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我是 WPF 的新手,并按照此链接使用代码优先方法来构建示例。这个例子有效。 https://msdn.microsoft.com/en-us/data/jj574514.aspx

现在,我正在尝试将其更改为遵循 MVVM。

这是 MainWindow XAML

<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:WPFwithEFSampleCodeFirst" mc:Ignorable="d" x:Class="WPFwithEFSampleCodeFirst.MainWindow"
    Title="MainWindow" Height="352.134" Width="517.53" Loaded="Window_Loaded">

<Grid  Margin="0,0,0,-3">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="0*"/>
        <ColumnDefinition Width="77*"/>
        <ColumnDefinition Width="25*"/>
    </Grid.ColumnDefinitions>
    <Button Content="Save" Grid.Column="2" HorizontalAlignment="Left" Margin="41,167,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>
    <DataGrid Grid.ColumnSpan="2"  ItemsSource="{Binding Categories}" AutoGenerateColumns="False" HorizontalAlignment="Left" Margin="32,10,0,0" VerticalAlignment="Top" Height="124" Width="330" >
        <DataGrid.Columns>
            <DataGridTextColumn  Width="SizeToHeader" Header="Category Id" Binding="{Binding Path = CategoryId}"/>
            <DataGridTextColumn  Width="SizeToHeader" Header="Name" Binding="{Binding Path = Name}"/>
        </DataGrid.Columns>
    </DataGrid>

    <DataGrid Grid.ColumnSpan="2" AutoGenerateColumns="False" HorizontalAlignment="Left" Margin="32,153,0,0" VerticalAlignment="Top" Height="146" Width="330">
        <DataGrid.Columns>
            <DataGridTextColumn  Binding="{Binding CategoryId}" Header="Category Id" Width="SizeToHeader"/>
            <DataGridTextColumn Binding="{Binding Name}" Header="Name" Width="SizeToHeader"/>
            <DataGridTextColumn  Binding="{Binding ProductId}" Header="Product Id" Width="SizeToHeader"/>
        </DataGrid.Columns>
    </DataGrid>
</Grid>

这是 MainWindowViewModel

 class MainWindowViewModel
{
    private ICollectionView _categoryView;

    public ICollectionView Categories
    {
        get { return _categoryView; }
    }

    ProductContext context = new ProductContext();

    public MainWindowViewModel()
    {
        IList<Category> categories = GetCategories();
        _categoryView = CollectionViewSource.GetDefaultView(categories);

    }

    public IList<Category> GetCategories()
    {
        return context.Categories.ToList();
    }
}

我不知道如何将第二个详细信息数据网格绑定到 ViewModel。我希望拥有与原始示例相同的 Master-Details 显示功能。

那么如何将Categories中的Products绑定到第二个datagrid呢?使用 MVVM 实现它的正确方法是什么?


更多信息:

 public class Category
{
    public Category()
    {
        this.Products = new ObservableCollection<Product>();
    }

    public int CategoryId { get; set; }
    public string Name { get; set; }

    public virtual ObservableCollection<Product> Products { get; private set; }
} 

    public class Product
{
    public int ProductId { get; set; }
    public string Name { get; set; }

    public int CategoryId { get; set; }
    public virtual Category Category { get; set; }
} 

    public class ProductContext : DbContext
{
    public DbSet<Category> Categories { get; set; }
    public DbSet<Product> Products { get; set; }
} 
4

3 回答 3

0

最简单的方法是将detail DataGrid的DataContext绑定到主DataGrid的SelectedItem属性

<DataGrid x:Name="MasterGrid" Grid.ColumnSpan="2" ItemsSource="{Binding Categories}" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn  Width="SizeToHeader" Header="Category Id" Binding="{Binding Path = CategoryId}"/>
        <DataGridTextColumn  Width="SizeToHeader" Header="Name" Binding="{Binding Path = Name}"/>
    </DataGrid.Columns>
</DataGrid>

<DataGrid DataContext="{Binding SelectedItem.Products, ElementName=MasterGrid}" Grid.ColumnSpan="2" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn  Binding="{Binding CategoryId}" Header="Category Id" Width="SizeToHeader"/>
        <DataGridTextColumn Binding="{Binding Name}" Header="Name" Width="SizeToHeader"/>
        <DataGridTextColumn  Binding="{Binding ProductId}" Header="Product Id" Width="SizeToHeader"/>
    </DataGrid.Columns>
</DataGrid>
于 2016-04-27T20:35:56.680 回答
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如果不使用ICollectionView它的功能将是一种耻辱......

首先,IsSynchronizedToCurrentItem="true"在您的第一个数据网格(类别)上设置。

然后在您的第二个 DataGrid 中,将 DataSource 与ItemsSource="{Binding Categories.CurrentItem.Products}"Where Categories is your view model绑定ICollectionView

的效果IsSynchToCurrentItem=true是您不需要在视图模型中保存属性来跟踪您当前的项目,因为ICollectionView它会为您完成。

然后每次用户在数据网格中选择一行时,当前项目将在视图模型中更改(并且有一个事件ICollectionView通知)等每次您将在视图模型中设置当前项目时,相应的行将是选择。

除了此功能之外,ICollectionView 使您能够在不触及源集合的情况下进行排序、过滤和分组,最重要的是,它使您能够以编程方式更改视图模型中的当前项目,而不会弄乱 XAML 控件(因此相应的可视化/XAML 项目控件中的选定行)通过使用诸如MoveCurrentTo(object target)MovecurrentToFirst()等方法...。

您的业​​务 C# 模型很好,因此您的 XAML 看起来像这样:

<DataGrid Grid.ColumnSpan="2" IsSynchronizedToCurrentItem="true"  ItemsSource="{Binding Categories}" AutoGenerateColumns="False" HorizontalAlignment="Left" Margin="32,10,0,0" VerticalAlignment="Top" Height="124" Width="330" >
    <DataGrid.Columns>
        <DataGridTextColumn  Width="SizeToHeader" Header="Category Id" Binding="{Binding Path = CategoryId}"/>
        <DataGridTextColumn  Width="SizeToHeader" Header="Name" Binding="{Binding Path = Name}"/>
    </DataGrid.Columns>
</DataGrid>

<DataGrid Grid.ColumnSpan="2" ItemsSource="{Binding Categories.CurrentItem.Products}" AutoGenerateColumns="False" HorizontalAlignment="Left" Margin="32,153,0,0" VerticalAlignment="Top" Height="146" Width="330">
    <DataGrid.Columns>
        <DataGridTextColumn  Binding="{Binding CategoryId}" Header="Category Id" Width="SizeToHeader"/>
        <DataGridTextColumn Binding="{Binding Name}" Header="Name" Width="SizeToHeader"/>
        <DataGridTextColumn  Binding="{Binding ProductId}" Header="Product Id" Width="SizeToHeader"/>
    </DataGrid.Columns>
</DataGrid>
于 2016-08-03T15:25:42.273 回答
0

将主 DataGrid 的 SelectedItem 属性绑定到 ViewModel 中的属性

<DataGrid SelectedItem="{Binding SelectedCategory}" Grid.ColumnSpan="2" ItemsSource="{Binding Categories}" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn  Width="SizeToHeader" Header="Category Id" Binding="{Binding Path = CategoryId}"/>
        <DataGridTextColumn  Width="SizeToHeader" Header="Name" Binding="{Binding Path = Name}"/>
    </DataGrid.Columns>
</DataGrid>

主窗口视图模型

private Category _selectedCategory;

public Category SelectedCategory
{
    get { return _selectedCategory; }
    set
    {
        _selectedCategory = value;
        OnPropertyChanged("SelectedCategory");
        OnPropertyChanged("SelectedCategoryProducts");
    }
}

(这需要您的视图模型实现 INotifyPropertyChanged。OnPropertyChanged 方法调用 PropertyChanged 事件处理程序)

添加另一个返回所选类别的 products 属性的属性

public ObservableCollection<Product> SelectedCategoryProducts
{
    get
    {
        if (_selectedCategory == null) return null;

        return _selectedCategory.Products;
    }
}

将详细信息 DataGrid 绑定到视图模型中的 SelectedCategoryProducts 属性

<DataGrid ItemsSource="{Binding SelectedCategoryProducts}" Grid.ColumnSpan="2" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn  Binding="{Binding CategoryId}" Header="Category Id" Width="SizeToHeader"/>
        <DataGridTextColumn Binding="{Binding Name}" Header="Name" Width="SizeToHeader"/>
        <DataGridTextColumn  Binding="{Binding ProductId}" Header="Product Id" Width="SizeToHeader"/>
    </DataGrid.Columns>
</DataGrid>
于 2016-04-27T23:49:39.570 回答