Question

我正致力于在可观察集合中添加和删除行。我有UserControl视图，ListView绑定到ObservableCollection。我还删除了在ViewModel中工作但没有更新UI的命令。

这是我在ViewModel上的代码，它继承自MvvmLight ViewModelBase类。

 public class ProductInfoViewModel : ViewModelBase
{
    #region Properties

    private ObservableCollection<Product> _productList;
    public ObservableCollection<Product> ProductList
    {
        get { return _productList; }
        set
        {
            _productList =  value;
            RaisePropertyChanged("ProductList");
        }
    }

    #endregion
    #region Constructor
    public ProductInfoViewModel()
    {
        ConnectWebService connect = new ConnectWebService();
        string json = connect.getResponse(@"http://localhost:8082/products");
        ProductList = JsonConvert.DeserializeObject<ObservableCollection<Product>>(json);
        DeleteCommand = new RelayCommand<long>((id) => DeleteCommandHandler(id, ProductList));
    }
    #endregion
    #region Commands
    public ICommand DeleteCommand { get; private set; }
    #endregion
    #region CommandsHandlers
    private void DeleteCommandHandler(long id, ObservableCollection<Product> productList)
    {
        try
        {
            productList.Remove(productList.Where(i => i.ProductId == id).First());

        }
        catch (Exception)
        {
        }
    }

这是我在XAML中的代码：

<UserControl.DataContext>
    <local:ProductInfoViewModel/>
</UserControl.DataContext>
<Grid>
    <Grid Margin="0,50,0,100">
        <ListView  Margin="5" SelectionChanged="ListView_SelectionChanged" ItemsSource="{Binding ProductList, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Foreground="Black" Background="White" BorderBrush="{x:Null}" 
                   x:Name="ProductList">
            <ListView.View>
                <GridView>
                    <GridViewColumn  Header="Kod" Width="50" DisplayMemberBinding="{Binding ProductCode}"/>
                    <GridViewColumn  Header="Nazwa" Width="150" DisplayMemberBinding="{Binding ProductName}" />
                    <GridViewColumn  Header="Typ" Width="150" DisplayMemberBinding="{Binding ProductType}" />
                    <GridViewColumn  Header="Opis" Width="300" DisplayMemberBinding="{Binding ProductDescription}" />
                    <GridViewColumn  Header="Dostępność" Width="150" DisplayMemberBinding="{Binding ProductAvability}" />
                    <GridViewColumn Width="80">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <Button Content="Edytuj" Background="Transparent" BorderThickness="0" Foreground="Blue" Width="50" Margin="0" HorizontalAlignment="Center"
                                        Click="Button_Click"/>
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                    <GridViewColumn Width="80">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <Button Content="Usuń" Background="Transparent" BorderThickness="0" Foreground="Blue" Width="50" Margin="0" HorizontalAlignment="Center" 
                                        Click="Delete_Click" Command="{Binding ProductInfoView.DeleteCommand, Mode=OneWay, Source={StaticResource Locator}}" CommandParameter="{Binding ProductId}"
                                         />
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                </GridView>
            </ListView.View>
        </ListView>
    </Grid>

我的产品类实现了INotifyPropertyChanged接口，但我也使用了Fody。

现在，仅当我将视图更改为另一个视图然后返回时，视图才会更新。我无法弄清楚出了什么问题。我将不胜感激任何帮助！

Answer 1

您正在将> lapply(1:3, function(x)grepl("^(NM|GE)|^\\d+,(NM|GE)",gsub('"',"", lyst[[x]]))) [[1]] [1] FALSE TRUE TRUE FALSE TRUE [[2]] [1] FALSE TRUE TRUE FALSE TRUE [[3]] [1] FALSE TRUE TRUE FALSE TRUE的{{1}}属性绑定到Command资源返回的视图模型。您应该将它绑定到Button绑定的同一个实例：

Locator

Answer 2

当您从列表中删除项目时，您不使用产品列表设置器，因此不会调用RaisePropertyChanged。快速解决方法是在删除项目后添加对RaisePropertyChanged的调用：

productList.Remove(productList.Where(i => i.ProductId == id).First());
RaisePropertyChanged("ProductList");

Observable Collection不会更新UI

2 个答案: