c# - How to implement a navigation button in shared application resources?

Question

I'm currently trying to create a simple app that pulls data from an API I made and displays it in a list. You are then supposed to be able to click the list items to be navigated to a detailed view page with an image viewer etc. For that to work I need to navigate to a page called PlanViewer.xaml (currently only available for the Windows Phone app part, will do for both though).

For my list to work I built the following data template in my shared App.xaml:

    <DataTemplate x:Key="PlanDataTemplate">
        <StackPanel Orientation="Horizontal">
            <Button Name="NavigatePlan" Tag="{Binding FilePath}">
                <StackPanel>
                    <TextBlock Style="{StaticResource SubheaderTextBlockStyle}" Text="{Binding Name}" />
                    <TextBlock Style="{StaticResource TitleTextBlockStyle}" Text="{Binding LastUpdate}" />
                </StackPanel>
            </Button>
        </StackPanel>
    </DataTemplate>

I apply it in my MainPage.xaml as shown here:

<ItemsControl x:Name="PlanList" ItemTemplate="{StaticResource PlanDataTemplate}" ItemsSource="{Binding PlanItems}" >
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
</ItemsControl>

I can't bind any events to the button in the App.xaml, so I think I need to use an ICommand interface. I might also have a much more fundamental mistake in how I built this thing so far.

TL;DR for my goal: I want to adjust the datatemplate so that every button links to a page PlanViewer.xaml with an argument describing which plan is supposed to be shown (e.g. ID or file path).

Answer 1

This is an Universal App solution. It's can view as basically a tutorial on Model, View,and ViewModel.

I don't know what UI Element you want to use, but for this I going to pick a one that is supported in both Windows 8.1 and WP 8.1. The ListView, so in both Project's MainPage.xaml lets define that.

---

<ListView x:Name="myListView">
    <ListView.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBlock Text="{Binding Artist}"></TextBlock>
                <TextBlock Text="{Binding Song}"></TextBlock>
                <Button Command="{Binding ElementName=myListView, Path=DataContext.SimpleCommand}"
                        CommandParameter="{Binding Extra}"
                        x:Name="mybutton" Width="200" Height="50" FontFamily="Global User Interface" Content="Click Me"/>
            </StackPanel>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

As you can see, I databinded the Button with a Command and a CommandParameter. The command is the function in the ViewModel that I want to execute when the user clicks the button. The CommandParameter is a object you want to pass to your Command function. In your case, your TAG.

---

Namespaces

using System.Collections.ObjectModel;              // ObservableCollection
using System.Windows.Input;                        // ICommand

---

Now lets defined a Command (Should be part of the Shared Project)

public class MySimpleCommand : ICommand
{
    public void Execute(object parameter)
    {
        // do stuff based off your tags
        string tag = parameter as string;
        if(tag == "WHATEVER_YOU_WANT")
        {
        }

        // void of the trigger libraries, lets make this simple
        // navigate to your page
        Frame rootFrame = Window.Current.Content as Frame;
        rootFrame.Navigate(typeof(YOUR_PAGE));

    }
    public bool CanExecute(object parameter)
    {
        return true;
    }
    public event EventHandler CanExecuteChanged;
}

---

Now lets setup a simple model (Should be part of the Shared Project)

public class sample_model
{
    public sample_model(string artist, string song, string extra = "")
    {
        this.Artist = artist;
        this.Song = song;
        this.Extra = extra;
    }

    public string Artist { get; set; }
    public string Song { get; set; }
    public string Extra { get; set; }         // this is your tag
}

---

Now lets setup a ViewModel for our ListView(s) to use. (Should be part of the Shared Project)

public class sample_viewmodel
{
    public sample_viewmodel()
    {
        this.DataSource = CreateData();

        this.SimpleCommand = new MySimpleCommand();  // create the command
    }

    // create a static list for our demo
    private ObservableCollection<sample_model> CreateData()
    {
        ObservableCollection<sample_model> my_list = new ObservableCollection<sample_model>();
        my_list.Add(new sample_model("Faith + 1", "Body of Christ", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Christ Again", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "A Night With the Lord", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Touch Me Jesus", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "I Found Jesus (With Someone Else)", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Savior Self", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Christ What a Day", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Three Times My Savior", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Jesus Touched Me", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Lord is my Savior", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "I Wasn't Born Again Yesterday", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Pleasing Jesus", "A Track"));
        my_list.Add(new sample_model("Faith + 1", "Jesus (Looks Kinda Hot)", "A Track"));
        my_list.Add(new sample_model("Butters", "What What", "B Track"));
        return my_list;            
    }

    public ICommand SimpleCommand { get; set; }
    public ObservableCollection<sample_model> DataSource{ get; set; }

}

---

And finally, lets link the ListView to our ViewModel which should bind the "Artist, Song, and Button (Command & CommandParamters)". I usually do this in each Page's Load function.

private void Page_Loaded(object sender, RoutedEventArgs e)
{
    sample_viewmodel viewmodel = new sample_viewmodel();  // create the view model
    myListView.DataContext = viewmodel;                   // set the datacontext (this will link the commands)
    myListView.ItemsSource = viewmodel.DataSource;        // set the ItemsSource, this will link the Artist,Songs
}

---

There you have it, each time the user clicks on the button no matter what platform it will perform the Command function.

Sample Screenshot