当设置 PropertyMetadata 中的默认值是字符串数组时无法获取项目的值

Question

我的自定义控件中有一个 DependencyProperty。我已将 DayOfWeeksProperty 的默认值设置为字符串值数组，然后将 PropertyChangedCallback 设置为一种方法，其中 TextBlock 是默认数组中每个元素的设置值。

public string[] DayOfWeeks
        {
            get { return (string[])GetValue(DayOfWeeksProperty); }
            set { SetValue(DayOfWeeksProperty, value); }
        }

        // Using a DependencyProperty as the backing store for DayOfWeeks.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty DayOfWeeksProperty =
            DependencyProperty.Register(
                "DayOfWeeks",
                typeof(string[]),
                typeof(ScheduleControl),
                new PropertyMetadata(
                    new string[7] { "Volvo", "BMW", "Ford", "Mazda", "BMW", "Ford", "Mazda" },
                    OnDayOfWeeksChanged)
                );

        private static void OnDayOfWeeksChanged(
            DependencyObject dependencyObject,
            DependencyPropertyChangedEventArgs e)
        {
            ScheduleControl scheduleControl = dependencyObject as ScheduleControl;
            scheduleControl.OnDayOfWeeksChanged(e);
        }

        private void OnDayOfWeeksChanged(DependencyPropertyChangedEventArgs e)
        {
            string[] dayOfWeeks = (string[]) e.NewValue;
            TextBlock_Monday.Text = dayOfWeeks[0];
            TextBlock_Tuesday.Text = dayOfWeeks[1];
            TextBlock_Wednesday.Text = dayOfWeeks[2];
            TextBlock_ThursDay.Text = dayOfWeeks[3];
            TextBlock_Friday.Text = dayOfWeeks[4];
            TextBlock_Saturday.Text = dayOfWeeks[5];
            TextBlock_Sunday.Text = dayOfWeeks[6];
        }

XAML

<UserControl
    x:Class="cs4rsa_core.Controls.ScheduleControl"
    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"
    d:DesignHeight="450"
    d:DesignWidth="800"
    mc:Ignorable="d">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <TextBlock
            x:Name="TextBlock_TimeLineHeading"
            Grid.Row="0"
            Grid.Column="0" />
        <TextBlock
            x:Name="TextBlock_Monday"
            Grid.Row="0"
            Grid.Column="1" />
        <TextBlock
            x:Name="TextBlock_Tuesday"
            Grid.Row="0"
            Grid.Column="2" />
        <TextBlock
            x:Name="TextBlock_Wednesday"
            Grid.Row="0"
            Grid.Column="3" />
        <TextBlock
            x:Name="TextBlock_ThursDay"
            Grid.Row="0"
            Grid.Column="4" />
        <TextBlock
            x:Name="TextBlock_Friday"
            Grid.Row="0"
            Grid.Column="5" />
        <TextBlock
            x:Name="TextBlock_Saturday"
            Grid.Row="0"
            Grid.Column="6" />
        <TextBlock
            x:Name="TextBlock_Sunday"
            Grid.Row="0"
            Grid.Column="7" />
        <ListView Grid.Row="1" Grid.Column="0" ItemsSource="{Binding}" SelectedItem="" />
        <ListView Grid.Row="1" Grid.Column="1" ItemsSource="{Binding}" SelectedItem="" />
        <ListView Grid.Row="1" Grid.Column="2" ItemsSource="{Binding}" SelectedItem="" />
        <ListView Grid.Row="1" Grid.Column="3" ItemsSource="{Binding}" SelectedItem="" />
        <ListView Grid.Row="1" Grid.Column="4" ItemsSource="{Binding}" SelectedItem="" />
        <ListView Grid.Row="1" Grid.Column="5" ItemsSource="{Binding}" SelectedItem="" />
        <ListView Grid.Row="1" Grid.Column="6" ItemsSource="{Binding}" SelectedItem="" />
        <ListView Grid.Row="1" Grid.Column="7" ItemsSource="{Binding}" SelectedItem="" />
    </Grid>
</UserControl>

我希望默认数组中的值分别显示在每个TextBlock上，但是当我运行程序时，没有任何反应

Answer 1

我已经在Constructor中为它设置了默认值，它起作用了。

public ScheduleControl()
{
    InitializeComponent();
    string[] defaultDayOfWeeks =
    {
        "Monday",
        "Tuesday",
        "Wednesday",
        "Thursday",
        "Friday",
        "Saturday",
        "Sunday",
    };
    SetValue(DayOfWeeksProperty, defaultDayOfWeeks);
}

参考：https://docs.microsoft.com/en-us/dotnet/desktop/wpf/properties/collection-type-dependency-properties?view=netdesktop-6.0

当设置 PropertyMetadata 中的默认值是字符串数组时无法获取项目的值

Cannot get value of item when set Default value in PropertyMetadata is Array of string

wpf

dependency-properties