Xamarin Forms - CommandParameter - How to pass custom object via XAML?

Question

I have a command in a view model called Add and it currently takes in one parameter called Result. I now need more data passed into the command and that is the IsToggled property value of the Switch control.

So if I have the following class:

public class ResultData
{
    public string Result { get; set; }
    public bool IsToggled { get; set; }
}

And a snippet of the XAML in question:

 <Switch IsToggled="false" ThumbColor="Black" OnColor="LimeGreen" HorizontalOptions="End" VerticalOptions="Center" >
    <Switch.Behaviors>
         <behaviours:EventToCommandBehavior EventName="Toggled"                                                            
           Command="{Binding BindingContext.Add, Source={x:Reference 
              MyPageContent}}" 
           CommandParameter="{Binding Result}" />
    </Switch.Behaviors>
 </Switch>

What is the XAML syntax to pass Result & IsToggled using the CommandParameter? I am open to other approaches if you feel that this not the right way to do it.

Ali Ahmad · Accepted Answer · 2020-06-08 11:40:13Z

5

You can do it just set your switch BindingContext to Result and pass your switch to CommandParameter as parameter and from that parameter you can get any property of switch.

<Switch IsToggled="false" ThumbColor="Black" OnColor="LimeGreen" HorizontalOptions="End" VerticalOptions="Center" BindingContext="{Binding Result}" x:Name="switch">
    <Switch.Behaviors>
         <behaviours:EventToCommandBehavior EventName="Toggled"                                                            
           Command="{Binding BindingContext.Add, Source={x:Reference 
              MyPageContent}}" 
           CommandParameter="{Binding Source={x:Reference switch}}" />
    </Switch.Behaviors>
</Switch>

answered Jun 8, 2020 at 11:40

Ali Ahmad

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Comments

Jarvan Zhang · Accepted Answer · 2020-06-08 03:05:39Z

How to pass custom object via XAML? What is the XAML syntax to pass Result & IsToggled using the CommandParameter?

The CommandParameter is type of object, we could pass a class object value as the parameter. To pass both the Result & IsToggled, try to set a ResultData object as the CommandParameter and get the two properties in code behind.

I create a basic demo to test the function, you could refer to the code.

Page.xaml

<Label Text="Welcome to Xamarin.Forms!"
       HorizontalOptions="CenterAndExpand">
    <Label.GestureRecognizers>
        <TapGestureRecognizer Command="{Binding TappedCommand}" CommandParameter="{Binding _Parameter}"/>
    </Label.GestureRecognizers>
</Label>

Page.xaml.cs

public partial class Page4 : ContentPage
{
    public Page4()
    {
        InitializeComponent();

        BindingContext = new Model_4();
    }
}

Model class

public class Model_4
{
    public TheParameter _Parameter { get; set; }

    public ICommand TappedCommand { private set; get; }

    public Model_4()
    {
        TappedCommand = new Command(OnTapped);
        _Parameter = new TheParameter { Property_1 = "Property_1", Property_2 = "Property_2" };
    }

    private void OnTapped(object obj)
    {
        var theParameter = obj as TheParameter;
        Console.WriteLine(theParameter.Property_1);
        Console.WriteLine(theParameter.Property_2);
    }
}

public class TheParameter
{
    public string Property_1 { get; set; }
    public string Property_2 { get; set; }
}

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