This is my first article in Codeproject. Fortunately I dont have to code the whole process, much of the work has already been done by irwansyah.
All the credits goes to him, he has done a wonderfull job of going through the pain of how the datgrid rendering works. I just studied his code and modified only a few parts so that it can be programmer friendly . So go to the page http://www.codeproject.com/script/Articles/list_articles.asp?userid=191443 and first of all study the whole code and download the files. I will be using those files only.
This refers only to the second datagrid.What I will do is instead of specyfying each cell manually in the page_load method in the WebForm1.aspx.cs, I will use a function ColMerge() to specify only the columns that are needed to merge.I will use only the ASPNetDatagridDecorator.cs file.
First of all I will be modifying the ASPNetDatagridDecorator.cs file. Go to the NewRenderMethod() and delete everything inside it and add the following code.
for (int i = 0; i < ctl.Controls.Count; i++)
TableCell item = (TableCell)asd[i];
i += (item.ColumnSpan-1);
The above code loops through all the default datagrid tablecell controls represented by ctl and renders them. The condition is used to check if a custom table cell has been used or not for having merged datagrid headers.
Then add the following code in an independent part of the file(in the class).
Hashtable asd = new Hashtable();
public void ColMerge(string name, int index,int span)
TableCell cell = new TableCell();
cell.Text = name;
cell.ColumnSpan = span;
cell.HorizontalAlign = HorizontalAlign.Center;
This code had a method which takes the common name of the merged grid header and stores it in the asd hastable to be used in the NewRenderMethod.
No need to modify any thing else in this file.
Now move on to the Webform1.aspx.cs file. In this file under the page-load method write the following code.
private ASPNetDatagridDecorator obj = new ASPNetDatagridDecorator();
TableCell cell = null;
DataGrid1.DataSource = GetData();
obj.DatagridToDecorate = Datagrid2;
obj.ColMerge("Name", 1, 3);
m_add.merge("School", 5, 3);
Datagrid2.DataSource = GetData();
You can add as many ColMerge methods you like in a single datagrid.