在GridView的PageIndexChanged中保留DropDownList值 [英] Persisting DropDownList Value in PageIndexChanged of GridView

问题描述

  Protected Sub grdView_PageIndexChanging（sender As Object，e As GridViewPageEventArgs）处理grdView.PageIndexChanging 
 
 grdView.SelectedIndex = -1 
 grdView.PageIndex = e.NewPageIndex 
 
'使用数据表在分页时保留DDL值
 
 Dim Data As New DataTable 
 Data.Columns.Add（RowIndex，Type.GetType （System.Int32））
 Data.Columns.Add（SelectedValue，Type.GetType（System.String））
 
作为GridViewRow的每一行在grdView.Rows 
 Dim dd As DropDownList = DirectCast（Row.FindControl（ddlSample），ComboBox）
如果ddl.SelectedValue<> （RowIndex）= Row.RowIndex 
行（SelectedValue）= ddl.SelectedValue 
 Data.Rows .Add（行）
结束如果
下一个
'将数据表传递给会话
 Session（MYDataTable）= Data 
 
 grdView.DataSource = grdDataSource 
 grdView.DataBind（）
如果Session（MYDataTable）IsNot Nothing AndAlso Session（MYDataTable）IsNot DBNull.Value Then 
 Data = CType（Session（MYDataTable）， DataTable）
对于每一行Data.Rows 
如果e.NewPageIndex = row（PageIndex）然后
 Dim ddl As DropDownList = DirectCast（grdView.Rows（row（RowIndex）） ）.FindControl（ddlSample），DropDownList）
 ddl.SelectedValue = row（SelectedValue）
 End If 
 Next 
结束如果
  

上面的代码是我用于持久DropDownList值的代码，但它不起作用如预期的那样。

在我的 GridView 中，我有两个列

第一栏详情：我有员工姓名列表

第二栏详情：每行有一个dropDownlist很多项目。

在我的网格中，我有近100个值，所以我设置了 allowPaging =true并设置 pagesize =10。

我面临的问题是

• 第1步：我在第0页的rowindex 2的下拉列表中选择一个值


• 第2步：将页面更改为5，我在第0页为rowindex 2选择的值也出现在第5页的rowindex 2中，代码。
  

但我想要的是我在第0页的rowindex 2的下拉列表中选择了一个值。 li>

第2步：将页面更改为5，不应选择任何值，因为我没有选择任何值。

步骤3：我再次返回第0页，Rowindex 2中ddl的值应该具有先前选定的值。

编辑

所提及的词典中的值 此处!!

  Dim ddlValues As New Dictionary（Of String，Integer）
对于rowIndex As Integer = 0对于grdOnlineVoter.Rows.Count 
 Dim ddl As ComboBox = grdView.Rows（rowIndex）.FindControl（ddlsample）
如果ddl IsNot Nothing Then 
如果ddl.SelectedIndex> 0 Then 
 Dim ddIndex As Integer = rowIndex 
 ddlValues.Add（ddl.SelectedValue，ddlIndex）
 End If 
 End If 
 Next 
  

但我无法将其重新填充到Dropdownlist中

解决方案

好的，根据你在这里展示的内容，我已经得出了这个结论。

您正在将字典的值保存到特定的行号。那是0-9。但是，行号不会考虑页码。所以我建议你做以下操作：（更改在第6行）

pre $ Dim ddlValues As New Dictionary（Of String，Integer ）
对于rowIndex As Integer = 0对于grdOnlineVoter.Rows.Count
Dim ddl As ComboBox = grdView.Rows（rowIndex）.FindControl（ddlsample）
如果ddl IsNot Nothing则
如果ddl.SelectedIndex> 0然后
Dim ddIndex As Integer = rowIndex +（GridView1.PageIndex * 10）
ddlValues.Add（ddl.SelectedValue，ddlIndex）
End If
End If
下一个


现在页面1的值为：0-9

第2页将有值10-19等。

 Protected Sub grdView_PageIndexChanging(sender As Object, e As GridViewPageEventArgs) Handles grdView.PageIndexChanging

        grdView.SelectedIndex = -1
        grdView.PageIndex = e.NewPageIndex

        ' To persist DDL values at paging using datatable 

        Dim Data As New DataTable
        Data.Columns.Add("RowIndex", Type.GetType("System.Int32"))
        Data.Columns.Add("SelectedValue", Type.GetType("System.String"))

        For Each Row As GridViewRow In grdView.Rows
            Dim ddl As DropDownList = DirectCast(Row.FindControl("ddlSample"), ComboBox)
            If ddl.SelectedValue <> ""  Then
                Dim Rows As DataRow = Data.NewRow
                Rows("RowIndex") = Row.RowIndex
                Rows("SelectedValue") = ddl.SelectedValue
                Data.Rows.Add(Rows)
            End If
        Next
 ' Passing the datatable to session  
 Session("MYDataTable") = Data

 grdView.DataSource = grdDataSource
            grdView.DataBind()
            If Session("MYDataTable") IsNot Nothing AndAlso Session("MYDataTable") IsNot DBNull.Value Then
                Data = CType(Session("MYDataTable"), DataTable)
                For Each row In Data.Rows
                    If e.NewPageIndex = row("PageIndex") Then
                        Dim ddl As DropDownList = DirectCast(grdView.Rows(row("RowIndex")).FindControl("ddlSample"), DropDownList)
                        ddl.SelectedValue = row("SelectedValue")
                    End If
                Next
            End If

The above Code is the code I'm having for Persisting DropDownList value but it is not working as expected.

In my GridView i have two Columns

Details of First column : I have list of employee names

Details of Second Column : It has a dropDownlist in each row with many items in it.

In my grid i have nearly 100 values, So i have set allowPaging="true" and have set pagesize="10".

The problem what I'm facing is

• Step 1 : I'm selecting a value in dropdownlist of rowindex 2 in page 0
• Step 2 : changing the page to 5, the value I selected in page 0 for the rowindex 2 also appears in the page 5 for the rowindex 2 as per my code.

But what i want is

• Step 1 : I'm selecting a value in dropdownlist of rowindex 2 in page 0
• Step 2 : changing the page to 5, no value should be selected as i haven't selected any values in it.
• Step 3 : I i go back again to Page 0 the value of ddl in Rowindex 2 should have the previously selected value.

EDIT

I'm peristing the Values in Dictionary as mentioned here..!!

 Dim ddlValues As New Dictionary(Of String, Integer)
            For rowIndex As Integer = 0 To grdOnlineVoter.Rows.Count
                Dim ddl As ComboBox = grdView.Rows(rowIndex).FindControl("ddlsample")
                If ddl IsNot Nothing Then
                    If ddl.SelectedIndex > 0 Then
                        Dim ddlIndex As Integer = rowIndex
                        ddlValues.Add(ddl.SelectedValue, ddlIndex)
                    End If
                End If
            Next

But i'm unable to repopulate it to the Dropdownlist

解决方案

Alright, based on what you have displayed here I have reached this conclusion.

You are saving the values to the Dictionary to the specific Row number. That is 0-9. However, row numbers does not take pagenumber into consideration. So I recommend you to do the following: (Change is on row 6)

Dim ddlValues As New Dictionary(Of String, Integer)
For rowIndex As Integer = 0 To grdOnlineVoter.Rows.Count
  Dim ddl As ComboBox = grdView.Rows(rowIndex).FindControl("ddlsample")
  If ddl IsNot Nothing Then
      If ddl.SelectedIndex > 0 Then
          Dim ddlIndex As Integer = rowIndex + (GridView1.PageIndex * 10)
          ddlValues.Add(ddl.SelectedValue, ddlIndex)
      End If
  End If
Next

Now page 1 will have values: 0-9

Page 2 will have values 10-19 etc.

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