我开始使用MVVM（使用Caliburn.Micro）并遇到了一个我不确定我是否正确执行此操作的问题。我有一个模型MediaCacherConfig，它表示以json格式存储数据的文本文件。该模型包含2个字符串列表和一个字符串。
我正在努力的是如何正确设置viewmodel，特别是AddNewFolder()方法。我不确定我是否正在提出正确的事件以及viewmodel的表示是否正确。我可以看到如何绑定到一个简单的属性，但绑定到一个集合似乎更像是一个头部微调器，因为我每次添加一个项目（字符串）时都会创建一个全新的集合。
此外，当我加载一个全新的模型时，我必须对所有对我没有意义的属性运行NotifyPropertyChanged（）方法。
非常感谢任何指导。
public class MediaCacherConfig : IConfig
{
public string DatabaseFileName { get; set; }
public ICollection<string> FoldersToScan { get; set; }
public ICollection<string> ExtensionsToIgnore { get; set; }
}
我有一个viewmodel MediaCacherConfigViewModel：
public class MediaCacherConfigViewModel : PropertyChangedBase
{
private MediaCacherConfig Model { get; set; }
public string DatabaseFileName
{
get { return Model.DatabaseFileName; }
set
{
Model.DatabaseFileName = value;
NotifyOfPropertyChange(() => DatabaseFileName);
}
}
public BindableCollection<string> FoldersToScan
{
get
{
return new BindableCollection<string>(Model.FoldersToScan);
}
set
{
Model.FoldersToScan = value;
NotifyOfPropertyChange(() => FoldersToScan);
}
}
public BindableCollection<string> ExtensionsToIgnore
{
get
{
return new BindableCollection<string>(Model.ExtensionsToIgnore);
}
set
{
Model.ExtensionsToIgnore = value;
NotifyOfPropertyChange(() => ExtensionsToIgnore);
}
}
/* Constructor */
public MediaCacherConfigViewModel()
{
LoadSampleConfig();
}
/* Methods */
public void LoadSampleConfig()
{
MediaCacherConfig c = new MediaCacherConfig();
string sampleDatabaseFileName = "testing.config";
List<string> sampleFoldersToScan = new List<string>();
sampleFoldersToScan.Add("A");
sampleFoldersToScan.Add("B");
sampleFoldersToScan.Add("C");
List<string> sampleExtensionsToIgnore = new List<string>();
sampleExtensionsToIgnore.Add("txt");
sampleExtensionsToIgnore.Add("mov");
sampleExtensionsToIgnore.Add("db");
sampleExtensionsToIgnore.Add("dat");
c.DatabaseFileName = sampleDatabaseFileName;
c.FoldersToScan = sampleFoldersToScan;
c.ExtensionsToIgnore = sampleExtensionsToIgnore;
Model = c;
NotifyOfPropertyChange(() => DatabaseFileName);
NotifyOfPropertyChange(() => FoldersToScan);
NotifyOfPropertyChange(() => ExtensionsToIgnore);
}
public void AddNewFolder()
{
Model.FoldersToScan.Add("new one added");
NotifyOfPropertyChange(() => FoldersToScan);
}
public void SaveConfig()
{
ConfigTools.Configure(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData), "Cacher", "Config"));
ConfigTools.SaveConfig(Model,"sampleconfig.txt");
}
public void LoadConfig()
{
ConfigTools.Configure(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData), "Cacher", "Config"));
MediaCacherConfig m = ConfigTools.LoadConfig<MediaCacherConfig>("sampleconfig.txt") as MediaCacherConfig;
Model = m;
NotifyOfPropertyChange(() => DatabaseFileName);
NotifyOfPropertyChange(() => FoldersToScan);
NotifyOfPropertyChange(() => ExtensionsToIgnore);
}
}
以下是我的观点：
<UserControl x:Class="MediaCacher.Views.MediaCacherConfigView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="413" Width="300">
<Grid MinWidth="300" MinHeight="300" Background="LightBlue" Margin="0,0,0,0">
<Grid.RowDefinitions>
<RowDefinition Height="409*"/>
<RowDefinition Height="4*"/>
</Grid.RowDefinitions>
<TextBox x:Name="DatabaseFileName" TextWrapping="Wrap" Margin="10,64,10,0" HorizontalAlignment="Center" Width="280" Height="42" VerticalAlignment="Top"/>
<ListBox x:Name="FoldersToScan" HorizontalAlignment="Left" Height="145" Margin="10,111,0,0" VerticalAlignment="Top" Width="280"/>
<ListBox x:Name="ExtensionsToIgnore" HorizontalAlignment="Left" Height="145" Margin="10,261,0,0" VerticalAlignment="Top" Width="280"/>
<Button x:Name="AddNewFolder" Content="Add" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Width="87" Height="49"/>
<Button x:Name="LoadConfig" Content="Load" HorizontalAlignment="Left" Margin="102,10,0,0" VerticalAlignment="Top" Width="96" Height="49"/>
<Button x:Name="SaveConfig" Content="Save" HorizontalAlignment="Left" Margin="203,10,0,0" VerticalAlignment="Top" Width="87" Height="49"/>
</Grid>
答案 0 :(得分：2)
首先，您每次都会返回一个全新的系列，所以很明显没有任何东西可以保留。
public BindableCollection<string> FoldersToScan
{
get
{
return new BindableCollection<string>(Model.FoldersToScan);
}
set
{
Model.FoldersToScan = value;
NotifyOfPropertyChange(() => FoldersToScan);
}
}
其次，您的AddFolder方法应该属于您的ViewModel。当您将字符串添加到现有集合时，它是BindingCollection的事实应该自动向View发起一个事件，即添加了一个新项目。
我就是这样做的。这显然是用于演示目的的示例，请添加您需要的所有其他内容。你想要传递EventArgs，并注意我没有实现INotifyPorpertyChanged，因为我没有时间全力以赴。我也在使用ObservableCollection，但您可以使用BindableCollection。
此示例的目的是向您展示如何管理ViewModel - ＆gt;模型沟通。从技术上讲，你的观点 - ＆gt; ViewModel应该通过CommandPattern进行交谈。
public class YourViewModel
{
private readonly YourModel model;
private ObservableCollection<string> foldersToScan = new ObservableCollection<string>();
public ObservableCollection<string> FoldersToScan
{
get { return this.foldersToScan; }
}
public YourViewModel(YourModel model)
{
this.model = model;
this.model.OnItemAdded += item => this.foldersToScan.Add(item);
}
public void AddFolder(string addFolder) //gets called from view
{
this.model.AddFolder(addFolder); //could be ICommand using Command Pattern
}
}
public class YourModel
{
private readonly List<string> foldersToScan;
public IEnumerable<string> FoldersToScan
{
get { return this.foldersToScan; }
}
public event Action<string> OnItemAdded;
public YourModel()
{
this.foldersToScan = new List<string>();
}
public void AddFolder(string folder)
{
this.foldersToScan.Add(folder);
this.RaiseItemAdded(folder);
}
void RaiseItemAdded(string folder)
{
Action<string> handler = OnItemAdded;
if (handler != null) handler(folder);
}
}