我在向GridView动态添加列时遇到问题。我需要根据DropDownList中的值更改布局 - 即包含的列。当用户更改此列表中的选择时，我需要删除除第一列之外的所有列，并根据选择动态添加其他列。
我的标记中只定义了一个列 - 第0列，一个模板列，其中我声明了一个Select链接和另一个特定于应用程序的LinkButton。该专栏需要始终存在。在创建ListBoxSelection时，我删除除第一列之外的所有列，然后重新添加所需的列（在此示例中，我将其简化为始终添加“标题”列）。以下是代码的一部分：
RemoveVariableColumnsFromGrid();
BoundField b = new BoundField();
b.DataField = "Title";
this.gvPrimaryListView.Columns.Add(b);
this.gvPrimaryListView.DataBind();
private void RemoveVariableColumnsFromGrid() {
int ColCount = this.gvPrimaryListView.Columns.Count;
//Leave column 0 -- our select and view template column
while (ColCount > 1) {
this.gvPrimaryListView.Columns.RemoveAt(ColCount - 1);
--ColCount;
}
}
第一次运行此代码时，我会看到静态列和动态添加的“标题”列。但是，下次进行选择时，第一列将生成为空（其中没有任何内容）。我看到了标题栏，我看到它左边的第一列 - 但是里面没有生成任何内容。在调试器中，我可以看到gvPrimaryListView确实仍然有两列，第一列（索引0）确实是一个模板列。事实上，该列甚至保留了它的宽度，在下面的标记中设置为165px（用于调试目的）。
有什么想法吗？
<asp:GridView ID="gvPrimaryListView" runat="server" Width="100%" AutoGenerateColumns="false"
DataKeyNames="Document_ID" EnableViewState="true" DataSourceID="odsPrimaryDataSource"
AllowPaging="true" AllowSorting="true" PageSize="10" OnPageIndexChanging="activeListView_PageIndexChanging"
AutoGenerateSelectButton="False" OnSelectedIndexChanged="activeListView_SelectedIndexChanged"
Visible="true" OnRowDataBound="CtlDocList_RowDataBound" Font-Size="8pt" Font-Names="Helvetica">
<Columns>
<asp:TemplateField ShowHeader="false">
<ItemTemplate>
<asp:LinkButton EnableTheming="false" ID="CtlSelectDocRowBtn" runat="server" Text="Select"
CommandName="Select" CssClass="gridbutton" OnClick="RowSelectBtn_Click" />
<asp:ImageButton EnableTheming="false" ID="DocViewBtn" runat="server" ImageUrl="../../images/ViewDoc3.png"
CssClass="gridbutton" CommandName="Select" OnClick="DocViewBtn_Click" />
</ItemTemplate>
<ItemStyle Width="165px" />
</asp:TemplateField>
</Columns>
<EmptyDataTemplate>
<asp:Label ID="Label6" runat="server" Text="No rows found." SkinID="LabelHeader"></asp:Label>
</EmptyDataTemplate>
</asp:GridView>
只是一些额外的信息。
这与它是第一列这一事实无关，而是与它是一个TemplateField这一事实有关。如果我将一个普通列放在左侧（在标记中）并将TemplateField列向右移动，则第一列呈现正常，而（现在第二列）TemplateField列将消失。
另一个奇怪的事情 - 问题不会发生在第一次回发 - 或第二次 - 但它从第三次回发开始，然后继续进行后续回发。我很难过。
答案 0 :(得分：5)
我最近在gridviews中用动态列征服了silmilar问题，也许这会有所帮助。
首先关闭视图状态 其次，在oninit事件中触发的函数中以编程方式添加列 最后，我使用以下帮助程序类使复选框在RowDataBound事件启动时实例化。是的，其中一些是硬编码的。
这里是所有代码。拥有它:)保持原样，等等等等......
最后，因为我只是弄湿了DotNet任何提示都会受到赞赏[IE不要扯我太多:)]。是的，从网上“借用”了初始代码，对不起，我不记得我的头脑:(
- 在受保护的覆盖void OnInit
中将其关闭 private void GridViewProject_AddColumns()
{
DataSet dsDataSet = new DataSet();
TemplateField templateField = null;
try
{
StoredProcedure sp = new StoredProcedure("ExpenseReportItemType_GetList", "INTRANETWEBDB", Context.User.Identity.Name);
dsDataSet = sp.GetDataSet();
if (sp.RC != 0 && sp.RC != 3000)
{
labelMessage.Text = sp.ErrorMessage;
}
int iIndex = 0;
int iCount = dsDataSet.Tables[0].Rows.Count;
string strCategoryID = "";
string strCategoryName = "";
iStaticColumnCount = GridViewProject.Columns.Count;
// Insert all columns immediatly to the left of the LAST column
while (iIndex < iCount)
{
strCategoryName = dsDataSet.Tables[0].Rows[iIndex]["CategoryName"].ToString();
strCategoryID = dsDataSet.Tables[0].Rows[iIndex]["CategoryID"].ToString();
templateField = new TemplateField();
templateField.HeaderTemplate = new GridViewTemplateExternal(DataControlRowType.Header, strCategoryName, strCategoryID);
templateField.ItemTemplate = new GridViewTemplateExternal(DataControlRowType.DataRow, strCategoryName, strCategoryID);
templateField.FooterTemplate = new GridViewTemplateExternal(DataControlRowType.Footer, strCategoryName, strCategoryID);
// Have to decriment iStaticColumnCount to insert dynamic columns BEFORE the edit row
GridViewProject.Columns.Insert((iIndex + (iStaticColumnCount-1)), templateField);
iIndex++;
}
iFinalColumnCount = GridViewProject.Columns.Count;
iERPEditColumnIndex = (iFinalColumnCount - 1); // iIndex is zero based, Count is not
}
catch (Exception exception)
{
labelMessage.Text = exception.Message;
}
}
- 帮手类
public class GridViewTemplateExternal : System.Web.UI.ITemplate
{
#region Fields
public DataControlRowType DataRowType;
private string strCategoryID;
private string strColumnName;
#endregion
#region Constructor
public GridViewTemplateExternal(DataControlRowType type, string ColumnName, string CategoryID)
{
DataRowType = type; // Header, DataRow,
strColumnName = ColumnName; // Header name
strCategoryID = CategoryID;
}
#endregion
#region Methods
public void InstantiateIn(System.Web.UI.Control container)
{
switch (DataRowType)
{
case DataControlRowType.Header:
// build the header for this column
Label labelHeader = new Label();
labelHeader.Text = "<b>" + strColumnName + "</b>";
// All CheckBoxes "Look Up" to the header row for this information
labelHeader.Attributes["ERICategoryID"] = strCategoryID;
labelHeader.Style["writing-mode"] = "tb-rl";
labelHeader.Style["filter"] = "flipv fliph";
container.Controls.Add(labelHeader);
break;
case DataControlRowType.DataRow:
CheckBox checkboxAllowedRow = new CheckBox();
checkboxAllowedRow.Enabled = false;
checkboxAllowedRow.DataBinding += new EventHandler(this.CheckBox_DataBinding);
container.Controls.Add(checkboxAllowedRow);
break;
case DataControlRowType.Footer:
// No data handling for the footer addition row
CheckBox checkboxAllowedFooter = new CheckBox();
container.Controls.Add(checkboxAllowedFooter);
break;
default:
break;
}
}
public void CheckBox_DataBinding(Object sender, EventArgs e)
{
CheckBox checkboxAllowed = (CheckBox)sender;// get the control that raised this event
GridViewRow row = (GridViewRow)checkboxAllowed.NamingContainer;// get the containing row
string RawValue = DataBinder.Eval(row.DataItem, strColumnName).ToString();
if (RawValue.ToUpper() == "TRUE")
{
checkboxAllowed.Checked = true;
}
else
{
checkboxAllowed.Checked = false;
}
}
#endregion
}
答案 1 :(得分：3)
通过以下地址将动态列添加到代码项目的网格视图（ASP）的最佳解决方案： 请检查一下 ： http://www.codeproject.com/Articles/13461/how-to-create-columns-dynamically-in-a-grid-view
答案 2 :(得分：1)
diningphilanderer.myopenid.com与我的推荐方法类似。
问题是每次发生回发时都必须重新绑定网格，因此必须重建列。我喜欢有一个名为BindGrid（）的方法，它首先清除列GridView1.Columns.Clear（）;然后以编程方式添加它们，然后设置数据源并调用数据绑定。确保您为网格禁用了viewstate，并且您有autogeneratecolumns = false;
答案 3 :(得分：1)
我今天早些时候发现了这个：TemplateField in a GridView doesn't have its ViewState restored when BoundFields are inserted。
看起来像Microsoft不打算修复的错误，因此您必须尝试上述解决方案之一。我遇到了同样的问题 - 我有一些DataBoundFields和一些TemplateFields，并且在回发后，基于TemplateField的列会丢失它们的控件和数据。
答案 4 :(得分：1)
我写过一篇关于类似主题的简短文章，该文章基于用户在CheckBoxList控件中选择的列来处理动态填充GridView列。希望这对那些寻求简单演示的人有用How to generate GridView columns dynamically based on user selection?。
答案 5 :(得分：1)
void Page_PreRenderComplete(object sender, EventArgs e)
{
// TemplateField reorder bug: if there is a TemplateField based column (or derived therefrom), GridView may blank out
// the column (plus possibly others) during any postback, if the user has moved it from its original markup position.
// This is probably a viewstate bug, as it happens only if a TemplateField based column has been moved. The workaround is
// to force a databind before each response. See https://connect.microsoft.com/VisualStudio/feedback/details/104994/templatefield-in-a-gridview-doesnt-have-its-viewstate-restored-when-boundfields-are-inserted
//
// This problem is also happening for grid views inside a TabPanel, even if the TemplateField based columns have not
// been moved. Also do a databind in that case.
//
// We also force a databind right after the user has submitted the column chooser dialog.
// (This is because the user could have moved TemplateField based column(s) but ColChooserHasMovedTemplateFields()
// returns false -- ie when the user has moved all TemplateField based columns back to their original positions.
if ((!_DataBindingDone && (ColChooserHasMovedTemplateFields() || _InTabPanel)) || _ColChooserPanelSubmitted || _ColChooserPanelCancelled)
DataBind();
// There is a problem with the GridView in case of custom paging (which is true here) that if we are on the last page,
// and we delete all row(s) of that page, GridView is not aware of the deletion during the subsequent data binding,
// will ask the ODS for the last page of data, and will display a blank. By PreRenderComplete, it will somehow have
// realized that its PageIndex, PageCount, etc. are too big and updated them properly, but this is too late
// as the data binding has already occurred with oudated page variables. So, if we were on the last page just before
// the last data binding (_LastPageIndex == _LastPageCount - 1) and PageIndex was decremented after the data binding,
// we know this scenario has happened and we redo the data binding. See http://scottonwriting.net/sowblog/archive/2006/05/30/163173.aspx
// for a discussion of the problem when the GridView uses the ODS to delete data. The discussion also applies when we
// delete data directly through ClassBuilder objects.
if (_LastPageIndex == _LastPageCount - 1 && PageIndex < _LastPageIndex)
DataBind();
if (EnableColChooser)
{
if (!_IsColChooserApplied)
ApplyColChooser(null, false, false);
else
{
// The purpose of calling ApplyColChooser() here is to order the column headers properly. The GridView
// at this point will have reverted the column headers to their original order regardless of ViewState,
// so we need to apply our own ordering. (This is not true of data cells, so we don't have to apply
// ordering to them, as reflected by the parameters of the call.)
// If we have already processed column reordering upon the column chooser panel being submitted,
// don't repeat the operation.
if (!_ColChooserPanelSubmitted)
ApplyColChooser(null, false, true);
}
}
}
答案 6 :(得分：0)
我在文档中的DataControlFieldCollection类下找到了这个小块。
如果您使用的是GridView或DetailsView控件，则自动创建的DataControlField对象（例如，当AutoGenerateColumns属性为true时）不会存储在可公开访问的字段集合中。您只能访问和操作未自动生成的DataControlField对象。
我想答案是在代码中进行所有列操作，然后你的方法应该可以正常工作。
答案 7 :(得分：0)
不是动态添加列，而是可以在开始时定义它们并根据需要隐藏/显示它们（使用Visible =“false”或将控件/页眉/页脚的CssClass设置为具有“display：none”的类;“）？我在我的一些代码中使用此方法，包括模板列，没有任何问题。
答案 8 :(得分：0)
如果这仍然是一个问题，我想知道你的项目模板中有什么不同？如果您只是在其中放入一些文本，那么刷新页面几次，文本是否出现在第一次加载，然后不出现在第二次？
此外，当出现问题时，单元格中是否存在任何html标记，或者它们是否完全为空？