Schaltfläche Click-Ereignis verhindern, fügt Zeile unter der Bedingung zur Listenansicht

Question

Ich bin neu zu XAML und C# Wie kann ich meine Schaltfläche Click-Ereignis verhindern, dass eine neue Zeile hinzugefügt bereits zur Listenansicht, wenn die ProductID

existiert

private void btnAddToOrder_Click(object sender, RoutedEventArgs e) 
{ 
    //addtoorders 
    if (listStocks.SelectedIndex >= 0) 
    { 
     DataRowView row = (DataRowView)listStocks.SelectedItems[0]; 

     List<Orders> orders = new List<Orders>(); 
     orders.Add(new Orders() 
     { 
      ProductID = row["productID"].ToString(), 
      ProductName = row["productName"].ToString(), 
      Price = Convert.ToDouble(row["sellingPrice"]), 
      Quantity = Convert.ToInt32(row["quantity"]) 

     }); 
     listOrders.Items.Add(orders); 
     } 
} 

Answer 1

Warum zuerst ein neues Objekt von Orders erstellen?

können Sie LINQ verwenden, die

using System.Linq; 

erfordert und dann

var found = ordersobject.FirstOrDefault(x => x.Contains(row["productID"].ToString())); //Replace ordersobject with the Orders object that you have created 

mit

Schließlich, wenn var das Produkt also kehrt null fügen Sie dann gefunden,

private void btnAddToOrder_Click(object sender, RoutedEventArgs e) 
{ 
    //addtoorders 
    if (listStocks.SelectedIndex >= 0) 
    { 

    DataRowView row = (DataRowView)listStocks.SelectedItems[0]; 

    var found = ordersobject.FirstOrDefault(x=>x.Contains(row["productID"].ToString())); 


     if(found == null) 
     { 
      //According to my knowledge a new object i.e., 
      //List<Orders> orders = new List<Orders>(); doesn't have to be defined below 
      //provided that you have defined an object of class Orders before, 
      //unless you want to create various objects of Orders. 
      //Which will cause a lot of trouble in future. 
      List<Orders> orders = new List<Orders>(); 
      orders.Add(new Orders() 
      { 
       ProductID = row["productID"].ToString(), 
       ProductName = row["productName"].ToString(), 
       Price = Convert.ToDouble(row["sellingPrice"]), 
       Quantity = Convert.ToInt32(row["quantity"]) 

      }); 
      listOrders.Items.Add(orders); 
      } 
     } 
    } 
} 

Answer 2

glaube ich diesen Code kann Ihnen helfen:

private void btnAddToOrder_Click(object sender, RoutedEventArgs e) 
{ 
    //addtoorders 
    if (listStocks.SelectedIndex >= 0) 
    { 
     DataRowView row = (DataRowView)listStocks.SelectedItems[0]; 
     Orders o=(Orders)row; 
     List<Orders> orderlist=(List<Orders>)listOrders.ItemsSource; 
     if(orderlist.Find(x=>x.PRoductID==c1.PRoductID)!=null) 
     { 
      MessageBox.Show("This Product already exists!"); 
     } 
     else 
     { 
      listOrders.Items.Add(orders); 
     } 

    } 

}

Answer 3

private void btnAddToOrder_Click(object sender, RoutedEventArgs e) 
    { 


     //addtoorders 
     if (listStocks.SelectedIndex >= 0) 
     { 
      DataRowView row = (DataRowView)listStocks.SelectedItems[0]; 

      Orders newOrder = new Orders() 
      { 
       ProductID = row["productID"].ToString(), 
       ProductName = row["productName"].ToString(), 
       Price = Convert.ToDouble(row["sellingPrice"]), 
       Quantity = Convert.ToInt32(row["quantity"]) 

      }; 
      List<Orders> orders = new List<Orders>(); 
      // 
      bool found = false; 
      foreach(Orders order in orders) 
      { 
       if (order.Equals(newOrder)) 
       { 
        //if Found Order Equal NewOrder 
        found = true; 
        break; 
       } 
      } 
      if(found == true) 
      { 
       Console.WriteLine("We are Found Order = NewOrder"); 
       return; //Exit From Method 
      } 
      //If Found == false 
      orders.Add(newOrder); 
      listOrders.Items.Add(orders); 
     } 
    }