绑定对象的属性更改时，WPF Caliburn Micro CanExecute

Question

我遇到问题，当我更改绑定属性时，我的CanSave方法没有被调用。

查看

视图包含一些Labels和TextBoxes ......没什么特别的......

TextBoxes绑定到对象的属性。

<Label Target="{Binding ElementName=txtTitle}" Grid.Column="0" Grid.Row="0" Content="Titel" Foreground="White" />
<TextBox Name="txtTitle" Grid.Column="1" Grid.Row="0" Text="{Binding NewBook.Title}" />

<Label Target="{Binding ElementName=txtAuthor}" Grid.Column="0" Grid.Row="1" Content="Autor" Foreground="White" />
<TextBox Name="txtAuthor" Grid.Column="1" Grid.Row="1" Text="{Binding NewBook.Author}"/>

<Label Target="{Binding ElementName=txtIsbn}" Grid.Column="0" Grid.Row="2" Content="ISBN" Foreground="White" />
<TextBox Name="txtIsbn" Grid.Column="1" Grid.Row="2" Text="{Binding NewBook.Isbn}" />

<Label Target="{Binding ElementName=txtPrice}" Grid.Column="0" Grid.Row="3" Content="Preis" Foreground="White" />
<TextBox Name="txtPrice" Grid.Column="1" Grid.Row="3" Text="{Binding NewBook.Price}"/>

<Button Grid.Column="1" Grid.Row="4" Content="Speichern" Name="SaveBook" />

视图模型

ViewModel定义属性NewBook以及方法CanSaveBook和SaveBook

public Book NewBook
{
    get { return this.newBook; }
    set
    {
        this.newBook = value;
        this.NotifyOfPropertyChange(() => this.NewBook);
        this.NotifyOfPropertyChange(() => this.CanSaveBook);
    }
}

public bool CanSaveBook
{
    get
    {
        return !string.IsNullOrEmpty(this.NewBook.Title) 
                && !string.IsNullOrEmpty(this.NewBook.Author)
                && !string.IsNullOrEmpty(this.NewBook.Isbn) 
                && this.NewBook.Price != 0;
    }
}

public void SaveBook()
{
    try
    {
        this.xmlOperator.AddBook(ConfigurationManager.AppSettings.Get("BookXmlPath"), this.NewBook);
    }
    catch (Exception ex)
    {
        throw ex;
    }

    this.NewBook = new Book();
}

我想要的是，Save-Button仅在CanSaveBook返回true时可用，但在用户输入信息后检查CanSaveBook - 方法文本框...我错过了什么？

Answer 1

您遇到的问题是更改图书的属性不会在视图模型上引发INotifyPropertyChange。最简单的方法是摆脱Book类并将Name，Price，ISBN属性直接放在视图模型中。然后在setter中引发INotifyPropertyChange（并确保绑定是双向的）。

然后，您可以在SaveBook方法中构建Book并使用它来调用您的服务。