GridView column header merging in ASP.NET

adriancs

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13 May 2014Public Domain

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Download DemoMergeGridViewHeader.zip

Screenshot of Merged Headers of a GridView:

Introduction

This is about merging headers of ASP.NET's GridView control.

After I have read the article written by Vinod Viswanath , titled: GridView column header merging in ASP.NET[^]. I am inspired/learned by his work. Therefore, I would like to present another sample demo based on some of his concept.

Walkthrough

In this example, I am coloring the GridView using CSS. This is the definition of the CSS used in this example:

CSS

body {
    font-family: 'Segoe UI', Helvetica, Arial;
    font-size: 10pt;
}
table {
    border-collapse: collapse;
}
td {
    padding: 5px;
    border: 1px solid black;
    text-align: center;
}
.Day {
    background-color: #9b87ff;
    color: white;
    border: 1px solid black;
    padding: 5px;
}
.Car {
    background-color: #ffb4f7;
    color: #a30095;
    border: 1px solid black;
    padding: 5px;
}
.Bus {
    background-color: yellow;
    color: #ff6a00;
    border: 1px solid black;
    padding: 5px;
}
.Taxi {
    background-color: #b6ff00;
    color: #5a8a00;
    border: 1px solid black;
    padding: 5px;
}
tr:nth-child(odd) {
    background-color: #fffbb7;
}
tr:nth-child(even) {
    background-color: #dddddd;
}

Adding a GridView into the WebForm as usual:

ASP.NET

 <%@ Page Language="C#" AutoEventWireup="true"
    CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1"
     ViewStateMode="Disabled" EnableViewState="false" %>

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" ></asp:GridView>
    </div>
    </form>
</body>
</html>

Code behind, at Page_Load block, bind a DataTable to GridView as usual:

protected void Page_Load(object sender, EventArgs e)
{
    GridView1.RowCreated += GridView1_RowCreated;

    DataTable dt = new DataTable();

    for (int i = 0; i < 9; i++)
    {
        dt.Columns.Add("dt" + (i + 1));
    }

    for (int i = 0; i < 10; i++)
        dt.Rows.Add(1, 2, 3, 4, 5, 6, 7, 8, 9);

    GridView1.DataSource = dt;
    GridView1.DataBind();
}

During the Header Row is created, we manually define the Merged Header here:

void GridView1_RowCreated(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.Header)
    {
        e.Row.Visible = false;

        AddHeaderRow1();
        AddHeaderRow2();
    }
}

First row contains Header Cells which span to 3 columns, and at the same time, we assign the CSS class definition here:

void AddHeaderRow1()
{
    GridViewRow gr = new GridViewRow(0, 0, DataControlRowType.Header, DataControlRowState.Insert);

    TableHeaderCell thc1 = new TableHeaderCell();
    TableHeaderCell thc2 = new TableHeaderCell();
    TableHeaderCell thc3 = new TableHeaderCell();

    thc1.Text = "Day 1";
    thc2.Text = "Day 2";
    thc3.Text = "Day 3";

    thc1.ColumnSpan = 3;
    thc2.ColumnSpan = 3;
    thc3.ColumnSpan = 3;

    // Assign CSS
    thc1.CssClass = "Day";
    thc2.CssClass = "Day";
    thc3.CssClass = "Day";

    gr.Cells.AddRange(new TableCell[] { thc1, thc2, thc3 });

    GridView1.Controls[0].Controls.AddAt(0, gr);
}

Next, the second Header Row:

void AddHeaderRow2()
{
    GridViewRow gr = new GridViewRow(0, 0, DataControlRowType.Header, DataControlRowState.Insert);

    TableHeaderCell thc1 = new TableHeaderCell();
    TableHeaderCell thc2 = new TableHeaderCell();
    TableHeaderCell thc3 = new TableHeaderCell();
    TableHeaderCell thc4 = new TableHeaderCell();
    TableHeaderCell thc5 = new TableHeaderCell();
    TableHeaderCell thc6 = new TableHeaderCell();
    TableHeaderCell thc7 = new TableHeaderCell();
    TableHeaderCell thc8 = new TableHeaderCell();
    TableHeaderCell thc9 = new TableHeaderCell();

    thc1.Text = "Car";
    thc2.Text = "Bus";
    thc3.Text = "Taxi";
    thc4.Text = "Car";
    thc5.Text = "Bus";
    thc6.Text = "Taxi";
    thc7.Text = "Car";
    thc8.Text = "Bus";
    thc9.Text = "Taxi";

    // Assign CSS
    thc1.CssClass = "Car";
    thc2.CssClass = "Bus";
    thc3.CssClass = "Taxi";
    thc4.CssClass = "Car";
    thc5.CssClass = "Bus";
    thc6.CssClass = "Taxi";
    thc7.CssClass = "Car";
    thc8.CssClass = "Bus";
    thc9.CssClass = "Taxi";

    gr.Cells.AddRange(new TableCell[] { thc1, thc2, thc3, thc4, thc5, thc6, thc7, thc8, thc9 });

    GridView1.Controls[0].Controls.AddAt(1, gr);
}

Done. You have a GridView with headers merged.

Happy coding :)

License

This article, along with any associated source code and files, is licensed under A Public Domain dedication

Written By

adriancs

Software Developer

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GridView column header merging in ASP.NET

Introduction

Walkthrough

License

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