关于 c#:MVVM WPF ViewModel DispatcherTimer 不更新视图？

MVVM WPF ViewModel DispatcherTimer not updating view?

我的 ViewModel 中有一个 DispatcherTimer，我可以看到每个间隔都在触发，但是视图没有更新？

提要数据来自 xml url，我试图每 x 秒刷新一次表单。也许或多或少的标签/不同的状态

这里是代码片段：

ViewModel.cs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

public class Nodes
{
public string name { get; set; }
public string id { get; set; }
public string status { get; set; }
public string last { get; set; }
public int level { get; set; }
public string parent { get; set; }
}

public ObservableCollection<CI> CIs
{
get;
set;
}

DispatcherTimer LogTimer;

public void LoadCIs()
{
ObservableCollection<CI> cis = new ObservableCollection<CI>();

LogTimer = new DispatcherTimer();
LogTimer.Interval = TimeSpan.FromMilliseconds(10000);

LogTimer.Tick += (s, e) =>
{
//pull node list
List<Nodes> SortedList = PopulateNodes();

foreach (Nodes Node in SortedList)
{
//create labels for all top level nodes
if (Node.level == 3)
{
cis.Add(new CI { NodeName = Node.name, NodeStatus = Node.status });
}
}

CIs = cis;

};

LogTimer.Start();

}

模型.cs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42

public class CI : INotifyPropertyChanged {
private string nodeName;
private string nodeStatus;

public string NodeName {
get {
return nodeName;
}

set {
if (nodeName != value) {
nodeName = value;
RaisePropertyChanged("NodeName");
}
}
}

public string NodeStatus
{
get
{
return nodeStatus;
}

set
{
if (nodeStatus != value)
{
nodeStatus = value;
RaisePropertyChanged("NodeStatus");
}
}
}

public event PropertyChangedEventHandler PropertyChanged;

private void RaisePropertyChanged(string property) {
if (PropertyChanged != null) {
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
}

view.xaml

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

在没有启用/注释掉计时器的情况下表单的外观：

enter

启用计时器代码后，网格不会添加任何内容：

enter

1	cis.Add(new CI { NodeName = Node.name, NodeStatus = Node.status });

这样做：

1	cis.Add(new CI { NodeName = Node.name, NodeStatus = Node.status });

如果你这样做你必须先初始化CIs：

1
2
3
4
5

public ObservableCollection<CI> CIs
{
get;
set;
} = new ObservableCollection<CI>(); // < initialize it

选项 2：

将 INotifyPropertyChanged 接口添加到 Nodes 类并通知如下：

this.PropertyChanged?.Invoke( this, new PropertyChangedEventArgs( nameof( this.CIs ) ) );

在CIs

的setter中