Answers

• LandLu Member, Xamarin Team Xamurai

  January 14 Accepted Answer

  The OrderDetailsViewModel should be included in the TabbedPageViewModel as a property, then when you pass parameters to TabbedPageViewModel, OrderDetailsViewModel could also notify the value.

  The custom TabbedPage's Xaml:

  <TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
               xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
               x:Class="Demo.MyTabbedPage"
               xmlns:local="clr-namespace:Demo">
    <!--Pages can be added as references or inline-->
    <local:OrderDetailsView Title="Tab 1" BindingContext="{Binding OrderDetailsViewTab}"/>
    <local:SecPage Title="Tab 2" BindingContext="{Binding SecViewTab}"/>
    <local:ThirdPage Title="Tab 3" BindingContext="{Binding ThirdViewTab}"/>
  </TabbedPage>
  

  code behind for TabbedPageViewModel:

  public class MyTabbedPageViewModel
  {
      public OrderDetailsViewModel OrderDetailsViewTab { set; get; }
      public SecViewModel SecViewTab { set; get; }
      public ThirdViewModel ThirdViewTab { set; get; }
  
      public MyTabbedPageViewModel(string orderID)
      {
          OrderDetailsViewTab = new OrderDetailsViewModel { ... };
          //...
      }
  }
  

  When you want to navigate to this tabbed page, you could pass parameters like:

  var tabbedPage = new MyTabbedPage();
  tabbedPage.BindingContext = new MyTabbedPageViewModel(...);
  Navigation.PushAsync(tabbedPage);
  

  5
• Reed Member ✭✭

  January 14 edited January 14

  Thanks for the answer

  But what if my OrderDetailsViewModel has some services, that needs to be injected?

  Should I resolve the dependencies in MyTabbedPageViewModel?

  Or when I'm navigating to MyTabbedPageViewModel from OrdersViewModel, the OrdersViewModel should get the services through constructor injection and pass it down to MyTabbedPageViewModel constructor, which it will again forward to OrderDetailsViewModel constructor?

  It would be perfect if I could use InitializeAsync method that comes from ViewModelBase to pass the orderID instead of using the constructor. I use this book as a reference for my architecture:

  https://docs.microsoft.com/en-us/xamarin/xamarin-forms/enterprise-application-patterns/

  https://github.com/dotnet-architecture/eShopOnContainers/tree/1b7200791931f33c94206822a69644ca820bb0dc/src/Mobile/eShopOnContainers/eShopOnContainers.Core

  0
• LandLu Member, Xamarin Team Xamurai

  January 16

  But what if my OrderDetailsViewModel has some services, that needs to be injected?

  You can expand my sample constructor to inject other services you want to use:

  public MyTabbedPageViewModel(string orderID, IOrderService orderService, other services...)
  {
      _orderService = orderService;
      ...
      OrderDetailsViewTab = new OrderDetailsViewModel();
      // Do what you want here
      // Just pass the Id to OrderDetailsViewModel
      OrderDetailsViewTab.OrderID = orderID;
  }
  

  You can also record this ID via a private proerty of MyTabbedPageViewModel, then you can pass this id to OrderDetailsViewModel when you want to do that instead of setting it to OrderDetailsViewTab directly.

  0