How to roll back changes in DataGridView in case of incorrect input

ONLINECAST

3 min read

·

08-10-2024

5

0

Share

When working with a DataGridView in a Windows Forms application, you may encounter situations where users input incorrect data. Handling these situations gracefully is essential for maintaining data integrity and ensuring a smooth user experience. In this article, we will explore how to roll back changes in a DataGridView when invalid input is detected.

Understanding the Problem

The DataGridView control provides a way to display and edit data in a tabular format. However, users may unintentionally enter incorrect data, which can lead to issues in your application. To mitigate this, it's crucial to implement a rollback mechanism that reverts the DataGridView to its previous state when invalid input is detected.

Scenario and Original Code

Let's consider a simple scenario where we have a DataGridView bound to a list of products, with columns for the product name and price. Here's an original code snippet that demonstrates a basic implementation of a DataGridView.

private void InitializeDataGridView()
{
    List<Product> products = new List<Product>
    {
        new Product { Name = "Product1", Price = 10.0 },
        new Product { Name = "Product2", Price = 15.0 }
    };

    dataGridView1.DataSource = products;
}

In this code, we populate the DataGridView with a list of products. However, we have not yet implemented any error handling or rollback mechanism.

Implementing Rollback Mechanism

To allow users to revert changes in the DataGridView when incorrect input is made, we can take the following steps:

1. Store a Copy of the Original Data: Before allowing edits, keep a copy of the original data.
2. Handle the Cell Validating Event: Use the CellValidating event to check for invalid input.
3. Revert Changes: If invalid data is found, reset the DataGridView to the original data.

Here's a modified code example implementing the rollback mechanism:

private List<Product> originalProducts;

private void InitializeDataGridView()
{
    originalProducts = new List<Product>
    {
        new Product { Name = "Product1", Price = 10.0 },
        new Product { Name = "Product2", Price = 15.0 }
    };

    dataGridView1.DataSource = new BindingList<Product>(originalProducts);
    dataGridView1.CellValidating += DataGridView1_CellValidating;
}

private void DataGridView1_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
{
    if (e.ColumnIndex == 1) // Assuming Price is at index 1
    {
        if (!double.TryParse((string)e.FormattedValue, out double result) || result < 0)
        {
            // Input is invalid, cancel edit
            e.Cancel = true;
            MessageBox.Show("Please enter a valid positive number for the price.");
            // Rollback changes
            var currentData = (BindingList<Product>)dataGridView1.DataSource;
            currentData.Clear();
            foreach (var product in originalProducts)
            {
                currentData.Add(product);
            }
        }
    }
}

Key Insights

1. Data Binding: The DataGridView is bound to a BindingList<Product>, which allows for dynamic updates. When we revert the changes, we clear the list and repopulate it with the original data.
2. Input Validation: The CellValidating event checks if the price entered is a valid positive number. If the input fails validation, it cancels the edit and rolls back to the original values.
3. User Experience: Providing feedback through a message box ensures users are aware of their errors, fostering a better user experience.

Additional Best Practices

• Disable Editing Temporarily: You might consider temporarily disabling editing or making fields read-only until the data is validated.
• Provide Clear Error Messages: Use clear, concise error messages that guide users on how to correct their input.
• Log Changes: In complex applications, consider logging changes to allow for auditing and a more robust rollback solution.

Conclusion

Rolling back changes in a DataGridView is vital for managing incorrect user input. By implementing a mechanism that validates data and allows users to revert to previous states, you can significantly improve the reliability and user-friendliness of your application.

References

• Microsoft Docs: DataGridView Control
• Understanding Windows Forms Data Binding

By following this guide, you should be well on your way to implementing an effective rollback mechanism for your DataGridView. Happy coding!