更新 DataGridView 中的单元格，否则创建新行

Question

I have two DataGridView Tables. One contains all the products and quantity available MO_CatData

The second is the items you add to the table. MO_quantityData

Now, if I choose a selected row from MO_CatData and click Add to Order it should loop through MO_quantityData . If the Product ID is already inside the table then we just update the quantity; Else we make a new Row.

So to get the product ID in the MO_CatData I've used:

int id = Convert.ToInt32(MO_CatData.SelectedRows[0].Cells[0].Value);

Then I want to use a for loop and check whether it exists; if it does it'll update otherwise create a new row:

else
{
    int id = Convert.ToInt32(MO_CatData.SelectedRows[0].Cells[0].Value);
    for (int i = 0; i < MO_quantityData.Rows.Count; i++)
    {
        Debug.WriteLine(id);

        if (Convert.ToInt32(MO_quantityData.Rows[i].Cells[2].Value) == id)
        {
            Debug.WriteLine("Gets to if");
            qty = Convert.ToInt32(MO_quantity.Text);
            int newQty = Convert.ToInt32(MO_quantityData.Rows[i].Cells[3].Value) + qty;
            table.Rows[i][3] = newQty;

            float totalprice = newQty * price;
            totalPrice = totalprice;
            sum += totalPrice;

            table.Rows[i][5] = totalPrice;
            MO_quantityData.DataSource = table;
            MO_CatData.Refresh();
        }
        else
        {
            Debug.WriteLine("ELESLESLELES");
            num = num + 1;

            qty = Convert.ToInt32(MO_quantity.Text);

            float totalprice = qty * price;
            totalPrice = totalprice;

            table.Rows.Add(num, product, prodID, qty, price, totalprice);
            MO_quantityData.DataSource = table;
            MO_CatData.Refresh();

            flag = 0;
            sum += totalPrice;
        }
    }
}

I feel as if my logic is incorrect somewhere because if I try to add 2 Pizza, then 1 Chicken then another pizza I get:

Is using a for statement wrong in this scenario? I thought it would be just as simple as loop through the table, if the increment of the loop, at cell 2 is equal to the selectedRow then update quantity else make a new row but clearly not.

Answer 1

If you break the code up a little, you will probably see what goes wrong: You need to stop the search when you find the right product. I've added a FindRowWithId function that takes care of finding it, and the rest is left as is. You would probably also benefit from only having the price calculations and so on in one place.

private int FindRowWithId(int id)
{
    for (int i = 0; i < MO_quantityData.Rows.Count; i++)
    {
        if (Convert.ToInt32(MO_quantityData.Rows[i].Cells[2].Value) == id)
        {
            return i;
        }
    }
    return -1; // Not found;
}

...
else
{
    int id = Convert.ToInt32(MO_CatData.SelectedRows[0].Cells[0].Value);
    int foundRow = FindRowWithId(id);
    if (foundRow > -1)
    {
        Debug.WriteLine("Gets to if");
        qty = Convert.ToInt32(MO_quantity.Text);
        int newQty = Convert.ToInt32(MO_quantityData.Rows[foundRow].Cells[3].Value) + qty;
        table.Rows[foundRow][3] = newQty;
        float totalprice = newQty * price;
        totalPrice = totalprice;
        sum += totalPrice;

        table.Rows[foundRow][5] = totalPrice;
        MO_quantityData.DataSource = table;
        MO_CatData.Refresh();
    }
    else
    {
        Debug.WriteLine("ELESLESLELES");
        num = num + 1;

        qty = Convert.ToInt32(MO_quantity.Text);

        float totalprice = qty * price;
        totalPrice = totalprice;

        table.Rows.Add(num, product, prodID, qty, price, totalprice);
        MO_quantityData.DataSource = table;
        MO_CatData.Refresh();

        flag = 0;
        sum += totalPrice;
    }
}