我有这个InfiniteScrollCollection列表视图，该列表视图是从Web API获取数据的，并且我有一个onpropertychanged方法，我需要在更改属性时立即使列表视图中的项目更新
public partial class AddOrderPage : ContentPage, INotifyPropertyChanged
{
public InfiniteScrollCollection<Sales_Order_Items> Items { get; }
public AddOrderPage()
{
InitializeComponent();
Items = new InfiniteScrollCollection<Sales_Order_Items>
{
OnLoadMore = async () =>
{
IsBusy = true;
grid.IsVisible = true;
// load the next page
//_dataService.setitemsDB();
var page = Items.Count / PageSize;
// var items = await GetItemsAsync(page, PageSize);
var items = await GetItemsAsync(selectedcategorycode, ++index, searching.Text);
//Console.WriteLine(items);
IsBusy = false;
grid.IsVisible = false;
// return the items that need to be added
return items;
},
OnCanLoadMore = () =>
{
return newfilteredlist.Count > 0;
}
};
}
这是onpropertychanged方法
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
我不熟悉属性更改，因此应该在哪里以及如何调用该函数以立即更新列表视图？
Sales_Order_Items类：
public class Sales_Order_Items
{
public int Id { get; set; }
public string Item_Code { get; set; }
public string description { get; set; }
public string Price_List_Code { get; set; }
public string CURRENCY_CODE { get; set; }
public double price { get; set; }
public string Uom_Code { get; set; }
public string Client_Code { get; set; }
public double return_price { get; set; }
public string Tax_Code { get; set; }
public double Tax { get; set; }
public string CURRENCY_SYMBOL { get; set; }
public double Default_Discount { get; set; }
public int item_order { get; set; }
public int distribution_type { get; set; }
public string Client_Name { get; set; }
public string family { get; set; }
public double converted_price { get; set; }
public double converted_return_price { get; set; }
public double converted_tax { get; set; }
public double converted_discount { get; set; }
public string converted_currency_code { get; set; }
public string converted_currency_symbol { get; set; }
public double stock_quantity { get; set; }
public string expiry_date { get; set; }
public string path { get; set; }
public int requested_quantity { get; set; }
public int displayed_quantity { get; set; }
public float discount { get; set; }
public double totalprice { get; set; }
public double totaldiscount { get; set; }
public double totaltax { get; set; }
public bool is_new { get; set; }
public bool has_promotion { get; set; }
public string last_order_item_date { get; set; }
public string last_order_item_quantity { get; set; }
public bool slashvisivble { get; set; }
public bool discounted { get; set; }
public bool promotioned { get; set; }
public Color promotioncolor { get; set; }
public Color newcolor { get; set; }
public string usercode { get; set; }
public bool istotalprice { get; set; }
public bool isdraft { get; set; }
public Color lineborderitemcolor { get; set; }
}
我的Xaml类：
<ListView x:Name="orderslv" HasUnevenRows="True" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" BackgroundColor="White" SeparatorVisibility="None" Grid.Column="0" Grid.Row="2">
<ListView.Behaviors>
<extended:InfiniteScrollBehavior IsLoadingMore="{Binding isbusy}" />
</ListView.Behaviors>
<ListView.Header>
<StackLayout>
<Label TextColor="#FF0000" IsVisible="False" x:Name="error_label" Text="No items in this category" FontFamily="{StaticResource MyriadProRegularFont}" HorizontalTextAlignment="Center">
<Label.FontSize>
<OnIdiom Phone="20" Tablet="30"/>
</Label.FontSize>
</Label>
</StackLayout>
</ListView.Header>
<ListView.Footer>
<Grid Padding="6" x:Name="grid">
<!-- set the footer to have a zero height when invisible -->
<Grid.Triggers>
<Trigger TargetType="Grid" Property="IsVisible" Value="False">
<Setter Property="HeightRequest" Value="0" />
</Trigger>
</Grid.Triggers>
<!-- the loading content -->
<Label Text="Loading..." TextColor="#039BE5" VerticalOptions="Center" HorizontalOptions="Center" FontFamily="{StaticResource MyriadProSemiBoldFont}">
<Label.FontSize>
<OnIdiom Phone="20" Tablet="30"/>
</Label.FontSize>
</Label>
</Grid>
</ListView.Footer>
<ListView.ItemTemplate>
<DataTemplate>
<customControls:ExtendedViewCell SelectedBackgroundColor="Transparent">
<ViewCell.View>
<controls:CustomStepper Grid.Column="0" Grid.Row="1" HorizontalOptions="CenterAndExpand" OnValueChanged="CustomStepper_OnValueChanged" Text="{Binding requested_quantity }" >
</controls:CustomStepper>
<Frame IsClippedToBounds="True" Padding="0" HasShadow="True" CornerRadius="4" Grid.Column="0" Grid.Row="2">
<Button Text="ADD TO CART" TextColor="#039BE5" BackgroundColor="White" Clicked="Addtocart_Clicked" Padding="5" >
<Button.FontSize>
<OnIdiom Phone="{OnPlatform Android=12,iOS=8}" Tablet="{OnPlatform Android=16,iOS=14}"/>
</Button.FontSize>
<Button.HeightRequest>
<OnIdiom Phone="34" Tablet="40"/>
</Button.HeightRequest>
</Button>
</Frame>
</Grid>
</Grid>
</Grid>
</Frame>
</ViewCell.View>
</customControls:ExtendedViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
当我单击按钮时，我需要立即更新绑定到customstepper文本的“ requested_quantity”属性，我需要您通过该属性的onpropertychanged方法来帮助我，并进行调用以使其更改直接在列表视图上。
预先感谢
答案 0 :(得分：1)
您需要在要更新的对象上实现INotifyPropertyChanged。在这种情况下，似乎您仅在视图模型（针对整个页面）上实现了它。这也非常有用，但是如果要更新Sales_Order_Items，则需要在其上实现接口和方法。
之后，一切应该开始工作。