><asp:CheckBoxList ID="cblCandidateName1" runat="server" RepeatColumns="3" RepeatDirection="Horizontal" RepeatLayout="table">
                </asp:CheckBoxList>
                </td>
            </tr>
            <tr>
                <td><b>Select Payments</b></td>
                <td><b>:</b></td>
                <td>
                   <asp:CheckBoxList ID="cblPayment1" runat="server" RepeatDirection="Horizontal" RepeatLayout="Table"></asp:CheckBoxList>
                </td>
            </tr>


            <tr>
                <td><b>Course Name</b></td>
                <td><b>:</b></td>
                <td> <asp:DropDownList ID="ddlCourseName" runat="server">      </asp:DropDownList>            


                </td>
            </tr>
        </table>
        <br />
            <div align="center">
            <asp:Button ID="btnAddNew2" runat="server" Width="70" Text="Add" OnClick="btnAddNew_Click"  ValidationGroup="add"/>
            &nbsp;

            <asp:Button ID="btnCancel1" runat="server" Width="70" Text="Cancel" CausesValidation="false" OnClick="Cancel_Click" ValidationGroup="add"/>
        </div>
    </asp:Panel>   
        <!--End of Panel to add new record-->

Answer 1

由于这种情况，for和cblCandidateName1.Items的最后一项都不会执行您的cblPayment1.Items个阻止：

for (int i = 0; i < cblCandidateName1.Items.Count-1; i++)

和

for (int j = 0; j < cblPayment1.Items.Count - 1; j++)

您需要将两个for块更改为以下

for (int i = 0; i < cblCandidateName1.Items.Count; i++)
{
    if (cblCandidateName1.Items[i].Selected ==true)
    {
        strcbl1 = strcbl1 + cblCandidateName1.Items[i].Value.ToString() + ",";
    }
}

for (int j = 0; j < cblPayment1.Items.Count; j++)
{
    if (cblPayment1.Items[j].Selected == true)
    {
        strcbl2 += cblPayment1.Items[j].Value.ToString() + ",";
    }
}

<强>更新

即使您查看了部分付款清单，似乎cblPayment1.Items[j].Selected始终为假。可能的原因可能是您在cblPayment1方法中填充Page_Load项，但未在if (!this.IsPostBack)块内填充

protected void Page_Load(object sender, EventArgs e)
{
    cblPayment1.DataSource = .... ;
    cblPayment1.DataBind();
}

当您点击保存按钮时，Page_Load方法将在btnAddNew_Click之前执行，因此cblPayment1将会重新填充，并且当您启用时，所有项目都将被选中达到btnAddNew_Click方法。您需要更改Page_Load代码，如下所示

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        cblPayment1.DataSource = .... ;
        cblPayment1.DataBind();
    }
}

Answer 2

首先尝试不以您所显示的方式在循环中使用字符串连接。这是一个坏习惯，并且在以后会导致性能问题，因为每个连接都会为字符串重新分配新内存，然后将其复制到该位置。

如何在此代码中使用一些lambdas？它将大大简化：

strcbl1=string.Join(",", cblCandidateName1.Items.Where(x=>x.Selected));
strcbl2=string.Join(",", cblPayment1.Items.Where(x=>x.Selected));

Answer 3

首先，尽量不要以问题中显示的方式在循环中使用字符串连接。这是一个坏习惯，并在以后导致性能问题，因为每个串联都会为字符串重新分配新的内存，然后将其复制到该位置。

如何在此代码中使用一些lambda？这样会大大简化：

strcbl1 = string.Join(",", cblCandidateName1.Items.Where(x=>x.Selected));

strcbl2 = string.Join(",", cblPayment1.Items.Where(x=>x.Selected));

如何将多个选中的checkboxlist保存到数据库asp .net c＃

3 个答案: