ASP.net 自定义 GridView 控件

Question

我正在开发自定义 GridView 控件，需要一些帮助。如果我手动输入列名称，我可以让它正确地输出我需要的内容。现在我有两个问题。第一个是动态显示列标题。第二个是动态填充行项目。

默认.aspx

<asp:View id="vCreateNew" runat="server">
            Content Here (View 2)...
            <trac:DataGridView id="gvMain" runat="server"  GridLines="Horizontal"  AutoGenerateColumns="False" > </trac:DataGridView>
        </asp:View>

默认.aspx.vb

Partial Class processes_ProgramTrack_Default
    Inherits Citi.CSPaper.Controls.BasePage
    Protected Sub ProgramTrackNav_MenuItemClick(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.MenuEventArgs) Handles ProgramTrackNav.MenuItemClick
        Dim strSelection As String = ProgramTrackNav.SelectedValue
        Dim sqlDataSource As New SqlDataSource()
        sqlDataSource.ConnectionString = ConfigurationManager.ConnectionStrings("CSPaperWEBConnectionString").ConnectionString
        Select Case strSelection
            ......                
            Case "CreateNew"
                mlvNav.SetActiveView(vCreateNew)
                sqlDataSource.SelectCommand = "SELECT [ProgramNumber], [ProgramName], [ProgramStatus] FROM tblPrgTrackPrograms"
                Dim args As New DataSourceSelectArguments
                gvMain.DataSource = sqlDataSource.Select(args)
                gvMain.DataBind()
            ........
            End Select
    End Sub
End Class

GridViewControl.ascx

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="GridViewControl.ascx.vb"  Inherits="GridViewControl" %>
<asp:GridView ID="GridViewControl" runat="server" >
</asp:GridView>

GridViewControl.ascx.vb

Public Class GridViewControl
    Inherits System.Web.UI.UserControl
    Private _html As New StringBuilder()
    Private _dataSource As IEnumerable
    Private _CssClass As String
    Private _CellSpacing As String
    Public Property DataSource() As IEnumerable
        Get
            Return _dataSource
        End Get
        Set(ByVal value As IEnumerable)
            _dataSource = value
        End Set
    End Property
    Public Overridable Property CssClass() As String
        Get
            Return _CssClass
        End Get
        Set(ByVal value As String)
            _CssClass = value
        End Set
    End Property
    Public Overridable Property CellSpacing() As String
        Get
            Return _CellSpacing
        End Get
        Set(ByVal value As String)
            _CellSpacing = value
        End Set
    End Property
    Private Sub CreateBulletedList()
        Dim dataSource As IEnumerable = Nothing
        Dim i As Integer = 0
        Dim strArr() As String = {"ID", "Name", "Fee"}
        Try
            dataSource = Me._dataSource
        Catch
        End Try

        If Not (dataSource Is Nothing) Then
            _html.Append("<table id=""" & ClientID & """ class=""" & _CssClass & """ CellSpacing=""" & _CellSpacing & """>")
            _html.Append("<thead>" & vbCrLf & "<tr>" & vbCrLf)
            For Each Item As String In strArr
                _html.Append("<th>" & Item & "</th>" & vbCrLf)
            Next
            _html.Append("</tr>" & vbCrLf & "</thead><tbody>" & vbCrLf)
            For Each dataObject As Object In dataSource
                _html.Append("<tr>" & vbCrLf)
                For i = 0 To 2
                    _html.Append("<td>" & vbCrLf)
                    _html.Append(dataObject.Row(i))
                    _html.Append("</td>" & vbCrLf)
                Next
                _html.Append("</tr>" & vbCrLf)
            Next dataObject
            _html.Append("</tbody></table>" & vbCrLf)
        End If
    End Sub
    Public Overrides Sub DataBind()
        MyBase.OnDataBinding(EventArgs.Empty)

        CreateBulletedList()
    End Sub
    Protected Overrides Sub Render(ByVal output As HtmlTextWriter)
        output.Write(_html)
    End Sub
End Class

------------------------------------
| Table Data                       |
------------------------------------
ID  AppName            Environment
2   TestApp            UAT
3   ServerFileMaint    UAT
4   ProgramTrack       Development
5   RegZ_Stmnt_Adj     Active
6   SecInv             Decommission

我不想手动编码 for i = 0 to ...(上限)，但希望动态执行此操作。标题也是如此。我遇到的问题是，如果我不对上限进行硬编码，我会收到一条错误消息，指出无法找到第 3 列。。我在编写第二个 For Each block 以循环包含数据的行时得到此信息。

Answer 1

我想我明白这里发生了什么，以及如何解决它。

对我来说最大的困惑是这个 block :

            For Each dataObject As Object In dataSource
                _html.Append("<tr>" & vbCrLf)
                For i = 0 To 2
                    _html.Append("<td>" & vbCrLf)
                    _html.Append(dataObject.Row(i))
                    _html.Append("</td>" & vbCrLf)
                Next
                _html.Append("</tr>" & vbCrLf)
            Next dataObject

如果 dataSource 是一个 DataSet，那么这种方式是有意义的...但实际上并不是这样，因为相反，您想要引用 Table(0)。如果 dataSource 是一个 DataTable，那么这种方式是有意义的，但实际上并非如此，因为那时您会希望将 For Each dataObject 作为 dataSource.Rows 中的 DataRow 进行循环。但情况似乎并非如此，因为您引用了 dataObject.Row(i)。

您可能想做的是(在粗略/未经测试的代码中)更像是这样的:

            For Each dataObject As DataRow In dataSource.Rows
                _html.Append("<tr>" & vbCrLf)
                For Each col as DataColumn In dataSource.Columns
                    _html.Append("<td>" & vbCrLf)
                    _html.Append(dataObject(col).ToString())
                    _html.Append("</td>" & vbCrLf)
                Next
                _html.Append("</tr>" & vbCrLf)
            Next

这假设数据源是一个数据表，您将循环遍历该表的所有行，然后对于每一行，您将循环遍历数据表中的所有列，并获取该行中每一列的数据，显示它。