ASP.NET - C# Retrieve DataGrid Cell via HeaderText

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Introduction

In the previous article, Hide DataGrid Columns via HeaderText, I described how to hide a DataGridColumn via the HeaderText. If you have not read the previous article, it provides a method to hide/show columns based on a user's view. This solved the problem of referencing the index of the column which can lead to problems when you move columns around. This article is built upon that example and demonstrates how to retrieve data in the DataGrid by the column's HeaderText. You will now have the ability to use the text of the header for both populating and retrieving data from the DataGrid.

I ran into the problem of referencing the index of a column a while back. As you know, users frequently want to add, remove, and move columns in a grid. This can become a tedious task if you have many columns in the grid. There is a simple solution to the indexing nightmare. For the simplicity of the example, I opted to include the methods that retrieve a cell or column by HeaderText in the page's class. In your application, you could choose to create a custom DataGrid and implement the methods in it, or create a helper class that each grid will call, or just do what I did.

The code

Below is an example of the method that retrieves a TableCell by the headerText. The input parameters are DataGridItem item and string headerText. To use this method, you would loop through the DataGridItems, which I will show you how to do:

public TableCell GetCellByHeaderText(DataGridItem item, 
                                       string headerText)
{
    if(item == null || headerText == null)
    {
        return null;
    }

    DataGrid dg = item.NamingContainer as DataGrid;
    int colNum = this.GetIndexByHeaderText(dg.Columns, 
                                           headerText);

    if(colNum >= 0)
    {
        return item.Cells[colNum];
    }
    // No cell found by header text.
    return null;
}

This method retrieves a DataGridColumn by the headerText. The input parameters are DataGrid dg and string headerText:

public DataGridColumn GetColumnByHeaderText(DataGrid dg, 
                                        string headerText)
{
    if(dg == null || dg.Columns == null || 
                                  headerText == null)
    {
        return null;
    }
    // Loop through each column in the grid.
    foreach(DataGridColumn col in dg.Columns)
    {
        if(col.HeaderText == headerText)
        {
            return col;
        }
    }
    // No column found by header text.
    return null;
}

This method retrieves the index of the column where the column's HeaderText matches the passed in headerText. The input parameters are DataGridColumnCollection cols and string headerText:

private int GetIndexByHeaderText(DataGridColumnCollection cols, 
                                                string headerText)
{
    if(cols == null)
    {
        return -1;
    }
    // Loop through each column in the grid.
    for(int i=0; i < cols.Count; i++)
    {
        if(cols[i].HeaderText == headerText)
        {
            return i;
        }
    }
    // No column found by header text.
    return -1;
}

Page code-behind

This method utilizes the methods shown above to retrieve the data via the HeaderText. It is placed in the page's code-behind class. The method loops through each DataGridItem in the DataGrid. This example outputs the data back on the page for demonstration purposes. In a real application, you would store the data in a database.

private void DisplayDataFromGrid()
{
    
    // Loop through the items in the grid.
    foreach(DataGridItem item in this.dgExample2.Items)
    {
        string name = this.GetCellByHeaderText(item, 
                                          "Name").Text;
        string title = this.GetCellByHeaderText(item, 
                                         "Title").Text;
        string phone = this.GetCellByHeaderText(item, 
                                         "Phone").Text;
        string email = this.GetCellByHeaderText(item, 
                                         "Email").Text;
        string salary = this.GetCellByHeaderText(item, 
                                         "Salary").Text;
        string ssnum = this.GetCellByHeaderText(item, 
                                         "SS#").Text;
        
        // Write to screen - for testing only...
        Response.Write(name);
        Response.Write(" | " + title);
        Response.Write(" | " + phone);
        Response.Write(" | " + email);
        Response.Write(" | " + salary);
        Response.Write(" | " + ssnum);
        Response.Write("<br>");
    }
}

Conclusion

By using this article's and my previous article's examples, you no longer need to reference a column by the index. You can use the HeaderText for both display and retrieval purposes. This can save you a great amount of time if your DataGrid is constantly modified.