How do you pass parameters from xaml?

Question

I have created my own UserControl "ClockControl", which I initialize through the main window's XAML.

The only problem is that I have to pass a parameter to the constructor of the clock control, and I have no clue of I how I can do that.

This works if I have no parameters:

<myControl:ClockControl></myControl:ClockControl> 

But how can I pass a parameter doing this?

Here is the constructor:

public ClockControl(String city)     {         InitializeComponent();         this.initController();         ......         .....     } 

Thanks in advance.

Answer 1

Your constructor:

public ClockControl(String city) {     InitializeComponent();     this.initController();     //... } 

First of all, if you want to use ClockControl from XAML, then you need a default constructor, means a constructor which doesn't take any parameter. So the above constructor is not going to work.

I would suggest you to define a property with name City, preferably dependency property, and then use it from XAML. Something like this:

public class ClockControl: UserControl     {         public static readonly DependencyProperty CityProperty = DependencyProperty.Register             (                  "City",                   typeof(string),                   typeof(ClockControl),                   new PropertyMetadata(string.Empty)             );          public string City         {             get { return (string)GetValue(CityProperty); }             set { SetValue(CityProperty, value); }         }          public ClockControl()         {             InitializeComponent();         }         //.......... } 

Then you can write this in XAML:

<myControl:ClockControl City="Hyderabad" /> 

Since City is a dependency property, that means you can even do Binding like this:

<myControl:ClockControl City="{Binding Location}" /> 

Hope, that solves your problem!

Answer 2

This is done with the use of DependencyProperty's, however not via the constructor. Just by adding properties to the control itself and using them from the code-behind.

Have a read of the following in regards to DependencyProperty's:

• Dependency Properties Overview
• DependencyProperty Class MSDN
• Why Dependency Properties?

As a visual note, what this will allow you to do is the following, and then use it in the code-behind:

<myControl:ClockControl City="New York"></myControl:ClockControl>