Merging columns in GridView/DataGrid header6 Jun 2007
BackgroundAs necessity to show header columns in a few rows occurs fairly often it would be good to have such functionality in the The described below variant of the merging implementation is based on irwansyah‘s idea to use the The code overviewAs it may be required to merge a few groups of columns - for example, 1,2 and 4,5,6 - we need a class to store common information about all united columns. [Serializable] private class MergedColumnsInfo { // indexes of merged columns public List<int> MergedColumns = new List<int>(); // key-value pairs: key = the first column index, value = number of the merged columns public Hashtable StartColumns = new Hashtable(); // key-value pairs: key = the first column index, value = common title of the merged columns public Hashtable Titles = new Hashtable(); //parameters: the merged columns indexes, common title of the merged columns public void AddMergedColumns(int[] columnsIndexes, string title) { MergedColumns.AddRange(columnsIndexes); StartColumns.Add(columnsIndexes[0], columnsIndexes.Length); Titles.Add(columnsIndexes[0], title); } } Attribute
//for GridView <asp:GridView ID="grid" runat=server OnRowCreated="GridView_RowCreated" ... ></asp:GridView> //for DataGrid <asp:DataGrid ID="grid" runat=server OnItemCreated="DataGrid_ItemCreated" ... ></asp:DataGrid> Columns can be defined in design time or can be auto generated - it does not matter and doesn‘t influence the further code. Merging also does not harm sorting and paging if they are used in the GridView/DataGrid.
//property for storing of information about merged columns private MergedColumnsInfo info { get { if (ViewState["info"] == null) ViewState["info"] = new MergedColumnsInfo(); return (MergedColumnsInfo)ViewState["info"]; } } protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { //merge the second, third and fourth columns with common title "Subjects" info.AddMergedColumns(new int[] { 1, 2, 3 }, "Subjects"); grid.DataSource = ... //some data source grid.DataBind(); } } Particular code for GridView: protected void GridView_RowCreated(object sender, GridViewRowEventArgs e)
{
//call the method for custom rendering the columns headers
if (e.Row.RowType == DataControlRowType.Header)
e.Row.SetRenderMethodDelegate(RenderHeader);
}
and for DataGrid: protected void DataGrid_ItemCreated(object sender, DataGridItemEventArgs e)
{
//call the method for custom rendering the columns headers
if (e.Item.ItemType == ListItemType.Header)
e.Item.SetRenderMethodDelegate(RenderHeader);
}
Next code is common for both GridView and DataGrid: //method for rendering the columns headers private void RenderHeader(HtmlTextWriter output, Control container) { for (int i = 0; i < container.Controls.Count; i++) { TableCell cell = (TableCell)container.Controls[i]; //stretch non merged columns for two rows if (!info.MergedColumns.Contains(i)) { cell.Attributes["rowspan"] = "2"; cell.RenderControl(output); } else //render merged columns common title if (info.StartColumns.Contains(i)) { output.Write(string.Format("<td align=‘center‘ colspan=‘{0}‘>{1}</td>", info.StartColumns[i], info.Titles[i])); } } //close the first row output.Write("</tr>"); //set attributes for the second row grid.HeaderStyle.AddAttributesToRender(output); //start the second row output.RenderBeginTag("tr"); //render the second row (only the merged columns) for (int i = 0; i < info.MergedColumns.Count; i++) { TableCell cell = (TableCell)container.Controls[info.MergedColumns[i]]; cell.RenderControl(output); } } That is all. The code can be used without any modification, the only part that has to be changed in a concrete case is: info.AddMergedColumns(new int[] { 1, 2, 3 }, "Foo");
info.AddMergedColumns(new int[] { 6, 7 }, "Bar");
//and so forth ...
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来自: louisasea > 《Develope》