How to merge cells with equal values in a GridView

Download sample code - 3.25 KB

Introduction

There are a lot of methods in the Internet solving the problem of how to merge GridView rows if neighboring cells show equal values. My approach is not the first; however, I think, it is rather universal and very short - less than 20 lines of code.

The algorithm is simple: to bypass all the rows, starting from the second at the bottom, to the top. If a cell value is the same as a value in the previous (lower) row, then increase RowSpan and make the lower cell invisible, and so forth.

The code that merges the cells is very short:

public class GridDecorator
{
    public static void MergeRows(GridView gridView)
    {
        for (int rowIndex = gridView.Rows.Count - 2; rowIndex >= 0; rowIndex--)
        {
            GridViewRow row = gridView.Rows[rowIndex];
            GridViewRow previousRow = gridView.Rows[rowIndex + 1];

            for (int i = 0; i < row.Cells.Count; i++)
            {
                if (row.Cells[i].Text == previousRow.Cells[i].Text)
                {
                    row.Cells[i].RowSpan = previousRow.Cells[i].RowSpan < 2 ? 2 : 
                                           previousRow.Cells[i].RowSpan + 1;
                    previousRow.Cells[i].Visible = false;
                }
            }
        }
    }
}

The last action is to add an OnPreRender event handler for the GridView:

protected void gridView_PreRender(object sender, EventArgs e)
{
    GridDecorator.MergeRows(gridView);
}

This is a cross-post from my personal blog...

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Mykola Tarasyuk

Web Developer

Ukraine

Member

I am a software developer from Ukraine. In my spare time, I am blogging about ASP.Net and web development.

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Good One

Dorababu743

0:25 16 Jan '12

Hi Mykola good article, I am having a question if i would like to merge the first cell instead of all what should I do..
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Re: Good One

Mykola Tarasyuk

0:52 16 Jan '12

Not sure that I understand your needs. Could you please post a sample of what you are trying to achieve?
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Re: Good One

Dorababu743

1:03 16 Jan '12

Instead of merging each and every cell if I would like to merge only first cell, how can I do this..
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Re: Good One

Mykola Tarasyuk

4:47 16 Jan '12

>> to merge only first cell What does it mean "to merge only first cell"? How can you merge single cell? Does it mean merging cells in the first column? Could you be more concrete?
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Re: Good One

Dorababu743

4:49 16 Jan '12

Yeah i would like to merge only Manufacturer if duplicate exists
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Re: Good One

Mykola Tarasyuk

5:32 16 Jan '12

try to change

            for (int i = 0; i < row.Cells.Count; i++)
            {
                if (row.Cells[i].Text == previousRow.Cells[i].Text)
                {
                    row.Cells[i].RowSpan = previousRow.Cells[i].RowSpan < 2 ? 2 :
                                           previousRow.Cells[i].RowSpan + 1;
                    previousRow.Cells[i].Visible = false;
                }
            }

                           
                if (row.Cells[0].Text == previousRow.Cells[0].Text)
                {
                    row.Cells[0].RowSpan = previousRow.Cells[0].RowSpan < 2 ? 2 :
                                           previousRow.Cells[0].RowSpan + 1;
                    previousRow.Cells[0].Visible = false;
                }

Re: Good One

Dorababu743

6:12 16 Jan '12

Thanks Mykola
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My vote of 5

Dorababu743

23:51 15 Jan '12

Good one
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My vote of 5

ramakrishnankt

0:22 22 Dec '11

Really useful, I used this in my project
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have 5

Pranay Rana

22:41 16 Jan '11

nice piece of code My blog:http://pranayamr.blogspot.com/ Programming practice Do vote my articles December 2010 Best C# article of Best ASP.NET article of Best overall artic
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My vote of 5

vhkvemuri

4:20 19 Nov '10

Simple and Elegant. Very Nice
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merge cells in Windows Application Using WPF DataGrid.

tripathy.rajendra@gmail.com

21:35 28 Sep '10

Hi. your Application is too good. but I want to do it in Windows Application Using WPF DataGrid. Same output i also required. So any help?
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Re: merge cells in Windows Application Using WPF DataGrid.

Mykola Tarasyuk

4:53 29 Sep '10

Sorry, I have never worked with WPF DataGrid. The above approach is based on HTML features and is not suitable for Windows controls.
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Alternating Colors?

cas2000

6:04 19 May '09

First of all, great code!! Is there a way to add alternating colors to each group? Thanks.
Sign In·View Thread·Permalink	5.00/5 (1 vote)

Re: Alternating Colors?

Mykola Tarasyuk

20:48 19 May '09

Hi,

You can do something similar to this (not tested):

if (row.Cells[i].Text == previousRow.Cells[i].Text)
{
       row.Cells[i].RowSpan = previousRow.Cells[i].RowSpan < 2 ? 2 : 
                                           previousRow.Cells[i].RowSpan + 1;
       row.Cells[0].BackColor = System.Drawing.Color.FromArgb(random.Next(int.MaxValue))
       previousRow.Cells[i].Visible = false;
}

where random is an instance of the Random class.

how can this be done for vs2003

iluvtorrent

22:01 15 Apr '09

just wondering how can this be done for vs2003 thx
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Re: how can this be done for vs2003

Mykola Tarasyuk

9:20 16 Apr '09

Replace GridView gridView by DataGrid dataGrid and use dataGrid.Items instead of gridView.Rows. Everything else should work.
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Re: how can this be done for vs2003

iluvtorrent

23:06 16 Apr '09

many thanks. managed to get it to work.
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My vote of 1

keertiraj555

4:30 9 Apr '09

i used the method in my application but i got a problem
Sign In·View Thread·Permalink	1.00/5 (7 votes)

Re: My vote of 1

Mykola Tarasyuk

7:04 9 Apr '09

You gave negative ratings for 5 articles in 20 minutes.[^] It seems that you spend not much time investigating the problem. Have you tried it at all?
Sign In·View Thread·Permalink	5.00/5 (2 votes)

Re: My vote of 1

gstolarov

19:45 9 Apr '09

I suspect he created more then 1 account - I saw other votes at the same time with the same syntax and grammatical errors from the accounts opened today. I also saw something similar happening before

I wish there would be a way to block those guys and remove their voting - they just discourage people who make an effort to share their knowledge.

By the way great article, elegant solutions - thumbs up and 5 from me!

Re: My vote of 1

Mykola Tarasyuk

20:31 9 Apr '09

Thanks for the warm words about my work, the same I can say about yours. Btw, I visited your site. Nice games!
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Re: [SORRY] My vote of 1

keertiraj555

1:09 11 Apr '09

I'm really sorry, i've made a big mistake. Rose | [Rose]

4 from me

gstolarov wrote:
I suspect he created more then 1 account - I saw other votes at the same time with the same syntax and grammatical errors from the accounts opened today. I also saw something similar happening before I wish there would be a way to block those guys and remove their voting - they just discourage people who make an effort to share their knowledge.By the way great article, elegant solutions - thumbs up and 5 from me!

Re: [SORRY] My vote of 1, now 4 from me

keertiraj555

1:25 11 Apr '09

I'm really sorry, i've made a big mistake. Rose | [Rose]

4 from me

gstolarov wrote:
I suspect he created more then 1 account - I saw other votes at the same time with the same syntax and grammatical errors from the accounts opened today. I also saw something similar happening before I wish there would be a way to block those guys and remove their voting - they just discourage people who make an effort to share their knowledge.By the way great article, elegant solutions - thumbs up and 5 from me!

Re: My vote of 1

Shameel

9:31 5 Jul '11

Do not give negative ratings without trying something and without elaborating on what the problem is. Can you take some pains to let us know what is the error that you got?
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