WPF DataGrid - 将数据项的属性绑定为 CommandParameter

WPF DataGrid - bind dataitem's property as CommandParameter

提问by Szeki

I recently started to familiarize myself with WPF / MVVM, but I got stuck with bindings. I have an ObservableCollection of Customer objects, I bind this to a DataGrid. What I want to achieve is to bind the item's ID property as a parameter of a Button's command.

我最近开始熟悉 WPF/MVVM，但我被绑定困住了。我有一个客户对象的 ObservableCollection，我将它绑定到 DataGrid。我想要实现的是将项目的 ID 属性绑定为按钮命令的参数。

Here's the relevant code from the CustomerViewModel.cs file

这是 CustomerViewModel.cs 文件中的相关代码

private ObservableCollection<Customer> _customer = new ObservableCollection<Customer>();
public ObservableCollection<Customer> Customers
{
    get
    {
        return _customers;
    }
    set
    {
        SetProperty(ref _customers, value);
    }
}

private ICommand _openCustomerCommand;
public ICommand OpenCustomerCommand
{
    get
    {
        return _openCustomerCommand ?? (_openCustomerCommand = new RelayCommand(param => OpenCustomer((int)param)));
    }
}

and the XAML from CustomerView.xaml:

和来自 CustomerView.xaml 的 XAML：

<DataGrid ItemsSource="{Binding Customers}" >
  <DataGridTemplateColumn Header="Open" Width="Auto">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <Button Content="Open" 
                    Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=DataContext.OpenCustomerViewCommand}"
                    CommandParameter="{Binding Customers/ID}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
  </DataGridTemplateColumn>
</DataGrid>

My problem is the following: according to http://www.wpftutorial.net/BindingExpressions.htmlI can use the forward slash (/) to access the current item of the collection. However, in that case, the received value is null.

我的问题如下：根据http://www.wpftutorial.net/BindingExpressions.html我可以使用正斜杠 (/) 访问集合的当前项目。但是，在这种情况下，接收到的值为空。

I saw Bind CommandParameter to DataItem for a Button in a DataGrid, which suggests to use CommandParameter={Binding}, but then I receive the full object bound to the row, which is okay, but not really what I'm looking for.

我在 DataGrid 中看到Bind CommandParameter to DataItem for a Button，它建议使用 CommandParameter={Binding}，但随后我收到了绑定到该行的完整对象，这很好，但并不是我真正想要的。

回答by Nitin Joshi

If you property name is IDthen just use following

如果您的属性名称是ID那么只需使用以下

<DataGrid ItemsSource="{Binding Customers}" >
  <DataGridTemplateColumn Header="Open" Width="Auto">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <Button Content="Open" 
                    Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=DataContext.OpenCustomerViewCommand}"
                    CommandParameter="{Binding ID}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
  </DataGridTemplateColumn>
</DataGrid>

回答by Szeki

Eventually I figured it out. Despite the mentioned issues, Nitin Joshi's suggestion compiles and works fine in runtime.

最终我想通了。尽管存在上述问题，Nitin Joshi 的建议在运行时编译并运行良好。

However, when I defined the underlying DataType of the collection in the DataTemplate tag, then I got the behavior I expected (e.g. having Intellisense support):

但是，当我在 DataTemplate 标记中定义集合的底层 DataType 时，我得到了我预期的行为（例如，具有 Intellisense 支持）：

<Window x:Class="WPF_Demo.View.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:model="clr-namespace:WPF_Demo.Model"
        Title="MainWindow" Height="300" Width="300"
        DataContext="{StaticResource MainWindowViewModel}"
        >
    <Grid>
        <DataGrid ItemsSource="{Binding Customers}">
            <DataGrid.Columns>
                <DataGridTextColumn Binding="{Binding ID}"></DataGridTextColumn>
                <DataGridTextColumn Binding="{Binding FullName}"></DataGridTextColumn>
                <DataGridTemplateColumn Header="Open" Width="Auto">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate DataType="model:Customer">
                            <Button Content="Open" Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=DataContext.OpenCustomerViewCommand}" CommandParameter="{Binding ID}" />
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>