Reputation: 5
I have the following situation: I have an app, where I want to create notes using a special page for it. I have VM with ObservableCollection NoteItems with all the notes. When I want to create a new note, I add a new note to this ObservableCollection and pass this new note using BindingContext
var editingPage = new EditingPage();
editingPage.BindingContext = NoteItems[NoteItems.Count - 1].Text;
Application.Current.MainPage.Navigation.PushAsync(editingPage);
In the editing page I have an Entry field
<Entry
x:Name="EdtingPageEntryField"
Text="{Binding Text}"
Placeholder="Enter a note"
/>
, which is Binding his text with the Text parameter of a NoteItem. The problem is that if I change the text in entry field, it does not automatically apply to a Text parameter of a NoteItem. That is why I want to pass this text when I close this EditingPage(go back to the MainPage). So the question is, how can I pass this Text parameter to a NoteItem element from NoteItems ObservableCollection, which is located in VM.
UPD. The value of NoteItem, which is located in NoteItems does not change
UPD2. I was wrong about the value of NoteItem, it has been changed, but the new value does not display on MainPage, that is why I used INotifyPropertyChanged, but it did not work.
Here is Note Item class
public class NoteItem
{
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private string text;
public string Text
{
get { return text; }
set
{
if(text != value)
{
text = value;
NotifyPropertyChanged();
}
}
}
And MainPage.xaml:
<ContentPage.BindingContext>
<local:NoteItemViewModel/>
</ContentPage.BindingContext>
<FlexLayout>
<ListView ItemsSource="{Binding NoteItems}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Label Text="{Binding Text}"/>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</FlexLayout>
'''
Upvotes: 0
Views: 676
Reputation: 89214
in order to dynamically update the UI, your model must implement INotifyPropertyChanged
public class NoteItem : INotifyPropertyChanged
{
...
}
simply adding a PropertyChanged
method is not the same as implementing INotifyPropertyChanged
. You must add the interface to the class definition so that the binding mechanism knows that your class has implemented it
Upvotes: 1