Actual Date and Time bind to a Label

Question

Hello,

 

I'd like to bind the actual date and time to a Label. I tried the following code, but it doesn't work. Does anyone now why?

 

Code Snippet

<Window ...

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:src="clr-namespace:System;assembly=mscorlib">

<Window.Resources>

<ObjectDataProvider x:Key="date" ObjectType="{x:Type src:DateTime}" MethodName="Now"/>

</Window.Resources>

 

....

<Label Content="{Binding Source={StaticResource date}, Mode=OneWay}"/>

 

Why is it not working? Did I miss something or is my idea totally wrong?

 

Thanks

 

Chris

Answer 1

Hi Chris,

 

Now isn't a method, it's a property:

 

Code Snippet

<Window.Resources>

<ObjectDataProvider x:Key="date" ObjectType="{x:Type src:DateTime}"/>

</Window.Resources>

<Label Content="{Binding Source={StaticResource date},Path=Now,Mode=OneWay}"/>

 

But if you do it this way, the date is just initialized and never updated. Is this that what you want?

Answer 2

No,

 

i want that it will be updated all the time automatically. I thought I can do this with databinding. Isn't that right?

How should I do it instead?

 

 

Answer 3

Hi Chris,

 

the problem is that DateTime.Now has no mechanism for change-notification.

So you need a custom solution.

 

I would create an extra class that has only a now property and implements INotifyPropertyChanged. It could look like this:

 

Code Snippet

public class NotifyingDateTime:INotifyPropertyChanged

{

public event PropertyChangedEventHandler PropertyChanged;

private DateTime _now;

public NotifyingDateTime()

{

_now = DateTime.Now;

DispatcherTimer timer = new DispatcherTimer();

timer.Interval = TimeSpan.FromMilliseconds(100);

timer.Tick += new EventHandler(timer_Tick);

timer.Start();

}

public DateTime Now

{

get{return _now;}

private set

{

_now = value;

if(PropertyChanged!=null)

PropertyChanged(this,new PropertyChangedEventArgs("Now"));

}

}

void timer_Tick(object sender, EventArgs e)

{

Now = DateTime.Now;

}

}

 

In your XAML-File you could then just bind to the Now-Property of this class and will get always the current date and time.

If you need to show a different TimeFormat, you could use a ValueConverter to do that:

 

Code Snippet

<Window x:Class="MyApp.Window1"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:local="clr-namespace:MyApp"

Title="MyApp" Height="300" Width="300"

>

<Window.Resources>

<local:NotifyingDateTime x:Key="notifyingDate"/>

</Window.Resources>

<Label Content="{Binding Source={StaticResource notifyingDate},Path=Now}"/>

</Window>

 

 

Thomas

Answer 4

 Hello Thomas,

 

yeah it works fine. Thanks. I just needed to change something a bit. Just if someone wants to use it later as well:

 

Code Snippet

<Window.Resources>

<ObjectDataProvider x:Key="notifyingDate" ObjectType="{x:Type local:NotifyingDateTime}"/>

</Window.Resources>

 

Thanks a lot.

 

Cheers

 

Chrsi