LazyLoading + pass params to view model of TabViewItems MVVM first approach.

[LeoJHarris]

Hi all, I am trying to implement LazyView on my TabViewItem. My Xamarin project is using Prism and I have a main page that contains my TabView. I would like my TabViewItems to utilize LazyView.

My main page is passed a parameter which needs to be presented to the ViewModels of the tab items as there are some methods that get called when loaded, how can I pass and provide the paramater to the TabViewItems in the VM that are wrapped with LazyView and do this once View is Loaded? @pictos

Something like the prism equivalent is what I need, I cannot use regions in Templated View and doesn't provide lazy loading hence I am keen to get this working:

            if (parameters.ContainsKey("customerid"))
            {
                _regionManager.RequestNavigate("RefillsRegion", "RefillsView", RegionNavigationCallback, new NavigationParameters
                        {
                            { "customerid", parameters.GetValue<long>("customerid") }
                        });
            }
        }

Thanks in advance

[pictos]

@LeoJHarris I moved this to the Discussion session since this fits better. So I don't have too much experience with prism and other MVVM frameworks. Are you able to provide a simple sample project that I can play with and see if I find a good solution?

I believe that you will need to create your own LazyView implementation with those extra features

[LeoJHarris]

@pictos thanks again for the time taken to help me on this, that solution works good for me. This is part of my actual application now and just wondering to keep this as lazy loading am I able to execute a command on my tab view model that will take a value and do some tasks required within the view model i.e. calling some API's or do I just set a property on the view model and then wait for isLoaded to be called and execute some code with the value?

Something like the below where once the page is initialized with the parameter I can call RefreshTabViewModelContentAsync on the view model for which the tab view is being lazy loaded.

public override void Initialize(INavigationParameters parameters)
        {
            base.Initialize(parameters);

            if (parameters.ContainsKey("customerid"))
            {
                RefillsTabViewModel.RefreshRefillsCommand.Execute(customerid);
                HistoryTabViewModel.RefreshScriptHistoryCommand.Execute(customerid);
            }
        }

Should the refresh commands be getting called when isLoaded is true?

[pictos]

@LeoJHarris Sorry for the late reply... What's the behavior that you want in the UI? If I remember well, the VM will be created before the View (LazyView), so when the View is rendered the RefreshCommands are already triggered. So this behavior is causing any issue?

[LeoJHarris]

@pictos sorry for the really late response on this I think its all sorted.

[pictos]

@LeoJHarris it's fine. Can I close this discussion?

[LeoJHarris]

@pictos yup conversation resolved 😄

[pictos]

Sample.zip

@LeoJHarris

[HASSANRAGAI]

@LeoJHarris
I don't know if you still want to solve it I had the same issue and I edited the @pictos solution and you don't have to set the ViewModel manual
see this repo and feel free to help me if there are any edits

https://github.com/ZHEAISNSAABN/ZhEaIsNsAaBn.Xamarin/tree/master/Src/ZhEaIsNsAaBn.Xamarin/LazyView

[LeoJHarris]

@HASSANRAGAI great work I had a brief look at the setup and looks great.

[HASSANRAGAI]

@LeoJHarris thnx hope it will help other developers