WPF ''local' 是一個未聲明的前綴

Question

我在定義local別名時遇到問題； 為什么它無效？

我有所有這些找不到的類。

錯誤列表

Error   3   ''local' is an undeclared prefix. Line 1, position 2.' XML is not valid.    c:\..\SofiaCarRental.WPF\Views\AddEditWindow.xaml   1   2   SofiaCarRental.WPF
Error   5   The attachable property 'Resources' was not found in type 'Window'. c:\..\SofiaCarRental.WPF\Views\AddEditWindow.xaml   8   6   SofiaCarRental.WPF
Error   2   The name "NullableBooleanConverter" does not exist in the namespace "clr-namespace:SofiaCarRental.WPF.Views".   c:\..\SofiaCarRental.WPF\Views\MainWindow.xaml  10  9   SofiaCarRental.WPF
Error   1   The namespace prefix "local" is not defined.    c:\..\SofiaCarRental.WPF\Views\AddEditWindow.xaml   1   1   SofiaCarRental.WPF
Error   4   The type 'local:BaseDialogWindow' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built.  c:\..\SofiaCarRental.WPF\Views\AddEditWindow.xaml   1   2   SofiaCarRental.WPF
Error   8   The type 'local:EmptyStringConverter' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built.  c:\..\SofiaCarRental.WPF\Views\AddEditWindow.xaml   11  10  SofiaCarRental.WPF
Error   6   The type 'local:NullableBooleanConverter' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built.  c:\..\SofiaCarRental.WPF\Views\AddEditWindow.xaml   9   10  SofiaCarRental.WPF
Error   7   The type 'local:YearConverter' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built. c:\..\SofiaCarRental.WPF\Views\AddEditWindow.xaml   10  10  SofiaCarRental.WPF

主窗口（這里我指定了“本地”）

<Window x:Class="SofiaCarRental.WPF.Views.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
    xmlns:local ="clr-namespace:SofiaCarRental.WPF.Views" 
    Title="Sofia Car Rental" 
    Height="720" Width="1280"
    MinHeight="720" MinWidth="1280">
<Window.Resources>
    <local:NullableBooleanConverter x:Key="booleanConverter" />
    <Style x:Key="checkBoxColStyle" TargetType="telerik:GridViewCell">
        <Setter Property="HorizontalContentAlignment" Value="Center" />
    </Style>
</Window.Resources>
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Width="Auto">
   ...
</Grid></Window>

添加編輯窗口

<local:BaseDialogWindow x:Class="SofiaCarRental.WPF.Views.AddEditWindow"
    xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="AddEditWindow" 
    Height="417" Width="383"
    Title="{Binding Path=Title}">
<Window.Resources>
    <local:NullableBooleanConverter x:Key="booleanConverter" />
    <local:YearConverter x:Key="yearConverter" />
    <local:EmptyStringConverter x:Key="emptyStringConverter" />
</Window.Resources>
<Grid Margin="20,10,50,10">
   ...
</Grid></local:BaseDialogWindow>

BaseDialogWindow 類：

namespace SofiaCarRental.WPF.Views
{
public class BaseDialogWindow : Window
{
    public BaseDialogWindow()
    {
        this.Owner = App.Current.MainWindow;
        this.ShowInTaskbar = false;
        this.ResizeMode = System.Windows.ResizeMode.NoResize;
        this.WindowStartupLocation = System.Windows.WindowStartupLocation.CenterOwner;
    }
}}

可空布爾轉換器

namespace SofiaCarRental.WPF.Views{
public class NullableBooleanConverter : IValueConverter
{
    public object Convert(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        object result = this.NullableBooleanToFalse(value);
        return result;
    }
    public object ConvertBack(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        object result = this.NullableBooleanToFalse(value);
        return result;
    }
    private object NullableBooleanToFalse(object value)
    {
        if (value == null)
        {
            return false;
        }
        else
        {
            return value;
        }
    }
}}

Answer 1

錯誤 3 ''local' 是一個未聲明的前綴。 第 1 行，位置 2。 XML 無效。 c:..\\SofiaCarRental.WPF\\Views\\AddEditWindow.xaml 1 2 SofiaCarRental.WPF

在文件AddEditWindow.xaml ，未聲明local前綴。 XML 命名空間聲明在逐個文件的基礎上工作。 它們不會被繼承，並且只對當前文件有效。 如果您想在該文件中使用來自其他命名空間的組件，您也必須在那里添加聲明。 你可以看到它們就像在代碼中using s 一樣——每當你想使用一個類型時，你必須先告訴編譯器在哪里尋找它：

<local:BaseDialogWindow x:Class="SofiaCarRental.WPF.Views.AddEditWindow"
    …
    xmlns:local="clr-namespace:SofiaCarRental.WPF.Views"
    … >

---

錯誤 5 在類型“Window”中找不到可附加屬性“Resources”。 c:..\\SofiaCarRental.WPF\\Views\\AddEditWindow.xaml 8 6 SofiaCarRental.WPF

雖然local:BaseDialogWindow是Window的子類型，但這仍然是此文件的類型。 編譯器在查看這部分的 XAML 時會看到這一點：

<SomeType …>
    <OtherType.Property>…</OtherType.Property>
</SomeType>

這基本上等同於：

<SomeType … OtherType.Property="…" />

由於OtherType與SomeType ，因此這是 XAML 中的附加屬性。 但是Window沒有名為Resources的附加屬性。

您想要做的是設置窗口的Resources屬性。 你的窗口類型是SomeType ，所以你需要這樣寫：

<SomeType …>
    <SomeType.Property>…</SomeType.Property>
</SomeType>

因此，在您的情況下，您希望像這樣設置資源：

<local:BaseDialogWindow x:Class="SofiaCarRental.WPF.Views.AddEditWindow"
        … >
    <local:BaseDialogWindow.Resources>
        …
    </local:BaseDialogWindow.Resources>
    …
</local:BaseDialogWindow>

---

其余的錯誤都是因為您使用了local:前綴而沒有先聲明它並且編譯器沒有找到您的類型。