[Solved] Error: Object reference not set to an instance of an object when DataColumn value is Empty (Null)

When insert empty value from GridView to database error is coming.

Object reference not set to an instance of an object.

ataTable dt = (DataTable)ViewState["dt"];
int codeitem, orderqty;
string ditem;
decimal i_rate;
foreach (DataRow row in dt.Rows)
{ 
    orderqty = int.Parse(row["orderqty"].ToString());
    codeitem = int.Parse(row["Codeitem"].ToString());
    ditem = (row["D_Item"].ToString());
    i_rate = decimal.Parse(row["Item_Rate"].ToString());
    this.InsertRows(codeitem, orderqty, ditem, i_rate);
}

on below line

i_rate = decimal.Parse(row["Item_Rate"].ToString());