CODEWITHSUNDEEP
c#xamarinxamarin.forms
user1943020
user1943020

Reputation:

Value cannot be null message when implementing PropertyChangedEvent

I have this C# code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Threading;
namespace City
{
    public static class MS 
    {

        public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged;

        private static void NotifyStaticPropertyChanged(string propertyName)
        {
            if (StaticPropertyChanged != null)
                StaticPropertyChanged(null, new PropertyChangedEventArgs(propertyName));
        }

        private static int timerSeconds;
        public static int TimerSeconds
        {
            get { return timerSeconds; }
            set { timerSeconds = value; NotifyStaticPropertyChanged("TimerSeconds"); }
        }
    }
}

and this XAML

 <Frame xmlns="http://xamarin.com/schemas/2014/forms" 
  xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
  x:Class="City.Test">

 <Label x:Name="timer" Text="{Binding Source={x:Static local:MS.TimerSeconds}}" />
        </Grid>

When I compile it gives me a compile error saying:

Error: Value cannot be null. Parameter name: clrNamespace (City)

Does anyone have any idea what may be causing this. When I commment out the Label line or when I change to Text="ABC" the error goes away

Upvotes: 0

Views: 1679

Answers (1)

Kedrzu
Kedrzu

Reputation: 653

You did not define your local namespace. You should add namespace: xmlns:local="clr-namespace:City". Change your code to something like this:

 <Frame xmlns="http://xamarin.com/schemas/2014/forms" 
  xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
  xmlns:local="clr-namespace:City"
  x:Class="City.Test">

 <Label x:Name="timer" Text="{Binding Source={x:Static local:MS.TimerSeconds}}" />
        </Grid>

For more information read this article

Upvotes: 3

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