好的。我长期以来一直将此站点用作参考，但现在我遇到了自己的问题。
我正在创建一个继承自 System.Web.UI.WebControls.GridView 类的自定义服务器控件。它的目的只是显示具有非常明确的格式的网格。它可以很好地绑定和加载数据，但尝试激活任何分页都会引发异常，提示“找到具有相同 ID 'lblHdrText_2' 的多个控件。FindControl 要求控件具有唯一 ID。”。
我可以将事件扔给用户并让他们进行分页，但目标之一是让该控件能够处理自己的分页，就像 GridView 控件已经做的那样。
我在排序和更改页面大小时也遇到了同样的问题。基本上任何时候我在控件中调用“DataBind”之后它已经被渲染。
以下是处理这些事件的代码：
protected void OnFirstPageClicked(EventArgs e)
{
if (this.FirstPageClicked != null)
this.FirstPageClicked.Invoke(this, e);
GridViewPageEventArgs pgea = new GridViewPageEventArgs(0);
this.OnPageIndexChanging(pgea);
if (pgea.Cancel)
return;
this.PageIndex = 0;
this.RefreshData();
this.OnPageIndexChanged(e);
}
protected void OnLastPageClicked(EventArgs e)
{
if (this.LastPageClicked != null)
this.LastPageClicked.Invoke(this, e);
GridViewPageEventArgs pgea = new GridViewPageEventArgs(this.PageCount - 1);
this.OnPageIndexChanging(pgea);
if (pgea.Cancel)
return;
this.PageIndex = this.PageCount - 1;
this.RefreshData();
this.OnPageIndexChanged(e);
}
protected void OnPreviousPageClicked(EventArgs e)
{
if (this.PageIndex > 0)
{
if (this.PreviousPageClicked != null)
this.PreviousPageClicked.Invoke(this, e);
GridViewPageEventArgs pgea = new GridViewPageEventArgs(this.PageIndex++);
this.OnPageIndexChanging(pgea);
if (pgea.Cancel)
return;
this.PageIndex--;
this.RefreshData();
this.OnPageIndexChanged(e);
}
}
protected void OnNextPageClicked(EventArgs e)
{
if (this.PageIndex < this.PageCount - 1)
{
if (this.NextPageClicked != null)
this.NextPageClicked.Invoke(this, e);
GridViewPageEventArgs pgea = new GridViewPageEventArgs(this.PageIndex++);
this.OnPageIndexChanging(pgea);
if (pgea.Cancel)
return;
this.PageIndex++;
this.RefreshData();
this.OnPageIndexChanged(e);
}
}
protected void OnPageSizeChanged(EventArgs e)
{
this.RefreshData();
if (this.PageSizeChanged != null)
this.PageSizeChanged.Invoke(this, e);
}
protected override void OnDataBound(EventArgs e)
{
base.OnDataBound(e);
}
private void RefreshData()
{
this.DataBind();
}
private void imgPg_OnCommand(object sender, CommandEventArgs e)
{
switch (e.CommandName)
{
case "FirstPage":
this.OnFirstPageClicked(EventArgs.Empty);
break;
case "LastPage":
this.OnLastPageClicked(EventArgs.Empty);
break;
case "PrevPage":
this.OnPreviousPageClicked(EventArgs.Empty);
break;
case "NextPage":
this.OnNextPageClicked(EventArgs.Empty);
break;
}
}
private void drpPageSz_SelectedIndexChanged(object sender, EventArgs e)
{
DropDownList drpPgSz = (sender as DropDownList);
if (drpPgSz != null)
{
this.PageSize = int.Parse(drpPgSz.SelectedValue);
this.OnPageSizeChanged(e);
}
else
throw new Exception("Unable to determine page size: cannot cast sender as DropDownList.");
}
实际的事件处理程序位于底部。“RefreshData”方法就在那里，因为我在调用“DataBind”之前尝试了不同的方法来清除网格中的控件。到目前为止，我尝试过的所有操作都导致整个网格在回发后没有呈现。
我在 Render 和 CreateChildControls 上做了很多工作，但标头生成本身完全是 System.Web.UI.WebControls.GridView 控件的内部。这是我的渲染代码，如果它有帮助的话：
protected override void OnPreRender(EventArgs e)
{
Control link = this.Page.Header.FindControl("CustomGridViewCss");
if (link == null)
{
System.Web.UI.HtmlControls.HtmlLink newLink = new System.Web.UI.HtmlControls.HtmlLink();
newLink.ID = "CustomGridViewCss";
newLink.Attributes.Add("href", this.Page.ClientScript.GetWebResourceUrl(typeof(ITCWebToolkit.Web.UI.Controls.GridView), "ITCWebToolkit.Web.UI.Controls.style.CustomGridView.css"));
newLink.Attributes.Add("type", "text/css");
newLink.Attributes.Add("rel", "stylesheet");
this.Page.Header.Controls.Add(newLink);
}
base.OnPreRender(e);
this.EnsureChildControls();
}
protected override void Render(HtmlTextWriter writer)
{
if (this._imgFPg != null)
this.Page.ClientScript.RegisterForEventValidation(this._imgFPg.UniqueID);
if (this._imgPrevPg != null)
this.Page.ClientScript.RegisterForEventValidation(this._imgPrevPg.UniqueID);
if (this._imgNextPg != null)
this.Page.ClientScript.RegisterForEventValidation(this._imgNextPg.UniqueID);
if (this._imgLastPg != null)
this.Page.ClientScript.RegisterForEventValidation(this._imgLastPg.UniqueID);
if (this._drpPageSz != null)
this.Page.ClientScript.RegisterForEventValidation(this._drpPageSz.UniqueID);
if (this.HeaderRow != null)
for (int i = 1; i < this.HeaderRow.Cells.Count - 2; i++)
if (i < this.Columns.Count && this.Columns[i] is SortableField && ((this.Columns[i] as SortableField).ShowSort))
{
ImageButton img = (this.HeaderRow.Cells[i].FindControl("imgSort_" + i.ToString()) as ImageButton);
if (img != null)
this.Page.ClientScript.RegisterForEventValidation(img.UniqueID);
}
base.Render(writer);
}
protected override Table CreateChildTable()
{
this.PagerSettings.Visible = false;
this.GridLines = GridLines.None;
Table tbl = base.CreateChildTable();
tbl.Attributes.Add("name", this.UniqueID);
return tbl;
}
protected override int CreateChildControls(System.Collections.IEnumerable dataSource, bool dataBinding)
{
this.GridLines = GridLines.None;
int iCount = base.CreateChildControls(dataSource, dataBinding);
// Modify footer row
System.Web.UI.WebControls.GridViewRow ftr = this.FooterRow;
// NOTE: We're modifying the footer first, because we're looking at the
// total number of rows in the header for the ColSpan property we
// use in the footer and we want the row count *before* we modify
// the header.
ftr.Cells.Clear();
this.BuildFooter(this.FooterRow);
// Modify Header Row
System.Web.UI.WebControls.GridViewRow hdr = this.HeaderRow;
hdr.CssClass = "GridViewHeader";
for (int c = 0; c < hdr.Cells.Count; c++)
{
hdr.Cells[c].CssClass = "GridViewHeaderTC";
if (c > 0)
hdr.Cells[c].Style.Add("border-left", "solid 1px #ccccd3");
if (c < this.Columns.Count && this.Columns[c] is SortableField && ((this.Columns[c] as SortableField).ShowSort))
{
hdr.Cells[c].Controls.Clear();
Label lblHdrText = new Label();
lblHdrText.ID = "lblHdrText_" + c.ToString();
lblHdrText.Text = hdr.Cells[c].Text;
hdr.Cells[c].Controls.Add(lblHdrText);
ImageButton imgSort = new ImageButton();
imgSort.ID = "imgSort_" + c.ToString();
imgSort.CssClass = "GridViewHeaderSort";
imgSort.ImageUrl = this.Page.ClientScript.GetWebResourceUrl(typeof(ITCWebToolkit.Web.UI.Controls.GridView), "ITCWebToolkit.Web.UI.Controls.images.gridView.Sort.png");
imgSort.AlternateText = "";
imgSort.CommandArgument = (this.Columns[c] as BoundField).DataField;
imgSort.CommandName = "Sort";
imgSort.Command += new CommandEventHandler(this.imgSort_OnCommand);
hdr.Cells[c].Controls.Add(imgSort);
imgSort.Attributes.Add("name", imgSort.UniqueID);
}
}
TableCell tdTL = new TableCell();
tdTL.Style.Add(HtmlTextWriterStyle.Width, "6px");
tdTL.CssClass = "GridViewHeaderTL";
hdr.Cells.AddAt(0, tdTL);
TableCell tdTR = new TableCell();
tdTR.Style.Add(HtmlTextWriterStyle.Width, "6px");
tdTR.Style.Add("border-left", "1px solid #ccccd3;");
tdTR.CssClass = "GridViewHeaderTR";
hdr.Cells.Add(tdTR);
// Modify individual rows
for (int i = 0; i < this.Rows.Count; i++)
{
System.Web.UI.WebControls.GridViewRow tr = this.Rows[i];
tr.CssClass = (i % 2 == 0) ? "GridViewLineAlt" : "GridViewLine";
for (int c = 0; c < tr.Cells.Count - 1; c++)
tr.Cells[c].Style.Add("border-right", "solid 1px #ccccd3");
TableCell tdL = new TableCell();
tdL.CssClass = "GridViewLineLeft";
tr.Cells.AddAt(0, tdL);
TableCell tdR = new TableCell();
tdR.CssClass = "GridViewLineRight";
tr.Cells.Add(tdR);
}
return iCount;
}
protected void BuildFooter(GridViewRow tr)
{
TableCell tdBL = new TableCell();
tdBL.Style.Add(HtmlTextWriterStyle.Width, "6px");
tdBL.CssClass = "GridViewFooterBL";
tr.Cells.Add(tdBL);
int colCount = this.HeaderRow.Cells.Count;
TableCell td = new TableCell();
td.ID = "tdFooterControls";
td.CssClass = "GridViewFooterBC";
td.ColumnSpan = colCount;
this._spanPgBtns = new Label();
this._spanPgBtns.ID = "spanPgButtons";
this._spanPgBtns.Style.Add("float", "right");
this._spanPgBtns.Style.Add("margin-right", "20px");
this._imgFPg = new ImageButton();
this._imgFPg.ID = "imgFPg";
this._imgFPg.CssClass = "FirstPg";
this._imgFPg.ImageUrl = this.Page.ClientScript.GetWebResourceUrl(typeof(ITCWebToolkit.Web.UI.Controls.GridView), "ITCWebToolkit.Web.UI.Controls.images.gridView.FstPg.png");
this._imgFPg.ImageAlign = ImageAlign.Middle;
this._imgFPg.CommandName = "FirstPage";
this._imgFPg.Command += new CommandEventHandler(this.imgPg_OnCommand);
this._spanPgBtns.Controls.Add(this._imgFPg);
this._imgPrevPg = new ImageButton();
this._imgPrevPg.ID = "imgPrevPg";
this._imgPrevPg.CssClass = "PrevPg";
this._imgPrevPg.ImageUrl = this.Page.ClientScript.GetWebResourceUrl(typeof(ITCWebToolkit.Web.UI.Controls.GridView), "ITCWebToolkit.Web.UI.Controls.images.gridView.PrevPg.png");
this._imgPrevPg.ImageAlign = ImageAlign.Middle;
this._imgPrevPg.CommandName = "PrevPage";
this._imgPrevPg.Command += new CommandEventHandler(this.imgPg_OnCommand);
this._spanPgBtns.Controls.Add(this._imgPrevPg);
Label lblPageNum = new Label();
lblPageNum.ID = "lblPageNum";
lblPageNum.Width = new Unit("50px");
lblPageNum.Text = string.Format("{0} / {1}", this.PageIndex + 1, this.PageCount);
lblPageNum.Style.Add(HtmlTextWriterStyle.TextAlign, "center");
this._spanPgBtns.Controls.Add(lblPageNum);
this._imgNextPg = new ImageButton();
this._imgNextPg.ID = "imgNextPg";
this._imgNextPg.CssClass = "NextPg";
this._imgNextPg.ImageUrl = this.Page.ClientScript.GetWebResourceUrl(typeof(ITCWebToolkit.Web.UI.Controls.GridView), "ITCWebToolkit.Web.UI.Controls.images.gridView.NextPg.png");
this._imgNextPg.ImageAlign = ImageAlign.Middle;
this._imgNextPg.CommandName = "NextPage";
this._imgNextPg.Command += new CommandEventHandler(this.imgPg_OnCommand);
this._spanPgBtns.Controls.Add(this._imgNextPg);
this._imgLastPg = new ImageButton();
this._imgLastPg.ID = "imgLastPg";
this._imgLastPg.CssClass = "LastPg";
this._imgLastPg.ImageUrl = this.Page.ClientScript.GetWebResourceUrl(typeof(ITCWebToolkit.Web.UI.Controls.GridView), "ITCWebToolkit.Web.UI.Controls.images.gridView.LstPg.png");
this._imgLastPg.ImageAlign = ImageAlign.Middle;
this._imgLastPg.CommandName = "LastPage";
this._imgLastPg.Command += new CommandEventHandler(this.imgPg_OnCommand);
this._spanPgBtns.Controls.Add(this._imgLastPg);
td.Controls.Add(this._spanPgBtns);
Label spanPageSz = new Label();
spanPageSz.ID = "spanPageSz";
spanPageSz.Style.Add("margin-left", "20px");
this._drpPageSz = new DropDownList();
this._drpPageSz.ID = "drpPageSzSelect";
this._drpPageSz.AutoPostBack = true;
this._drpPageSz.SelectedIndexChanged += new EventHandler(drpPageSz_SelectedIndexChanged);
this._drpPageSz.Items.Add(new ListItem("10", "10"));
this._drpPageSz.Items.Add(new ListItem("25", "25"));
this._drpPageSz.Items.Add(new ListItem("50", "50"));
this._drpPageSz.Items.Add(new ListItem("100", "100"));
spanPageSz.Controls.Add(this._drpPageSz);
td.Controls.Add(spanPageSz);
Label lblRecVis = new Label();
lblRecVis.ID = "lblRecordsCount";
lblRecVis.Style.Add("margin-left", "20px");
lblRecVis.Text = string.Format("Displaying {0} of {1} records.", Math.Min(this.PageSize, this.Rows.Count - (this.PageIndex * this.PageSize)), this.Rows.Count);
lblRecVis.Text = "Total Record Display";
td.Controls.Add(lblRecVis);
tr.Cells.Add(td);
TableCell tdBR = new TableCell();
tdBR.Style.Add(HtmlTextWriterStyle.Width, "6px");
tdBR.CssClass = "GridViewFooterBR";
tr.Cells.Add(tdBR);
this._imgFPg.Attributes.Add("name", this._imgFPg.UniqueID);
this._imgPrevPg.Attributes.Add("name", this._imgPrevPg.UniqueID);
this._imgNextPg.Attributes.Add("name", this._imgNextPg.UniqueID);
this._imgLastPg.Attributes.Add("name", this._imgLastPg.UniqueID);
this._drpPageSz.Attributes.Add("name", this._drpPageSz.UniqueID);
}
我在自定义服务器控件上只有大约 6/10，所以我确信我在这里至少做错了一件事:)
提前感谢您的帮助！