如何从C＃中的另一种形式刷新Datagrid视图

Question

Firstly i wanna ask about how to refresh the Datagrid View from another form, because in this below codes i can't refresh it from the second form.

This is how i refresh the datagrid view in "Cashier Transaction Form" .

public void loadData()
    {
        var load = (from x in db.tbltransaction
                      join z in db.tblproduct
                      on x.product_ID equals z.ID
                      where x.status.Equals(0)
                      select new
                      {
                          TransactionID = x.belanjaID,
                          ProductID = x.produk_ID,
                          ProductName = z.namaBarang,
                          quantity = x.jumlahBarang,
                          Subtotal = x.subtotal
                      });
        dgvtransaction.DataSource = load;
        dgvtransaction.Columns[0].Visible = false;
    }

nah. what i want to do is when i add the data in 2nd form and i close it (so the event is --> FormClosed on "Cashier Search Product Form" ) can be load "dgvtransaction" in the "Cashier Transaction Form" .

This is the code on the 2nd form so far, to load data on the 1st dgv after closed).

Cashier Transaction Form pk;
    private void Cashier Search Product Form_FormClosed(object sender, FormClosedEventArgs e)
    {
        pk.loadData();
    }

The error is "Object reference not set to an instance of an object."

Thanks for any help.

Answer 1

You're creating a new instance of the parent form, but what you need is to pass in a reference to the original.

public class CashierSearchProductForm
{
    CashierTransactionForm pk;
    public CashierSearchProductForm(CashierTransactionForm pk)
    {
        this.pk = pk;
    }

    private void CashierSearchProduct Form_FormClosed(object sender, FormClosedEventArgs e)
    {
        pk.loadData();
    }

    ...
}

...

var csp = new CashierSearchProductForm(this);

Better yet, just subscribe to the FormClosed event from the original form:

var csp = new CashierSearchProductForm(this);
csp.FormClosed += (s,e) => pk.loadData();