C# .NET GridView行在回发时为空
在回发后填充GridView后，我很难对其行进行迭代 总之，有两个下拉列表可确定应在GridView中显示的数据。页面最初只加载了两个下拉列表，在此阶段没有GridView。从下拉列表中选择值后，用户通过按钮提交页面。然后，代码将调用db来检索数据并将其绑定到GridView。我已经设法让它工作了 问题在于GridView有一列，用户可以在其中编辑itemtemplate中保存的文本框中的值。如果用户更改文本框中的值并提交页面，当我尝试迭代GridView的行时，它会告诉我没有要迭代的行。当我可以看到前端中可用的行和数据时，我不明白为什么会发生这种情况 但是，如果我们删除了用户选择下拉列表的步骤，并在初始页面加载时填充GridView，我实际上可以遍历这些行 因此，如果GridView绑定在按钮单击事件中，则ViewState就好像没有持久化回发之间的行数 谁能给我解释一下，发生了什么事 以下是VB.NET中的代码：C# .NET GridView行在回发时为空,c#,.net,vb.net,gridview,viewstate,C#,.net,Vb.net,Gridview,Viewstate,在回发后填充GridView后，我很难对其行进行迭代 总之，有两个下拉列表可确定应在GridView中显示的数据。页面最初只加载了两个下拉列表，在此阶段没有GridView。从下拉列表中选择值后，用户通过按钮提交页面。然后，代码将调用db来检索数据并将其绑定到GridView。我已经设法让它工作了 问题在于GridView有一列，用户可以在其中编辑itemtemplate中保存的文本框中的值。如果用户更改文本框中的值并提交页面，当我尝试迭代GridView的行时，它会告诉我没有要迭代的行。当我可
Protected Sub Me_Load(ByVal sender As Object, ByVal e As EventArgs) _
Handles Me.Load
End Sub
Protected Sub BtnGetData_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles BtnGetData.Click
Dim ddlFirstValue As Integer = DropDownListOne.SelectedValue
Dim ddlSecondValue As Integer = DropDownListSecond.SelectedValue
MyGridView.DataSource = GetData(ddlFirstValue, ddlSecondValue)
MyGridView.DataBind()
End Sub
Protected Sub BtnSubmit_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles BtnSubmit.Click
For Each row As GridViewRow In MyGridView.Rows 'this returning 0 rows
'Do something
Next
End Sub
不是100%确定你在问什么。所以你点击一个按钮来填充你的gridview，然后点击另一个按钮来提交对它的任何更改？但是当你提交它时，没有行？是的，没错，没有行。当我尝试迭代GridView.Rows时，它表示返回0行。
<%@ Page Language="VB" AutoEventWireup="false"
CodeFile="Default.aspx.vb" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>
Demo of using DropDown Lists to Filter Data for
Editable DataGrid
</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Literal ID="theLiteral" runat="server" />
</div>
<br />
<div>
<asp:GridView ID="myGridView" runat="server"
AutoGenerateColumns="false"
DataKeyNames="weight, cost, Description">
<Columns>
<asp:BoundField DataField="weight" HeaderText="Weight" />
<asp:BoundField DataField="cost" HeaderText="Cost" />
<asp:TemplateField HeaderText="Description">
<ItemTemplate>
<asp:TextBox runat="server" ID="descId"
Text='<%# Bind("Description") %>' />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView><br />
Get Items With Weight >=:<br />
<asp:DropDownList ID="DropDownListOne" runat="server">
<asp:ListItem Text="1" Value="1" />
<asp:ListItem Text="2" Value="2" />
<asp:ListItem Text="5" Value="5" />
</asp:DropDownList><br />
Get Items With Cost >=:<br />
<asp:DropDownList ID="DropDownListSecond" runat="server">
<asp:ListItem Text="1" Value="1" />
<asp:ListItem Text="5" Value="5" />
<asp:ListItem Text="51" Value="51" />
<asp:ListItem Text="101" Value="101" />
</asp:DropDownList><br />
<asp:Button ID="BtnGetData" runat="server" Text="Get Data" /><br />
<asp:Button ID="BtnSubmit" runat="server" Text="Submit" /><br />
</div>
</form>
</body>
</html>
' Just some DataItem to stick in an IEnumerable Array to be
' bound to CreativeInCode's MyGridView
public Class InventoryItem
Public Sub New (
ByVal iWeight As Integer,
ByVal iCost As Integer,
ByVal iDescription As String)
weight = iWeight
cost = iCost
description = iDescription
End Sub
' Automatic VB.NET properties can be read about here:
' http://msdn.microsoft.com/en-us/library/dd293589.aspx
Public Property weight As Integer
Public Property cost As Integer
Public Property description As String
End Class
' The code behind for Default.aspx starts here
Partial Class _Default
Inherits System.Web.UI.Page
' Data to play with
Public storeItems As InventoryItem() =
{
New InventoryItem(10, 20, "PaperWeight"),
New InventoryItem(1, 1, "Feather"),
New InventoryItem(2000, 20000, "Used SUV"),
New InventoryItem(3, 50, "Biology TextBook"),
New InventoryItem(1, 200, "Professional Isolation Headphones"),
New InventoryItem(1, 100, "Caviar (Does this Need to Be Refrigerated?)")
}
' Function to simulate retrieval from DataBase
Protected Function GetData( _
ByVal weight As Integer,
ByVal cost As INteger
) As IEnumerable(Of InventoryItem)
' Example of LINQ can be found here
' http://msdn.microsoft.com/en-us/vstudio/bb688088.aspx
' I believe LINQ is the way of the future
Dim returnValue As IEnumerable(Of InventoryItem) =
From items In storeItems
Where (items.weight >= weight) AndAlso (items.cost >= cost)
Select items
Return returnValue
End Function
' CreativeInCode's STuff starts here
Protected Sub Me_Load(ByVal sender As Object, ByVal e As EventArgs) _
Handles Me.Load
End Sub
Protected Sub BtnGetData_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles BtnGetData.Click
Dim ddlFirstValue As Integer = DropDownListOne.SelectedValue
Dim ddlSecondValue As Integer = DropDownListSecond.SelectedValue
MyGridView.DataSource = GetData(ddlFirstValue, ddlSecondValue)
myGridView.DataBind()
End Sub
''' <summary>
''' Made some modifications to CreativeInCode's function to
''' dump the output to the user
''' </summary>
Protected Sub BtnSubmit_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles BtnSubmit.Click
Dim outputToUser As String = _
"The user put the following values in the GridView:<br />"
For Each row As GridViewRow In MyGridView.Rows 'this returning 0 rows
'Do something
' This is just here to make a good place to set a
' breakpoint
Dim weightStr As String = row.Cells(0).Text
Dim costStr As String = row.Cells(1).Text
Dim tbDescription As TextBox = row.FindControl("descId")
Dim description As String = tbDescription.Text
outputToUser &=
String.Format(
"weight={0}, cost={1}, description={2}<br />", _
weightStr, _
costStr, _
description
)
Next
' Show the user the changes she/he made to the GridView
theLiteral.Text = outputToUser
End Sub
End Class