在基本视图模型中定义命令

Question

We would like define some button be visible in every page for a set of users. We defined button as control template for view and called out it in the pages that require them to be displayed.

<Button ImageSource="home_footer.png" BackgroundColor="Transparent" HorizontalOptions="FillAndExpand" 
        Command="{TemplateBinding BindingContext.HomeCommand}"/>

Here command is selected according to the binding context, ie corresponding view model. Command need to written multiple times. I thought of including the command in base view model so that it needs to written only once. Is there any option for implementing this option. Thanks in advance.

Answer 1

In your BaseViewModel add a command

    public ICommand HomeCommand { get; set; }

In your base ContentPage add a bindable property that supplies you this command:

   public ICommand Command
    {
        get => (ICommand)GetValue(CommandProperty);
        set => SetValue(CommandProperty, value);
    }

    public object CommandParameter
    {
        get => GetValue(CommandParameterProperty);
        set => SetValue(CommandParameterProperty, value);
    }


    public static readonly BindableProperty CommandProperty = BindableProperty.Create(
        nameof(Command),
        typeof(ICommand),
        typeof(ClassName),
        null
        );

    public static readonly BindableProperty CommandParameterProperty = BindableProperty.Create(
        nameof(CommandParameter),
        typeof(object),
        typeof(ClassName),
        null
        );

Supply a command to this property from the ContentPage

<base:CustomContentPage ....
Command="{Binding HomeCommand}">

Set it to your Button something like:

You can give it a better name to explain the behaviour,

Goodluck!

Feel free to get back if you have queries!