(资料图片)

CommunityToolkit.Mvvm8.1有一个重大更新的功能:源生成器功能,它极大简化我们的mvvm代码

但是本篇先总结一下原写法,下篇再总结源生成器功能

必须继承:ObservableObject

几个关键点:

SetProperty是给属性赋值,并且通知更改通知ButtonClickCommand.NotifyCanExecuteChanged(); //通知命令 已经改变RelayCommand ButtonClickCommand //定义命令

namespace WpfDemoNet6.Demo{    public class DataViewModel1 : ObservableObject    {        private string title = "hello";        public string Title        {            get            {                return title;            }            set            {                //title = value;                //PropertyChanged?.Invoke( this , new PropertyChangedEventArgs( "Name" ) );                //SetProperty 相当与设置值,并且PropertyChanged通知调用                SetProperty( ref title , value );            }        }        private bool isEnabled = false;        /// 
        /// 是否可以使用        /// 
        public bool IsEnabled        {            get => isEnabled;            set            {                SetProperty( ref isEnabled , value );                //通知命令 已经改变                ButtonClickCommand.NotifyCanExecuteChanged();            }        }        /// 
        /// 命令        /// 
        public RelayCommand ButtonClickCommand        {            get;        }        public DataViewModel1 ()        {            //RelayCommand的第一个参数是命令调用语句            //              第2个参数(可选)是否允许使用            ButtonClickCommand = new RelayCommand( () =>            {                //点击按钮,修改标题                Title = "hello(改)";            } , () =>            {                return IsEnabled;            } );            ButtonClickCommandPar = new RelayCommand( ( double val ) =>            {                Title = $"hello(改):{val}";            } );        }        public RelayCommand ButtonClickCommandPar        {            get;        }    }}

异步命令会自动控制控件的可见性,并且提供一个IsRunning属性可以判断异步是否完成

public DataViewModel1 (){    AsyncButtonClickCommand = new AsyncRelayCommand( RunTxtAsync );    AsyncButtonParClickCommand = new AsyncRelayCommand( RunTxtParAsync );}/*特别说明：异步命令会自动控制控件的可见性,并且提供一个IsRunning属性可以判断异步是否完成*//// 
/// 命令/// 
public IAsyncRelayCommand AsyncButtonClickCommand{    get;}private async Task RunTxtAsync (){    await Task.Delay( 4800 );    Title = "hello(Task改)";}/// 
/// 命令(带参数的)/// 
public IAsyncRelayCommand AsyncButtonParClickCommand{    get;}private async Task RunTxtParAsync ( double val ){    await Task.Delay( 4800 );    Title = $"hello(Task改):{val}";}