So i have a View that i have bound to a List of Timer objects called Timers (custom class i have made), and in the view i have added a start and remove button. when a user clicks start i want them to be able to call the relevant timer object method startTimer() associated with the button. How can i do this?
View code:
<ContentPage.Content>
<StackLayout Orientation="Vertical">
<ListView ItemsSource="{Binding Timers, Mode=TwoWay}" SeparatorVisibility="None">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout HorizontalOptions="StartAndExpand" Orientation="Horizontal">
<StackLayout Padding="10,0,0,0" VerticalOptions="StartAndExpand" Orientation="Vertical">
<Label Text="{Binding _name, Mode=TwoWay}" YAlign="Center"/>
<Label Text="{Binding _startTime, Mode=TwoWay}" YAlign="Center" FontSize="Small"/>
</StackLayout>
<Button Text="Start" //button to associate with method//></Button>
<Button Text="Remove"></Button>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button Text="Add New" Clicked="AddNewTimer"/>
</StackLayout>
</ContentPage.Content>
My Binded Class:
public class MainViewModel : INotifyPropertyChanged
{
public MainViewModel ()
{
Timers = DependencyService.Get<ISaveAndLoad> ().LoadTimers ();
if (Timers == null) {
Timers = new ObservableCollection<Timer> ();
}
}
//When property changes notifys everything using it.
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String propertyName = "")
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
private ObservableCollection<Timer> _timers;
public ObservableCollection<Timer> Timers {
get { return _timers; }
set {
_timers = value;
NotifyPropertyChanged ("Timers");
}
}
private string _title;
public string Title{
get{
return _title;
}
set{
_title = value;
NotifyPropertyChanged ();
}
}
}
And the timer class:
public class Timer
{
public int _startTime { get; set;}
public bool _hasStarted{ get; set; }
public string _name { get; set; }
public Timer (string name, int startTime, bool hasStarted = false)
{
_name = name;
_startTime = startTime;
_hasStarted = hasStarted;
}
public void startTimer(){
//do something here
}
}
Cheers.
On your View XAML code you should add this to your start button:
<Button Text="Start" Command={Binding btnStartCommand} />
Then on your "My Binded Class: " you should create de ICommand property and initialize it on the constructor and then create the Command, something like this:
public ICommand btnStartCommand {get; set;}
public MainViewModel()
{
btnStartCommand = new Command(StartCommand);
}
public void StartCommand()
{
//here you create your call to the startTimer() method
}
Hope this helps you,
Cheers.
Related
Im trying to update my xamarin bindings from a object in my viewmodel. What am I doing wrong.
When i see look at the page and look at "User", i see my user object is there.
Page:
<StackLayout BindableLayout.ItemsSource="{Binding User}"
Orientation="Horizontal">
<BindableLayout.ItemTemplate>
<DataTemplate x:DataType="model:User">
<StackLayout>
<Label Text="{Binding Name, Mode=OneWay}"/>
<Label Text="{Binding PhoneNumber, Mode=OneWay}"/>
<Label Text="{Binding Adress, Mode=OneWay}"/>
<Label Text="{Binding Email, Mode=OneWay}"/>
</StackLayout>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>
What you need to know about the Viewmodel with mvvhelpers
public User User { get; set; }
public MyProfileViewModel()
{
Title = "MyProfile";
RefreshCommand = new AsyncCommand(Refresh);
AddCommand = new AsyncCommand(Add);
// RemoveCommand = new AsyncCommand<User>(Remove);
User = new User();
}
public async refrsh(){
User = await MyProfileService.GetMyProfile(2);
nameDisplay = User.Name;
}
string nameDisplay;
public string NameDisplay
{
get => nameDisplay;
set => SetProperty(ref nameDisplay, value);
}
According to Jason's opinion, you don't need to use BindableLayout and a DataTemplate if you only have a single User object, you can bind User Object to StackLayout BindingContext directly.
<StackLayout BindingContext="{Binding User}">
<Label Text="{Binding Name, Mode=OneWay}" />
<Label Text="{Binding PhoneNumber, Mode=OneWay}" />
<Label Text="{Binding Adress, Mode=OneWay}" />
<Label Text="{Binding Email, Mode=OneWay}" />
</StackLayout>
If you have collection of IEnumerable User, you can use BindableLayout.ItemsSource and a DataTemplate
You need to implement INotifyPropertyChanged for User properties, it will notify the data changes.
public class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void RaisePropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
The complete code:
<StackLayout>
<StackLayout BindingContext="{Binding User}">
<Label Text="{Binding Name, Mode=OneWay}" />
<Label Text="{Binding PhoneNumber, Mode=OneWay}" />
<Label Text="{Binding Adress, Mode=OneWay}" />
<Label Text="{Binding Email, Mode=OneWay}" />
</StackLayout>
<Button
x:Name="btn1"
Command="{Binding changecommand}"
Text="change user data" />
</StackLayout>
public partial class Page27 : ContentPage
{
public Page27()
{
InitializeComponent();
this.BindingContext = new MyProfileViewModel();
}
}
public class MyProfileViewModel
{
public User User { get; set;}
public ICommand changecommand { get; }
public MyProfileViewModel()
{
User = new User();
User.Name = "cherry";
User.PhoneNumber = "123";
User.Adress = "location 1";
User.Email = "xxxxx.#outlook.com";
changecommand = new Command(() =>
{
User.Name = "barry";
});
}
}
public class User:ViewModelBase
{
private string _Name;
public string Name
{
get { return _Name; }
set
{
_Name = value;
RaisePropertyChanged("Name");
}
}
private string _PhoneNumber;
public string PhoneNumber
{
get { return _PhoneNumber; }
set
{
_PhoneNumber = value;
RaisePropertyChanged("PhoneNumber");
}
}
private string _Adress;
public string Adress
{
get { return _Adress; }
set
{
_Adress = value;
RaisePropertyChanged("Adress");
}
}
private string _Email;
public string Email
{
get { return _Email; }
set
{
_Email = value;
RaisePropertyChanged("Email");
}
}
}
I'm trying to group various sliders elements to work together. In example if I have two elements, both are set to 50 (values goes from 0 to 100), the sum of the values must be always 100, so if I set one of the sliders to value 70, the other one must decrease dynamically to 30 value.
<ListView x:Name="listView"
ItemSource="myList">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Slider x:Name="slider"
Maximum="100"
Minimum="0"
Value="{Binding MyValue}"
HorizontalOptions="FillAndExpand"
MinimumTrackColor="Black"
MaximumTrackColor="Black"
ThumbColor="{StaticResource myColor}"
ValueChanged="OnValueChanged"
PropertyChanging="ChangingSliderValue"/>
<Label Text="{Binding Source={x:Reference slider}, Path=Value, StringFormat='{0:0}'}"
FontSize="Medium"
FontAttributes="Bold"
HorizontalOptions="End"
WidhtRequest="40"/>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
The C# class of my objects is
public class MyClass : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private int _value;
private string _name;
private bool _someBool;
public int MyValue { get {return _value;} set {_value = value;} }
public string Name { get {return _name;} set {_name = value;} }
public bool SomeBool { get {return _someBool;} set {_someBool = value; OnPropertyChanged();} }
void OnPropertyChanged ([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
And part of the class of the Xaml page is:
namespace MyApp
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class SliderPage: ContentPage
{
private ObservableCollection<MyClass> list = new ObservableCollection<MyClass>();
...
public SliderPage ()
{
InitializeComponent();
InitList();
listView.ItemsSource = list;
...
}
private void InitList () ...
private void ChangingSliderValue (object sender, PropertyChangedEventArgs e)
{
//Code to stick together the slider...
}
}
Any suggestion of how to achieve my goal?
work but is not showing dynamically
You need to implement the interface INotifyPropertyChanged on property MyValue so that the element will update in runtime .
By the way , since you had used data binding in your project . It would be better to handle logic in ViewModel. So you could modify the code like following
in Xmal
<ListView
ItemsSource="{Binding MySource}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout Orientation="Horizontal" HeightRequest="300" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
<Slider x:Name="slider"
Maximum="100"
Minimum="0"
Value="{Binding MyValue,Mode=TwoWay}"
HorizontalOptions="FillAndExpand"
MinimumTrackColor="Black"
MaximumTrackColor="Black"/>
<Label Text="{Binding Source={x:Reference slider}, Path=Value, StringFormat='{0:0}'}"
FontSize="20"
FontAttributes="Bold"
WidthRequest="40"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
in Code behind
Model
public class MyClass : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public int Id { get; set; } // add this property to index the slider
private int _value;
private string _name;
private bool _someBool;
public int MyValue {
get
{
return _value;
}
set
{
if(_value!=value)
{
_value = value;
OnPropertyChanged("MyValue");
}
}
}
public string Name { get { return _name; } set { _name = value; } }
public bool SomeBool { get { return _someBool; } set { _someBool = value; OnPropertyChanged("SomeBool"); } }
void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
ViewModel
public class MyViewModel
{
public ObservableCollection<MyClass> MySource { get; set; }
bool isFirstLoad = true;
public MyViewModel()
{
MySource = new ObservableCollection<MyClass>() {
new MyClass(){MyValue = 50,Id=0 },
new MyClass(){MyValue = 50,Id=1 },
};
foreach (MyClass model in MySource)
{
model.PropertyChanged += Model_PropertyChanged;
}
}
private void Model_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName== "MyValue")
{
//handle your logic here as you need
MyClass model = sender as MyClass;
foreach (MyClass item in MySource)
{
if (model.Id != item.Id)
{
item.MyValue = 100 - model.MyValue;
}
}
}
}
}
ContentPage
public xxxPage()
{
InitializeComponent();
BindingContext = new MyViewModel();
}
I'm developing an app with xamarin forms and the MVVM pattern. I have a page with a listview that has three buttons but all the time with only 2 visibles and change the visibility of two of them when I press a button. The problem is that for the first ten items it works like supposed to be, press the button and dissapear and appear the other, but after the 10th item when I press the button it dissapear but the other doesn't appear until I scrool the list view to a position where the item is out of the screen. When the item is out of the screen and come back to be on the screen, the button appear. The visibility of the buttons is controlled changing a boolean property that is binded to the IsVisible property of the button and one of them with a converter to negate the value of the property. This is a repository that you can clone and see the code and test, maybe is something with my Visual Studio.
Initially, I thought it could be for a race condition and made the method that change the variable synchronous but it doesn't work.
This is my list view
<ListView ItemsSource="{Binding Items}"
HasUnevenRows="True"
SeparatorVisibility="None"
IsRefreshing="False">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="{Binding Name}"/>
<StackLayout Orientation="Horizontal">
<Button Text="One"
HorizontalOptions="CenterAndExpand"
TextColor="Green"
BackgroundColor="White"
BorderColor="Green"
BorderWidth="1"
WidthRequest="150" />
<Button Text="Two"
HorizontalOptions="CenterAndExpand"
BackgroundColor="Green"
TextColor="White"
Command="{Binding TestCommand}"
WidthRequest="150"
IsVisible="{Binding TestVariable, Converter={StaticResource negate}}" />
<Button Text="Three"
HorizontalOptions="CenterAndExpand"
BackgroundColor="Red"
Command="{Binding TestCommand}"
TextColor="White"
WidthRequest="150"
IsVisible="{Binding TestVariable}" />
</StackLayout>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
The viewmodel
public class ListViewTestModel : BaseViewModel
{
private List<ListItemTestModel> items;
public List<ListItemTestModel> Items
{
get => items;
set
{
SetValue(ref items, value);
}
}
public ListViewTestModel()
{
List<ListItemTestModel> itemList = new List<ListItemTestModel>();
for (int i = 0; i < 40; i++)
{
itemList.Add(new ListItemTestModel { Name = "Test" });
}
Items = itemList;
}
}
And another view model that is binded to each item in the listView
public class ListItemTestModel : BaseViewModel
{
private bool testVariable;
public string Name { get; set; }
public bool TestVariable
{
get
{
return testVariable;
}
set
{
SetValue(ref testVariable, value);
}
}
public Command TestCommand { get; set; }
public ListItemTestModel()
{
TestCommand = new Command(() =>
{
TestMethod();
});
}
public void TestMethod()
{
TestVariable = !TestVariable;
}
}
the BaseViewModel
public class BaseViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
protected void SetValue<T>(ref T backingField, T value, [CallerMemberName] string propertyName = null)
{
if (EqualityComparer<T>.Default.Equals(backingField, value))
{
return;
}
backingField = value;
OnPropertyChanged(propertyName);
}
}
And the codebehind of the page
public partial class MainPage : ContentPage
{
public ListViewTestModel ViewModel { get; }
public MainPage()
{
ViewModel = new ListViewTestModel();
BindingContext = ViewModel;
InitializeComponent();
}
}
I suggest listview Caching Strategy may case this issue, the default value is RetainElement for ListView, so using CachingStrategy="RecycleElement" in ListView.
About listview Caching Strategy, you can take a look:
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/listview/performance#caching-strategy
You should definitely go to ObservableCollection type for your items thus you'll be able to observe and display any changes
private ObservableCollection<ListItemTestModel> items;
public ObservableCollection<ListItemTestModel> Items
{
get => items;
set => SetValue(ref items, value);
}
And you should set your BindingContext AFTER the InitializeComponent() method or property changed will be propagate before your view is initialized.
public MainPage()
{
InitializeComponent();
BindingContext = new ListViewTestModel();;
}
public ListViewTestModel()
{
List<ListItemTestModel> itemList = new List<ListItemTestModel>();
for (int i = 0; i < 40; i++)
{
itemList.Add(new ListItemTestModel { Name = "Test" });
}
Items = new ObservableCollection<ListItemTestModel>(itemList);
}
public class Zicker : INotifyPropertyChanged
{
public class MyClass
{
public string HeyName { get; set; }
public string HeySurname { get; set; }
public int HeyAge { get; set; }
}
public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged([CallerMemberName] string name = null)
{
if (PropertyChanged != null)
{
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(name));
}
}
private ObservableCollection<MyClass> _yourList = new ObservableCollection<MyClass>();
public ObservableCollection<MyClass> YourList
{
get
{
return _yourList;
}
set
{
_yourList = value;
RaisePropertyChanged("YourList");
RaisePropertyChanged("BindMeLabel");
}
}
public int BindMeLabel
{
get { return _yourList.Sum(a => a.HeyAge); }
}
public void WonCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
RaisePropertyChanged("BindMeLabel");
}
public List<string> heresamplenames = new List<string> { "Mohamed", "Zaran", "Ivan" };
public List<string> heresamplesurnames = new List<string> { "Pakou", "Simmone", "Zagoev" };
public List<int> heresampleages = new List<int> { 17,33,50 };
public Zicker()
{
ObservableCollection<MyClass> vs = new ObservableCollection<MyClass>();
for (int i = 0; i < 3; i++)
{ vs.Add(new MyClass { HeyName = heresamplenames[i], HeySurname = heresamplesurnames[i], HeyAge = heresampleages[i] }); }
YourList = vs; YourList.CollectionChanged += WonCollectionChanged;
}
}
<ContentPage.Content>
<StackLayout Orientation="Vertical" HorizontalOptions="Center" VerticalOptions="Center">
<ContentView HorizontalOptions="Fill" VerticalOptions="Fill">
<ListView HorizontalOptions="Center" VerticalOptions="Center" HasUnevenRows="True" ItemsSource="{Binding YourList}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"></ColumnDefinition>
<ColumnDefinition Width="1*"></ColumnDefinition>
<ColumnDefinition Width="1*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Label HorizontalTextAlignment="Center" VerticalTextAlignment="Center" Text="{Binding Path=HeyName}" Grid.Column="0" FontSize="12" TextColor="Black"></Label>
<Label HorizontalTextAlignment="Center" VerticalTextAlignment="Center" Text="{Binding Path=HeySurname}" FontSize="12" TextColor="Black" Grid.Column="1"/>
<Entry HorizontalTextAlignment="Center" VerticalOptions="Center" Text="{Binding Path=HeyAge}" FontSize="12" Keyboard="Numeric" TextColor="Black" Grid.Column="2"/>
</Grid>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentView>
<Label Text="{Binding BindMeLabel}" HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand" FontSize="40" TextColor="Black"></Label>
</StackLayout>
</ContentPage.Content>
public MainPage()
{
InitializeComponent();
BindingContext = new Zicker();
}
My Problem: In this List, there are three names, surnames, and ages. At the bottom, there is also a label which should be shown as the sum of Ages collection.
When the UI is starting, Label is working well. But, if I try to change any Ages entries, there is a big problem with the binding label.
I want to use MVVM structure but due to this problem, label binding is working just start up.
If you are updating the HeyName property, binding is not updating because the class MyClass does not implement INotifyPropertyChanged.
Try to replace the MyClass class with this code:
public class MyClass : INotifyPropertyChanged
{
private string name;
private string surname;
private int age;
public string HeyName
{
get => name;
set
{
name = value;
RaisePropertyChanged("HeyName");
}
}
public string HeySurname
{
get => surname;
set
{
surname = value;
RaisePropertyChanged("HeySurname");
}
}
public int HeyAge
{
get => age;
set
{
age = value;
RaisePropertyChanged("HeyAge");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged([CallerMemberName] string name = null)
{
if (PropertyChanged != null)
{
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(name));
}
}
}
EDIT:
Sorry, the CollectionChanged is not called when you update the HeyAge property, because it is called only if the collection is changed, but not when a property of an item in the collection changes.
Try to add the OnAgeChanged event into the class MyClass and call it when the HeyAge property change:
public class MyClass : INotifyPropertyChanged
{
public event EventHandler OnAgeChanged;
public int HeyAge
{
get => age;
set
{
age = value;
RaisePropertyChanged("HeyAge");
OnAgeChanged?.Invoke(this, EventArgs.Empty);
}
}
...
...
Then, when you add a new MyClass object into the collection, register the event in the ViewModel like this:
public Zicker()
{
ObservableCollection<MyClass> vs = new ObservableCollection<MyClass>();
for (int i = 0; i < 3; i++)
{
var test = new MyClass()
{
HeyName = heresamplenames[i],
HeySurname = heresamplesurnames[i],
HeyAge = heresampleages[i],
};
test.OnAgeChanged += Test_OnAgeChanged;
vs.Add(test);
}
YourList = vs;
YourList.CollectionChanged += WonCollectionChanged;
}
private void Test_OnAgeChanged(object sender, EventArgs e)
{
RaisePropertyChanged("BindMeLabel");
}
Note that the WonCollectionChanged it's not necessary any more.
Note also that the variable vs is not needed, you can work directly into the YourList object instead.
I have a UI which displays a ListView in a ListView:
<ListView
SelectedIndex="{x:Bind ParentViewModel.SelectedParentIndex, Mode=TwoWay}"
ItemsSource="{x:Bind ParentViewModel.ParentViewModels, Mode=OneWay}">
<ListView.ItemTemplate>
<DataTemplate x:DataType="viewModels:ParentViewModel">
<StackPanel>
<TextBlock Text="{Binding ParentName}" />
<ListView
SelectedIndex="{x:Bind SelectedChildIndex, Mode=TwoWay}"
ItemsSource="{Binding ChildViewModels, Mode=OneWay}">
<ListView.ItemTemplate>
<DataTemplate x:DataType="viewModels:ChildViewModel">
<TextBlock Text="{Binding ChildName}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
When I click on a parent element the SelectedParentIndex gets set and when I click on a child element the SelectedChildIndex gets set.
My problem is that when I click on a child element i don't know to wich parent element it belongs because the SelectedParentIndex is not set. How can I solve this?
And the flow how it should be:
Just add an event in. Here is a compiled working example.
<ListView
ItemsSource="{Binding ParentViewModels, Mode=OneWay}"
SelectedIndex="{Binding SelectedParentIndex, Mode=TwoWay}"
SelectedItem="{Binding SelectedParent,Mode=TwoWay}">
<ListView.ItemTemplate>
<DataTemplate >
<StackPanel>
<TextBlock Text="{Binding ParentName}" />
<ListView
ItemsSource="{Binding ChildViewModels, Mode=OneWay}"
SelectedIndex="{Binding SelectedChildIndex, Mode=TwoWay}"
SelectedItem="{Binding SelectedChild,Mode=TwoWay}">
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding ChildName}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Here are the cs files. Please pay close attention to the structure.
The MasterViewModel is your DataContext for your View. It handles the SelectedParent, the SelectedParentIndex and your parents collection.
public class MasterViewModel : ViewModelBase
{
private ParentViewModel _SelectedParent;
public ParentViewModel SelectedParent
{
get { return _SelectedParent; }
set
{
_SelectedParent = value;
OnPropertyChanged("SelectedParent");
}
}
private int _SelectedParentIndex;
public int SelectedParentIndex
{
get { return _SelectedParentIndex; }
set
{
_SelectedParentIndex = value;
OnPropertyChanged("SelectedParentIndex");
}
}
public ObservableCollection<ParentViewModel> ParentViewModels
{
get; private set;
}
public MasterViewModel()
{
ParentViewModels = new ObservableCollection<ParentViewModel>();
LoadData();
}
private void LoadData()
{
for(int x = 0; x < 10; x++)
{
ParentViewModel parent = new ParentViewModel();
parent.ChildChangedEvent += Parent_ChildChangedEvent;
for(int y = 0; y < 20; y++)
{
ChildViewModel child = new ChildViewModel()
{ ChildName = "Child " + y };
parent.ChildViewModels.Add(child);
}
ParentViewModels.Add(parent);
}
}
private void Parent_ChildChangedEvent(object sender, EventArgs e)
{
SelectedParent = (ParentViewModel)sender;
}
}
Your ParentViewModel contains your SelectedChildIndex, your SelectedChild and your ChildViewModels collection. It also has a name property
Notice that I added an EventHandler to your ParentViewModel. When the SelectedChild is updated, it fires the event off. Then, we handle this event in the MasterViewModel where we can force the SelectedParent to update.
public class ParentViewModel : ViewModelBase
{
public String ParentName { get; set; }
private int _SelectedChildIndex;
public int SelectedChildIndex
{
get { return _SelectedChildIndex; }
set
{
_SelectedChildIndex = value;
OnPropertyChanged("SelectedChildIndex");
}
}
private ChildViewModel _SelectedChild;
public ChildViewModel SelectedChild
{
get { return _SelectedChild; }
set
{
_SelectedChild = value;
OnPropertyChanged("SelectedChild");
if (ChildChangedEvent != null)
{
ChildChangedEvent(this, new EventArgs());
}
}
}
public ObservableCollection<ChildViewModel> ChildViewModels
{
get; private set;
}
public event EventHandler ChildChangedEvent;
public ParentViewModel()
{
ChildViewModels = new ObservableCollection<ChildViewModel>();
}
}
Your ChildViewModel just has a name property.
public class ChildViewModel : ViewModelBase
{
private string _childName;
public string ChildName
{
get { return _childName; }
set
{
_childName = value;
OnPropertyChanged("ChildName");
}
}
}
The ViewModelBase just updates the UI
public class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propName));
}
}
}