CODEWITHSUNDEEP
c#xamarinxamarin.iosxamarin.forms
Atul
Atul

Reputation: 440

Property value doesn't update value to Label in UI in Xamarin Forms

I have a button and want to update UI Label value on button click from ViewModel. I implemented INotifyPropertyChanged but it is not working. Property value doesn't update value to Label in UI in Xamarin Forms

MyViewModel

public class MyViewModel : INotifyPropertyChanged
    { 
        public ICommand selectDurationCommand;
        public ICommand SelectDurationCommand
        {
            get { return selectDurationCommand; }
            set
            {
                selectDurationCommand = value;
                OnPropertyChanged();
            }
        }
        public string _fare{ get; set; } 
        public string Fare
        {
            get { return _fare; }
            set
            {
                _fare = value;
                OnPropertyChanged();
            }
        }      
        public event PropertyChangedEventHandler PropertyChanged;
        public MyViewModel()
        {
           selectDurationCommand = new Command((object s) => get_fare(s));
            _fare = "$00.00";
        }
       public void get_fare(object btn)
        {
            var b = (Button)btn;
            _fare="$03.00";
        }
 protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
                handler(this, new PropertyChangedEventArgs(propertyName));
        }
}

FareDetails.xaml

<cl:BasePage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="familyinfo.FareDetails" xmlns:cl="clr-namespace:familyinfo;assembly=familyinfo" x:Name="PDuration">
<Label FontSize="22" TextColor="Black" VerticalOptions="FillAndExpand" Font="Roboto-Medium" Text="{Binding Fare}" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" />
<Button Command="{Binding Source={x:Reference PDuration}, Path=BindingContext.SelectDurationCommand}" CommandParameter="{x:Reference min15Button}" x:Name="min15Button" HeightRequest="30" HorizontalOptions="FillAndExpand" BorderRadius="8" Text="15 MIN" TextColor="#ffffff" BackgroundColor="#f2415c" />
</cl:BasePage>

FareDetails.xaml.cs

public partial class FareDetails : BasePage
    {
        MyViewModel _MyViewModel { get; set; }
        public FareDetails()
        {
            InitializeComponent();
            _MyViewModel = (MyViewModel)this.BindingContext;
        }
}

Upvotes: 2

Views: 2591

Answers (2)

VenkyDhana
VenkyDhana

Reputation: 905

Can you ensure that the value of the (MyViewModel)this.BindingContext is not null?

Replace the below code and check whether label value is showing or not

MyViewModel _MyViewModel { get; set; }
 public FareDetails()
 {
    _MyViewModel = new MyViewModel();
    BindingContext = _MyViewModel;
    InitializeComponent();

  }

Also set the public property (Fare = "$0.00") instead of private property (_fare = "$0.00")

Upvotes: 0

pinedax
pinedax

Reputation: 9346

For the PropertyChanged notification to be raised you need to set the value to the Property not to the private field.

Change your Command method to this:

public void get_fare(object btn)
{
     var b = (Button)btn;
     Fare="$03.00";
}

Note: your _fare can safely be a private field. 

private string _fare;
public string Fare
{
    get { return _fare; }
    set
    {
        _fare = value;
        OnPropertyChanged();
    }
}

Upvotes: 3

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