绑定到用户控件中的dependencyproperty，并在嵌套属性更改时调用CanExecute

Question

我创建了一个用户控件，它本质上包含一堆组合框，称为SearchParamsControl。SearchParamsControl包含设置SearchParams类中所有内容所需的所有UI元素：

我的SearchParamsControl:

/// <summary>
/// Interaction logic for SearchParamsControl.xaml
/// </summary>
public partial class SearchParamsControl : INotifyPropertyChanged
{
public SearchParamsControl()
{
InitializeComponent();
}
/// <summary>
/// Radius entries bound to combobox
/// </summary>
public Dictionary<double, string> RadiusEntries
{
get;
set;
} = new Dictionary<double, string>()
{
{0, "This area only" },
{ 0.25, "Within 1/4 mile" },
{ 0.5, "Within 1/2 mile" },
{ 1, "Within 1 mile" },
{ 3, "Within 3 miles" },
{ 5, "Within 5 miles" },
{ 10, "Within 10 miles" },
{ 15, "Within 15 miles" },
{ 20, "Within 20 miles" },
{ 30, "Within 30 miles" },
{ 40, "Within 40 miles" }
};
public Dictionary<PropertyTypeEnum, string> PropertyTypes => PropertyTypeDictionary;
/// <summary>
/// Prices bound to combo box
/// </summary>
public List<int> Prices
{
get;
set;
} = new List<int>()
{
0,
50000,
60000,
70000,
80000,
90000,
100000,
110000,
120000,
125000,
130000,
150000,
200000,
250000,
300000,
325000,
375000,
400000,
425000,
450000,
475000,
500000,
550000,
600000,
650000,
700000,
800000,
900000,
1000000,
1250000,
1500000,
1750000,
2000000,
2500000,
3000000,
4000000,
5000000,
7500000,
10000000,
15000000,
20000000
};
/// <summary>
/// Bedrooms bound to combobox
/// </summary>
public List<int> Bedrooms
{
get;
set;
} = new List<int>()
{
0,
1,
2,
3,
4,
5
};
public StringTrieSet SearchString
{
get
{
return RightMoveCodes.RegionTree;
}
}
public double Radius
{
get => SearchParams.Radius;
set
{
if (SearchParams.Radius != value)
{
SearchParams.Radius = value;
OnSearchParamsChanged();
}
}
}
public int MinBedrooms
{
get { return SearchParams.MinBedrooms; }
set
{
if (SearchParams.MinBedrooms != value)
{
SearchParams.MinBedrooms = value;
OnSearchParamsChanged();
}
}
}
public int MaxBedrooms
{
get { return SearchParams.MaxBedrooms; }
set 
{ 
if (SearchParams.MaxBedrooms != value)
{
SearchParams.MaxBedrooms = value;
OnSearchParamsChanged();
}
}
}
public int MinPrice
{
get { return SearchParams.MinPrice; }
set 
{ 
if (SearchParams.MinPrice != value) 
{
SearchParams.MinPrice = value;
OnSearchParamsChanged();
}
}
}
public int MaxPrice
{
get { return SearchParams.MaxPrice; }
set
{
if (SearchParams.MaxPrice != value)
{
SearchParams.MaxPrice = value;
OnSearchParamsChanged();
}
}
}
public SortType SortType
{
get { return SearchParams.Sort; }
set
{
if (SearchParams.Sort != value)
{
SearchParams.Sort = value;
OnSearchParamsChanged();
}
}
}

public SearchParams SearchParams
{
get
{
SearchParams searchParams = (SearchParams)GetValue(SearchParamsProperty);
return searchParams;
}
set
{
SetValue(SearchParamsProperty, value);
}
}
// Using a DependencyProperty as the backing store for MySelectedItem.  This enables animation, styling, binding, etc...
public static readonly DependencyProperty SearchParamsProperty =
DependencyProperty.Register("SearchParams", typeof(SearchParams), typeof(SearchParamsControl), new PropertyMetadata(new SearchParams(), OnSearchParamsPropertyChanged));
public event PropertyChangedEventHandler PropertyChanged;
private static void OnSearchParamsPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
SearchParamsControl c = d as SearchParamsControl;
if (c != null)
{
c.OnSearchParamsChanged();
}
}
private void OnSearchParamsChanged()
{
OnPropertyChanged(nameof(SearchParams));
}
private void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
}

以及xml:

<UserControl x:Class="RightMoveApp.UserControls.SearchParamsControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
xmlns:local="clr-namespace:RightMoveApp.UserControls"
xmlns:System="clr-namespace:System;assembly=System.Runtime"
xmlns:StyleAlias="clr-namespace:RightMove;assembly=RightMove"
xmlns:viewModel="clr-namespace:RightMoveApp.ViewModel"
xmlns:dataTypes="clr-namespace:RightMove.DataTypes;assembly=RightMove" 
xmlns:valueconverters="clr-namespace:RightMoveApp.UserControls.ValueConverters"
mc:Ignorable="d" 
d:DesignHeight="450" d:DesignWidth="800"
x:Name="uc">
<UserControl.DataContext>
<viewModel:SearchParamsControlViewModel/>
</UserControl.DataContext>
<UserControl.Resources>
<ObjectDataProvider x:Key="dataFromEnum" MethodName="GetValues" ObjectType="{x:Type System:Enum}">
<ObjectDataProvider.MethodParameters>
<x:Type TypeName="dataTypes:SortType"/>
</ObjectDataProvider.MethodParameters>
</ObjectDataProvider>
<valueconverters:PropertyTypeConverter x:Key="PropertyTypeConverter" x:Shared="False"/>
<Style TargetType="{x:Type ComboBox}" BasedOn="{StaticResource ComboStyle}">
<Setter Property="Margin" Value="0,0,0,1"/>
</Style> 
</UserControl.Resources>
<Grid x:Name="LayoutRoot">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Label Grid.Column="0" Grid.Row="0" Content="Search area"/>
<local:AutoCompleteComboBox Grid.Row="0" Grid.Column="1"
ItemsSource="{Binding ElementName=uc, Path=SearchString}" 
SelectedValue="{Binding Path=RegionLocation, Mode=TwoWay}"/>
<Label Grid.Column="0" Grid.Row="1" Content="Search radius"/>
<ComboBox Template="{DynamicResource ComboBoxTemplate1}" Grid.Column="1" Grid.Row="1" Name="comboSearchRadius" 
ItemsSource="{Binding ElementName=uc, Path=RadiusEntries}" 
SelectedValuePath="Key" 
SelectedValue="{Binding ElementName=uc, Path=Radius, Mode=TwoWay}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Value}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<Label Grid.Column="0" Grid.Row="2" Content="Price range (£)"/>
<Grid Grid.Column="1" Grid.Row="2">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<ComboBox Grid.Column="0" Grid.Row="0" Name="comboMinPrice" 
ItemsSource="{Binding ElementName=uc, Path=Prices}" 
SelectedItem="{Binding ElementName=uc, Path=MinPrice, Mode=TwoWay}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<Label Grid.Column="1" Grid.Row="0" Content="to"/>
<ComboBox Grid.Column="2" Grid.Row="0" Name="comboMaxPrice"
ItemsSource="{Binding ElementName=uc, Path=Prices}" 
SelectedItem="{Binding ElementName=uc, Path=MaxPrice}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
</Grid>
<Label Grid.Column="0" Grid.Row="3" Content="No. of bedrooms"/>
<Grid Grid.Column="1" Grid.Row="3">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<ComboBox Grid.Column="0" Grid.Row="0" Name="comboMinBedrooms" 
ItemsSource="{Binding ElementName=uc, Path=Bedrooms}"
SelectedItem="{Binding ElementName=uc, Path=MinBedrooms, Mode=TwoWay}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<ComboBox Grid.Column="3" Grid.Row="0" Name="comboMaxBedrooms" 
ItemsSource="{Binding ElementName=uc, Path=Bedrooms}" 
SelectedItem="{Binding ElementName=uc, Path=MaxBedrooms, Mode=TwoWay}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<Label Grid.Column="1" Grid.Row="0" Content="to"/>
</Grid>
<Label Grid.Column="0" Grid.Row="4" Content="Sort Type"/>
<ComboBox Grid.Column="1" Grid.Row="4" Name="comboSort" 
ItemsSource="{Binding Source={StaticResource dataFromEnum}}"
SelectedItem="{Binding ElementName=uc, Path=SortType, Mode=TwoWay}">
</ComboBox>
</Grid>

我想绑定到MainWindow中的SearchParams依赖项属性，该属性包含SearchParamsControl:

<GroupBox Grid.Column="0" Grid.Row="0" Header="Search Params" Panel.ZIndex="10">
<controls:SearchParamsControl x:Name="searchControl"
SearchParams="{Binding Path=SearchParams, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
IsEnabled="{Binding Path=IsSearching, Converter={StaticResource BooleanToReverseConverter}}">
</controls:SearchParamsControl>
</GroupBox>
<Button x:Name="btnSearch" Grid.Column="0" Grid.Row="1" 
Content="Search" 
IsDefault="True"
Command="{Binding SearchAsyncCommand}"/>

这种装订效果很好。但是，正如你所看到的，我的主窗口中有一个按钮，它连接到一个命令。我想知道SearchParams中的属性何时更改，这样我就可以调用类似SearchCommandAsync.RiseCanExecuteChanged((的东西，这样我就能更新搜索按钮的状态。我该如何处理？

请注意，我不想使用以下注释掉的代码(来自我的Command类(，我认为这确实有效，但我希望能够通知SearchParams的属性发生了更改，因此我们需要再次调用CanExecute：

//public event EventHandler CanExecuteChanged
//{
//  add
//  {
//      CommandManager.RequerySuggested += value;
//  }
//  remove
//  {
//      CommandManager.RequerySuggested -= value;
//  }
//}
public event EventHandler CanExecuteChanged;
public void RaiseCanExecuteChanged()
{
//CommandManager.InvalidateRequerySuggested();
if (CanExecuteChanged != null)
{
CanExecuteChanged(this, new EventArgs());
}
}

此外，我不想用PropertyChanged事件处理程序修改SearchParams(假设它是一个封闭的类库，我无法修改它(。

Answer 1

如果我正确理解您的设置，视图上SearchParamsControl的SearchParams属性应在控件属性更改时设置视图模型的数据绑定SearchParams源属性。

然后可以在SearchParams源属性的setter中引发命令的CanExecuteChanged方法。