在命令中设置属性时，绑定不会更新

本文介绍了在命令中设置属性时，绑定不会更新的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个令人惊讶的困难，试图使一个简单的事情工作，即设置一个属性在一个方法调用一个命令绑定到一个按钮。

I am having a surprising difficulty trying to make a simple thing work, that is, setting a property in a method called by a Command bound to a Button.

当我在ViewModel构造函数中设置属性时，正确的值在View中正确显示，但是当我使用命令的方法设置此属性时，尽管我创建的任何断点（甚至在 RaisePropertyChanged 在我的 ViewModelBase 中）。我正在使用在线教程（来自乔希·史密斯，如果我没有误会）容易找到的香草 RelayCommand 。

When I set the property in the ViewModel constructor, the correct value is properly displayed in View, but when I set this property with the command's method, the View doesn't update, although any breakpoint I create is reached (even inside RaisePropertyChanged in my ViewModelBase). I am using vanilla RelayCommand found easily in online tutorials (from Josh Smith if I am not mistaken).

我的项目可以下载 here （Dropbox）;

My project can be downloaded here (Dropbox);

一些重要的代码块如下：

Some important code blocks are below:

ViewModel：

ViewModel:

public class IdiomaViewModel : ViewModelBase { public String Idioma { get { return _idioma; } set { _idioma = value; RaisePropertyChanged(() => Idioma); } } String _idioma; public IdiomaViewModel() { Idioma = "nenhum"; } public void Portugues () { Idioma = "portu"; } private bool PodePortugues() { if (true) // <-- incluir teste aqui!!! return true; return false; } RelayCommand _comando_portugues; public ICommand ComandoPortugues { get { if (_comando_portugues == null) { _comando_portugues = new RelayCommand(param => Portugues(), param => PodePortugues()); } return _comando_portugues; } } public void Ingles () { Idioma = "ingle"; } private bool PodeIngles() { if (true) // <-- incluir teste aqui!!! return true; return false; } RelayCommand _comando_ingles; public ICommand ComandoIngles { get { if (_comando_ingles == null) { _comando_ingles = new RelayCommand(param => Ingles(), param => PodeIngles()); } return _comando_ingles; } } }

没有额外的代码：

<Window x:Class="TemQueFuncionar.MainWindow" xmlns="schemas.microsoft/winfx/2006/xaml/presentation" xmlns:x="schemas.microsoft/winfx/2006/xaml" xmlns:app="clr-namespace:TemQueFuncionar" Title="MainWindow" Height="350" Width="525"> <Window.DataContext> <app:IdiomaViewModel/> </Window.DataContext> <StackPanel> <Button Content="Ingles" Command="{Binding ComandoIngles, Mode=OneWay}"/> <Button Content="Portugues" Command="{Binding ComandoPortugues, Mode=OneWay}"/> <Label Content="{Binding Idioma}"/> </StackPanel> </Window>

推荐答案

Youdid填写接口实现，你没有提到到基本视图模型。 你错过了这个：INotifyPropertyChanged 链接到基类的接口，这使得View刷新内容。

Youdid fill the Interface implementation put you did not mention it to the base view model. You are missing this : INotifyPropertyChanged linking Interface to the base class, this makes the the View refreshes the content.