基于bindingcontext删除ListView项

Question

我创建了一个从SQLite DB填充的列表视图.XML看起来像这样:

<ListView x:Name="CalculationListview" ItemsSource="{Binding Calculation}" HasUnevenRows="true">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <StackLayout>
                    <Label Text="{Binding Qty}"></Label>
                    <Label Text="{Binding Note}"></Label>
                    <Button Text="Delete" Clicked="Handle_Clicked"></Button>
                </StackLayout>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

我已经创建了一个按钮,如果单击该按钮,我想从中删除该项目.

我已经从数据库中删除了一个接收给定对象的方法.

public Task<int> DeleteCalculationAsync(Calculation calculation)
{
    return database.DeleteAsync(calculation);
}

不幸的是,我不知道如何从bindingcontext中获取对象,以便我可以删除该项目.我显然已经点击了事件处理程序:

void Handle_Clicked(object sender, System.EventArgs e)
{
    App.Database.DeleteCalculationAsync(SOMETHING HERE);
}

Answer 1

上下文操作

我建议将删除功能移到Context Actions.

当用户长按ViewCell时,当用户在ViewCell上从右向左滑动时,上下文操作将出现在iOS上.

示例截图

此屏幕截图来自Xamarin.Forms文档,并未反映下面的代码.

码

<ListView x:Name="CalculationListview" ItemsSource="{Binding Calculation}" HasUnevenRows="true">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <ViewCell.ContextActions>
                    <MenuItem Text="Delete" IsDestructive="True" Clicked="Handle_Delete"/>
                 </ViewCell.ContextActions>
                <StackLayout>
                    <Label Text="{Binding Qty}"></Label>
                    <Label Text="{Binding Note}"></Label>
                </StackLayout>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

async void Handle_Delete(object sender, System.EventArgs e)
{
    var viewCellSelected = sender as MenuItem;
    var calculationToDelete = viewCellSelected?.BindingContext as Calculation;

    await App.Database.DeleteCalculationAsync(calculationToDelete);
}