Telerik MVC网格在运行时从集合或字典中使用动态列

Question

在过去几天搜索之后,我正式陷入困境.我正在研究将对象绑定到Telerik MVC 3 Grid,但问题是它需要动态创建的列(不是自动生成的).其中三列是已知的,其他列是未知的,这是棘手的部分.基本上,它可以像这些例子:

KnownColumn1 | KnownColumn2 | UnknownColumn1 | KnownColumn3 KnownColumn1 | KnownColumn2 | UnknownColumn1 | UnknownColumn2 | UnknownColumn3 | KnownColumn3等

因为我将未知列放在列表中(我也尝试过字典,所以我可以获取列名),这在绑定时对我来说很复杂.我的代码如下:

模型(可以有零到几百行,但是这个模型在List类型的视图模型中,也可以有0到20个动态添加的列)

public class VendorPaymentsGLAccount
{
    public string GeneralLedgerAccountNumber { get; set; }
    public string GeneralLedgerAccountName { get; set; }
    public string DisplayName { get { return string.Format("{0} - {1}", GeneralLedgerAccountNumber, GeneralLedgerAccountName); } }
    public Dictionary<string, double> MonthAmount { get; set; }
    public double Total { get { return MonthAmount.Sum(x => x.Value); } }
    public List<string> Columns { get; set; }
    public List<double> Amounts { get; set; }

    public VendorPaymentsGLAccount() { }
}

查看(注释掉的部分试图使用字典)

<fieldset>
    <legend>General Ledger Account Spend History</legend>
    @if (Model.VendorPaymentsGLAccounts != null)
    {

            <br />
            @(Html.Telerik().Grid(Model.VendorPaymentsGLAccounts)
                    .Name("Grid")
                    .Columns(columns =>
                    {
                        columns.Bound(gl => gl.DisplayName).Title("General Ledger Account").Width(200).Filterable(false).Sortable(false);

                        //foreach (var month in Model.VendorPaymentsGLAccounts[0].MonthAmount)
                        //{
                        //    //columns.Bound(gl => gl.MonthAmount[month.Key.ToString()].ToString()).Title(month.Key.ToString()).Width(100).Filterable(false).Sortable(false);
                        //    //columns.Template(v => Html.ActionLink(v.VoucherID, "VoucherSummary", new { id = v.VoucherID, bu = v.BusinessUnitID, dtt = v.InvoiceDate.Ticks })).Title("Voucher").Width(100);
                        //    columns.Template(gl => Html.ActionLink(gl.MonthAmount[month.Key.ToString()].ToString(), "VoucherSummary")).Title(month.Key.ToString()).Width(100);
                        //}

                        for (int i = 1; i <= (Model.VendorPaymentsGLAccounts[0].Columns.Count() - 1); i++)
                        {
                            string colTemp = Model.VendorPaymentsGLAccounts[0].Columns[i - 1];
                            columns.Template(gl => gl.Amounts[i - 1]).Title(colTemp).Width(100);
                        }

                        columns.Template(gl => String.Format("{0:C}", gl.Total)).Title("Total");
                    })
                    .Sortable()
                    .Pageable()
                    .Filterable()
                    .Footer(true))
    }
    else
    {
        <br />
        @:There are no records that match your selected criteria.
    }
</fieldset>

使用字典方法,我能够使用正确的标题文本正确生成列,但列的值(在我的测试中只有2列)是相同的.有人能帮忙吗？这似乎是一个古怪的问题.只是想弄清楚如何正确地做到这一点.

更新:这是使用字典方法显示问题的屏幕截图.列标题正确,但两个动态列的值相同.

Answer 1

使用带有Telerik网格控件的动态定义列可能很棘手.但在你的情况下,它主要是一个典型的闭包陷阱.

在以下循环中,编译器将绑定gl => gl.Amounts[i - 1]变量的每个实例i并在以后对其进行评估:

for (int i = 1; i <= (Model.VendorPaymentsGLAccounts[0].Columns.Count() - 1); i++)
{
  string colTemp = Model.VendorPaymentsGLAccounts[0].Columns[i - 1];
  columns.Template(gl => gl.Amounts[i - 1]).Title(colTemp).Width(100);
}

实际上,它是在循环结束后进行评估的.因此i将始终具有导致循环完成的值.

修复是使用临时变量:

for (int i = 1; i <= (Model.VendorPaymentsGLAccounts[0].Columns.Count() - 1); i++)
{
  string colTemp = Model.VendorPaymentsGLAccounts[0].Columns[i - 1];
  int columnIndex = i - 1;
  columns.Template(gl => gl.Amounts[columnIndex]).Title(colTemp).Width(100);
}