ListView ItemSelected open detail page MVVM

Question

Working in a personal project learning xamarin, got stucked in opening a detailed page about a selected item which I got from an API. The API, it returns an array like this :

{
  "Restaurant": [
 {
   "Address": "Route Bounes Aires",
   "RestaurantID": "1",
   "RestaurantName": "John Doe",
   "City": "Lorem Ipsum"
 }
 {
   "Address": "Route Bounes Aires",
   "RestaurantID": "2",
   "RestaurantName": "John Doe",
   "City": "Lorem Ipsum"
 }]

I managed to bind these informations in a list view using the MVVM pattern. Now I can't seem to open a detailed page for the selcted item. This is what I have so far: restaurantviewmodel.cs

public class RestaurantViewModel : INotifyPropertyChanged
{
    Service _services = new Service();
    List<Restaurant> _restaurant;
    public List<Restaurant> Restaurant
    {
        get { return _restaurant; }
        set
        {
            if (value == _restaurant) return;
            _branches = value;
            OnPropertyChanged();
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;

    public ICommand ReastaurantCommand
    {
        get
        {
            return new Command(async () =>
            {
                Reastaurant = await _apiServices.GetReastaurant();
                await Application.Current.MainPage.Navigation.PushAsync(new ReastaurantPage(_restaurant));
            });
        }
    }        
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

The service.cs

public async Task<List<Reastaurant>> GetReastaurant()
    {

        ListReastaurant restaurant = null;
        try { 
            var client = new HttpClient();
            client.DefaultRequestHeaders.Add("xxx", "xxx");
            client.DefaultRequestHeaders.Add("xxx", xxx);

            HttpContent content = new StringContent("");
            content.Headers.ContentType = new MediaTypeHeaderValue("application/json");

            var response = await client.PostAsync("https:www.here/goes/the/call/to/the/api", content);
            response.EnsureSuccessStatusCode();
            string json = await response.Content.ReadAsStringAsync();
            restaurant = JsonConvert.DeserializeObject<ListReataurantDetails>(json);
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.Message.ToString());
        }
        return restaurant.Restaurant;
    }

The model restaurant.cs

public class Restaurant
{
    public string Address { get; set; }
    public string restaurantID { get; set; }
    public string RestaurantName  { get; set; }
    public string City  { get; set; }
}

The page restaurant.xaml :

<ListView x:Name="restaurantlistview"
              HasUnevenRows="True" ItemSelected="restaurantlistview_ItemSelected">
        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell>
                    <StackLayout Padding="20, 10">
                        <Label  Text="{Binding RestaurantName}"
                                 FontSize="20"
                    </StackLayout>
                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</StackLayout>

The code behind restaurant.xaml.cs

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class Restaurant : ContentPage
{
    public Restaurant(List<Models.Restaurant> restaurant)
    {
        InitializeComponent();
        NavigationPage.SetTitleIcon(this, "icon.png");
        restaurantlistview.ItemsSource = restaurant;
    }
     private async void restaurantlistview_ItemSelected(object sender, SelectedItemChangedEventArgs e)
    {
        await Navigation.PushAsync(new RestaurantSinglePageDetails());
    }
}

How can I approach to this problem? I want to use the details of one restaurant to another page so I can show the address and the city and use these information to do different things. I think it's pretty easy I just didn't grasp well the concept of the mvvm pattern. To clarify I'm not trying to pass all the data to another page, but just trying to access the information about a single item(restaurant). I would really need some help. Thanks guys!

===edit===

public partial class RestaurantSinglePageDetails: ContentPage
{
  public RestaurantSinglePageDetails(Models.Restaurant res)
    {
        InitializeComponent();
        NavigationPage.SetTitleIcon(this, "logosmall.png");
        BindingContext = new RestaurantDetailsViewModel(res);
       //and here I'm supposed to have access to my selected restaurant.
    }
}

restaurantdetailsdviewmodel.cs

public class RestaurantDetailsViewModel : INotifyPropertyChanged
{
    // ==edit==
   Restaurant restaurant;
   public RestaurantDetailsViewModel(Restaurant restaurant)
   {
    this.restaurant = restaurant; // now we can use it in ViewModel
   }
   Service _services = new Service();
   List<Info> _info;
   public List<Info> Info
    {
        get { return _info; }
        set
        {
            if (value == _info) return;
            _info = value; 
            OnPropertyChanged();
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    public ICommand GetInfoCommand
    {
        get
        {
            return new Command(async () =>
            {
                InfoData = await _apiServices.GetInfoData();
                await Application.Current.MainPage.Navigation.PushAsync(new SingleDetailsAboutPrice(InfoData, restaurant));
            });
        }
    }
}

I would like to use the RestaurantID here : SingleDetailsAboutPrice.xaml.cs:

 Restaurant restaurant;
 public SingleDetailsAboutPrice(List<Models.InfoData> data, Restaurant restaurant)
    {
        InitializeComponent();
        this.restaurant = restaurant;
        //can't use the restaurantid here; 
        //some code goes here;
    }

The error

The given key was not present in the dictionary

Answer 1

In your contentPage Restaurant class you should

InitializeComponent();

in the constructor class

XamlCompilation(XamlCompilationOptions.Compile)]
public partial class Restaurant : ContentPage
{
    public Restaurant(List<Models.Restaurant> restaurant)
    {
        InitializeComponent();
        NavigationPage.SetTitleIcon(this, "icon.png");
        restaurantlistview.ItemsSource = restaurant;
    }
    private async void restaurantlistview_ItemSelected(object sender,   SelectedItemChangedEventArgs e)
    {
    //edit
    var restaurant = (Restaurant)sender;
    await Navigation.PushAsync(new RestaurantSinglePageDetails(restaurant));
    }
}

to get item in what you selected:

var restaurant = (Restaurant)sender;

and next you have to create new Page

public partial class RestaurantSinglePageDetails: ContentPage
{
    Restaurant res;
    public RestaurantSinglePageDetails(Restaurant res)
    {
        InitializeComponent();
        this.res = res; 

        //and here you have access to your selected restaurant. 
    }
}

To the res you have access from all class. So you can put this res when you move to another page.

===EDIT===

If I mean correctly, you want to pass RestaurantID to SingleDetailsAboutPrice so you have to pass it to RestaurantDetailsViewModeland then if you click on button put it to SingleDetailsAboutPrice(RestaurantId).

public partial class RestaurantSinglePageDetails: ContentPage
{
    Restaurant res;
    public RestaurantSinglePageDetails(Restaurant res)
    {
        InitializeComponent();
        BindingContext = new RestaurantDetailsViewModel(item); //now you have access to restaurant in your viewModel. In this way you don't need use BindingContext in XAML
        this.res = res; 


        //and here you have access to your selected restaurant. 
    }
}

And now in the RestaurantDetailsViewModel we need to create the constructor with Restaurant

public class RestaurantDetailsViewModel : INotifyPropertyChanged
{
    Service _services = new Service();
    Restaurant restaurant;
    public RestaurantDetailsViewModel(Restaurant restaurant)
    {
        this.restaurant = restaurant; // now we can use it in ViewModel
    }
    List<Info> _info;
    public List<Info> Info
    {
        get { return _info; }
        set
        {
            if (value == _info) return;
            _info = value; 
             OnPropertyChanged();
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    public ICommand GetInfoCommand
    {
        get
        {
            return new Command(async () =>
            {
                InfoData = await _apiServices.GetInfoData();
                await  Application.Current.MainPage.Navigation.PushAsync(new  SingleDetailsAboutPrice(restaurant)); // or if you want u can pass only restaurant.restaurantID.
            });
        }
    }
}

And in SingleDetailsAboutPrice we create constructor with Restaurant or only RestaurantId

public partial class Restaurant : ContentPage
{
    Restaurant restaurant;
    public SingleDetailsAboutPrice(Restaurant restaurant) 
    {
        InitializeComponent();
        this.restaurant = restaurant;
    }

    String restaurantID;
    // if you want only restaurantID
    public SingleDetailsAboutPrice(String restaurantID) 
    {
        InitializeComponent();
        this.restaurantID = restaurantID;
    }
}