单击按钮时文本框值未更新

debugcn 发表于 Dev

nivopo_10

好吧，这是我的XAML代码

  <TextBox Grid.Row="2" Grid.Column="1" HorizontalAlignment="Left" VerticalAlignment="Center" Width="25" Margin="100,0,0,0" Height="25" Text="{Binding Quantity, UpdateSourceTrigger=PropertyChanged}"></TextBox>
    <Button Grid.Row="2" Grid.Column="1" HorizontalAlignment="Center" VerticalAlignment="Center" Width="100" Height="25" Content="+" Command="{Binding AddCommand}"></Button>
    <Button Grid.Row="2" Grid.Column="1" HorizontalAlignment="Right" Margin="10" VerticalAlignment="Center" Width="100" Height="25" Content="-" Command="{Binding SubtractCommand}"></Button>

这是我的C＃代码

    public class ViewModel : ObservableObject, INotifyPropertyChanged
{
     private int quantity = 0;
        public int Quantity
        {
            get => quantity;
            set
            {
                if (quantity == value) return;
                quantity = value;
                this.RaisePropertyChangedEvent(nameof(Quantity));
            }
        }
        public ICommand AddCommand => new RelayCommand<string>(
           Add,
           x => true
       );
        public ICommand SubtractCommand => new RelayCommand<string>(
           Sub,
           x => true
       );
        private void Add(string obj)
        {
            quantity += 1;
            Debug.WriteLine(quantity);
        }
        private void Sub(string obj)
        {
            quantity -= 1;
            Debug.WriteLine(quantity);
        }
}

如果按+按钮，数量的值将更改，而-则相同。如果执行Debug.Writeline，则会显示正确的结果。问题是单击按钮时文本框的文本未更新。

肯·塔克

您正在更改不调用RaisePropertyChangedEvent的后备字段的值。将数量更改为数量

    private void Add(string obj)
    {
        Quantity += 1;
        Debug.WriteLine(quantity);
    }
    private void Sub(string obj)
    {
        Quantity -= 1;
        Debug.WriteLine(quantity);
    }

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