How to redraw DataGridView from another form

Question

I have a list of items that have a name, price and quantity value. This list is stored in one form, and this form also had an edit button, so that when a user clicks on a row, they are able to edit this item inside another form that pops up.

I have my code working so that the item changes in the list, however it seems like the DataGridView just isn't updating when the list is changed. When I edit an item, and add in a new row, it shows the changed values.

Here is my code for my first form:

private void EditButton_Click(object sender, EventArgs e)
    {
        EditForm editForm = new EditForm();
        if (BasketGrid.RowCount > 0)
        {
            editForm.Show();
        }
    }

So this juts sets up the button so that it shows the other form. "BasketGrid" is my DataGridView, that is also given a public initialization at the beginning of my code (Called dgv)

public void EditOkBut_Click(object sender, EventArgs e)
{
    this.newName = editNameBox.Text;
    decimal price;
    int quant;
    if (decimal.TryParse(editPriceBox.Text, out price))
    {
        this.newPrice = price;
    }
    else
    {
        MessageBox.Show("Incorrect format for price");
    }
    if(int.TryParse(editQuantBox.Text, out quant))
    {
        this.newQuantity = quant;
    }
    else
    {
        MessageBox.Show("Incorrect format for quantity");
    }
    foreach (OrderItem o in basketForm.GetList().ToList())
    {
        string listName = basketForm.getListName();
        if (listName == o.ProductName)
        {
            o.ProductName = this.newName;
            o.ProductPrice = this.newPrice;
            o.ProductQuantity = this.newQuantity;
        }
    }
    this.Close();
}

This is my "Edit Button" in my secondary form. This grabs my itemlist from my other form via a method, and compares the product name in of the orderitem in the list, and the listname that the user has selected from the row.

I'd created 'basketForm' as a new object of my other form, so I can access methods and stuff. I've tried to use basketForm.dgv.Refresh(); but to no avail.

Any help is appreciated.

Cheers, Daniel

Answer 1

You should implement INotifyPropertyChanged interface in the OrderItem class. This will update only one value in DataGridView, instead of updating the entire collection, which may be critical if the collection is very large and its binding may trigger actions, like validation, etc.

class OrderItem : INotifyPropertyChanged
{
    private string name;
    // other fields : price, quantity

    public string Name
    {
        get { return name; }
        set
        {
            if (value != name)
            {
                name = value;
                NotifyPropertyChanged();
            }
        }
    }
    // other properties: Price, Quantity

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Also you have to use BindingList class instead of List. It supports two-way data-binding mechanism.

Answer 2

You can use BindingSource and ShowDialog...

Example:

public partial class MainForm : Form
{
    private BindingSource bindingSource = new BindingSource();

    List<YourData> yourData = new List<YourData>();

    public MainForm()
    {
        InitializeComponent();

        bindingSource.DataSource = yourData;

        dgv.DataSource = bindingSource;
    }
}

Changes will be reflected to your grid like this...

private void EditButton_Click(object sender, EventArgs e)
{
    EditForm editForm = new EditForm(yourData);

    if (BasketGrid.RowCount > 0)
    {
        editForm.ShowDialog(this);

        bindingSource.ResetBindings(true);
    }
}

//Change your Data in EditForm whatever you want
public partial class EditForm : Form
{
    List<YourData> yourData;
    public EditForm(List<YourData> yourData)
    {
        InitializeComponent();
        this.yourData = yourData;
    }
}