嗨,美好的一天,我是WPF和MVVM设计模式的新手,我从PRISM的BRIAN LAGUNAS先生的博客和视频中学到了很多东西......但只是想问一个菜鸟问题。 .whats错误的我的代码它为我工作...任何帮助非常感谢谢谢。 这是我的代码:
我的观看模式
public class Person : BindableBase
{
private myPErson _MyPerson;
public myPErson MyPerson
{
get { return _MyPerson; }
set
{
SetProperty(ref _MyPerson, value);
}
}
public Person()
{
_MyPerson = new myPErson();
updateCommand = new DelegateCommand(Execute, CanExecute).ObservesProperty(() => MyPerson.FirstName).ObservesProperty(() => MyPerson.Lastname);
// updateCommand = new DelegateCommand(Execute).ObservesCanExecute((p) => CanExecute); /// JUST WANNA TRY THIS BUT DUNNO HOW
}
private bool CanExecute()
{
return !String.IsNullOrWhiteSpace(MyPerson.FirstName) && !String.IsNullOrWhiteSpace(MyPerson.Lastname);
}
private void Execute()
{
MessageBox.Show("HOLA");
}
public DelegateCommand updateCommand { get; set; }
}
基于myModel
声明为另一个类文件
public class myPErson : BindableBase
{
private string _firstName;
public string FirstName
{
get { return _firstName; }
set
{
SetProperty(ref _firstName, value);
}
}
private string _lastname;
public string Lastname
{
get { return _lastname; }
set
{
SetProperty(ref _lastname, value);
}
}
}
查看 Xaml代码
<Window x:Class="Prism6Test.Views.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:myVM="clr-namespace:Prism6Test.ViewModel"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<myVM:Person x:Key="mainVM"/>
</Window.Resources>
<Grid DataContext="{StaticResource mainVM}">
<TextBox HorizontalAlignment="Left" Height="23" Margin="217,103,0,0" TextWrapping="Wrap" Text="{Binding MyPerson.FirstName,UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
<TextBox HorizontalAlignment="Left" Height="23" Margin="217,131,0,0" TextWrapping="Wrap" Text="{Binding MyPerson.Lastname,UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="120"/>
<Button Content="Button" Command="{Binding updateCommand}" HorizontalAlignment="Left" Margin="242,159,0,0" VerticalAlignment="Top" Width="75"/>
</Grid>
</Window>
我已经读过这个但它对我不起作用..并且无法理解我怎样才能正确编码...请帮我理解这件事..希望对于任何回复很快..thx
ObservesProperty method isn't observing model's properties at Prism 6
答案 0 :(得分:4)
1)你不能像你想的那样使用复杂的数据模型,所以试试吧
private myPErson _MyPerson;
public myPErson MyPerson
{
get { return _MyPerson; }
set
{
if (_MyPerson != null)
_MyPerson.PropertyChanged -= MyPersonOnPropertyChanged;
SetProperty(ref _MyPerson, value);
if (_MyPerson != null)
_MyPerson.PropertyChanged += MyPersonOnPropertyChanged;
}
}
private void MyPersonOnPropertyChanged(object sender, PropertyChangedEventArgs propertyChangedEventArgs)
{
updateCommand.RaiseCanExecuteChanged();
}
2)更改构造函数
public Person()
{
MyPerson = new myPErson();
updateCommand = new DelegateCommand(Execute, CanExecute);
}
答案 1 :(得分:3)
首先我要谈谈你的命名。为您的课程命名清楚。调用您的 ViewModel ,例如当您的应用程序不是那么大而不是PersonViewModel
时,ViewModel
或仅Person
,因为Person
显然是模型。此外,myPErson
是一个非常糟糕的名称,因为它与您的其他Person
类非常相似,您应该PascalCase您的类名。
现在代码。我对Prism
一无所知,所以我的代码只有在没有Prism Libraries支持的情况下依赖于MVVM
模式。
首先,我要更改模型 Person
。我的代码中的类看起来非常简单(只使用自动属性):
public class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
public Person()
{
this.LastName = string.Empty;
this.FirstName = string.Empty;
}
}
PersonViewModel
有点复杂,因为它实现了INotifyPropertyChanged
接口。我也使用了您可以在接受的答案下的链接中找到的非常常见的RelayCommand。
public class PersonViewModel : INotifyPropertyChanged
{
private Person person;
private ICommand updateCommand;
public PersonViewModel()
{
this.Person = new Person();
}
public event PropertyChangedEventHandler PropertyChanged;
public Person Person
{
get
{
return this.person;
}
set
{
this.person = value;
// if you use VS 2015 or / and C# 6 you also could use
// this.OnPropertyChanged(nameof(Person));
this.OnPropertyChanged("Person");
}
}
public ICommand UpdateCommand
{
get
{
if (this.updateCommand == null)
{
this.updateCommand = new RelayCommand<Person>(this.OpenMessageBox, this.OpenMessageBoxCanExe);
}
return this.updateCommand;
}
}
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
private void OpenMessageBox(Person person)
{
MessageBox.Show("Hola");
}
private bool OpenMessageBoxCanExe(Person person)
{
if (person == null)
{
return false;
}
if (string.IsNullOrWhiteSpace(person.FirstName) || string.IsNullOrWhiteSpace(person.LastName))
{
return false;
}
return true;
}
}
我清理了你的视图,因为它现在要短得多。但总的来说,一切都保持不变。我刚刚重命名了属性和东西:
<Window ...>
<Window.Resources>
<wpfTesst:PersonViewModel x:Key="ViewModel" />
</Window.Resources>
<Grid DataContext="{StaticResource ViewModel}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TextBox Grid.Row="0" TextWrapping="Wrap" Text="{Binding Person.FirstName, UpdateSourceTrigger=PropertyChanged}" />
<TextBox Grid.Row="1" TextWrapping="Wrap" Text="{Binding Person.LastName, UpdateSourceTrigger=PropertyChanged}" />
<Button Grid.Row="2" Content="Button" Command="{Binding UpdateCommand}" CommandParameter="{Binding Person}"/>
</Grid>
</Window>
总而言之,我建议你使用没有Prism Library的常见MVVM模式。当你理解MVVM的优点时,你仍然可以选择Prism。 希望它有所帮助。
答案 2 :(得分:0)
查看Xaml代码
<Window x:Class="Prism6Test.Views.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:myVM="clr-namespace:Prism6Test.ViewModel"
Title="MainWindow" Height="350" Width="525">
您缺少ViewModelLocator
xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
prism:ViewModelLocator.AutowireViewModel="True"