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using System;
using Xamarin.Forms.CustomAttributes;
using System.ComponentModel;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Threading.Tasks;
#if UITEST
using Xamarin.UITest;
using NUnit.Framework;
#endif
namespace Xamarin.Forms.Controls
{
[Preserve (AllMembers = true)]
[Issue (IssueTracker.Bugzilla, 27350, "Binding throws Null Pointer Exception when Updating Tab")]
public class Bugzilla27350 : TestContentPage // or TestMasterDetailPage, etc ...
{
protected override void Init ()
{
var btn = new Button { Text = "next main" };
btn.Clicked += async (object sender, EventArgs e) => await Navigation.PushAsync (new MainPage1 ());
Content = btn;
}
class RecipeViewModel
{
public Recipe Recipe { get; set; }
public ObservableCollection<RecipeGroup> RecipeGroups { get; set; }
public async Task LoadRecipesAsync ()
{
var groups = new ObservableCollection<RecipeGroup> ();
groups.Add (new RecipeGroup { Title = "Teste 1" });
groups.Add (new RecipeGroup { Title = "Teste 2" });
groups.Add (new RecipeGroup { Title = "Teste 3" });
groups.Add (new RecipeGroup { Title = "Teste 4" });
groups.Add (new RecipeGroup { Title = "Teste 5" });
groups.Add (new RecipeGroup { Title = "Teste 6" });
groups.Add (new RecipeGroup { Title = "Teste 4" });
groups.Add (new RecipeGroup { Title = "Teste 5" });
groups.Add (new RecipeGroup { Title = "Teste 6" });
RecipeGroups = groups;
}
}
class Recipe
{
public string ID { get; set; }
public string Title { get; set; }
public string Subtitle { get; set; }
public string Description { get; set; }
public string ImagePath { get; set; }
public string TileImagePath { get; set; }
public int PrepTime { get; set; }
public string Directions { get; set; }
public List<string> Ingredients { get; set; }
}
class RecipeGroup : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged (string caller)
{
var handler = PropertyChanged;
if (handler != null) {
handler (this, new PropertyChangedEventArgs (caller));
}
}
public string ID { get; set; }
public string Title {
get{ return _title; }
set {
_title = value;
OnPropertyChanged ("Title");
}
}
string _title;
public string Subtitle { get; set; }
public string ImagePath { get; set; }
public string GroupImagePath { get; set; }
public string Description { get; set; }
public List<Recipe> Recipes { get; set; }
}
class MainPage1 : TabbedPage
{
public MainPage1 ()
{
ItemTemplate = new DataTemplate (() => {
var page = new ContentPage ();
page.SetBinding (TitleProperty, new Binding ("Title"));
var btn = new Button { Text = "change", Command = new Command (() => {
(page.BindingContext as RecipeGroup).Title = "we changed";
})
};
var btn1 = new Button { Text = "null", Command = new Command (() => {
(page.BindingContext as RecipeGroup).Title = null;
})
};
page.Content = new StackLayout { Children = { btn, btn1 } };
return page;
});
SetBinding (ItemsSourceProperty, new Binding ("RecipeGroups"));
}
protected override async void OnAppearing ()
{
base.OnAppearing ();
if (BindingContext == null)
BindingContext = await GetRecipeViewModelAsync ();
}
RecipeViewModel _rvm;
public async Task<RecipeViewModel> GetRecipeViewModelAsync ()
{
if (_rvm == null) {
_rvm = new RecipeViewModel ();
} else {
_rvm.RecipeGroups.Clear ();
}
await _rvm.LoadRecipesAsync ();
return _rvm;
}
}
}
}
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