Develop Reference

Editing copies of an ObservableCollection's Object without editing the ObservableCollection

I have a WPF form that I want to use to manipulate a database table. To get the data out of the database I use Entity Framework Core. I try to follow the MVVM pattern.
So I have a Model called Employee with a number of string properties like Firstname and so on.
The form has a ListView that shows an ObservableCollection of Employee. Further I have a number of TextBoxes to display and manipulate the properties of single Employee objects. The selectedMemberPath of the ListView is bound to a property SelectedEmployee. The setter of SelectedEmployee than copies it's own properties to EditedEmployee. The TextBoxes are bound to EditedEmployee. The idea is, that I don't want to directly edit the ObservableCollection. This should only happen if a save button is clicked.
This is my view model.
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.ChangeTracking;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using XdcCore.Models;
using XdcCore.ViewModels.Commands;
namespace XdcCore.ViewModels
{
class EmployeeEditorVM : List<Employee>, INotifyPropertyChanged
{
public EmployeeSaveCommand EmployeeSaveCommand { get; set; }
public EmployeeEditorVM()
{
EmployeeSearch();
EmployeeSaveCommand = new EmployeeSaveCommand(this);
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private string employeeSearchText;
public string EmployeeSearchText
{
get { return employeeSearchText; }
set
{
employeeSearchText = value;
OnPropertyChanged("EmployeeSearch");
EmployeeSearch();
}
}
private Employee selectedEmployee;
public Employee SelectedEmployee
{
get { return selectedEmployee; }
set
{
selectedEmployee = value;
OnPropertyChanged("SelectedEmployee");
EditedEmployee = SelectedEmployee;
}
}
private Employee editedEmployee;
public Employee EditedEmployee
{
get { return editedEmployee; }
set
{
editedEmployee = value;
OnPropertyChanged("EditedEmployee");
}
}
private ObservableCollection<Employee> employees;
public ObservableCollection<Employee> Employees
{
get { return employees; }
set
{
employees = value;
OnPropertyChanged("Employees");
}
}
public void EmployeeSearch()
{
using (var context = new XdcContext())
{
if (employeeSearchText != null)
{
var _employees = context.Employee
.Where(x => x.Firstname.Contains(employeeSearchText));
Employees = new ObservableCollection<Employee>(_employees);
}
else
{
var _employees = context.Employee.Select(x => x);
Employees = new ObservableCollection<Employee>(_employees);
}
}
}
public void EmployeeSave()
{
using (var context = new XdcContext())
{
var entity = context.Employee.First(x => x.IdEmployee == SelectedEmployee.IdEmployee);
{
entity.Firstname = SelectedEmployee.Firstname;
entity.Lastname = SelectedEmployee.Lastname;
entity.Initials = SelectedEmployee.Initials;
context.SaveChanges();
}
EmployeeSearch();
}
}
}
}
this is my View:
<Window
x:Class="XdcCore.Views.Editors.EmployeeEditor"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:XdcCore.Views.Editors"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:vm="clr-namespace:XdcCore.ViewModels"
Title="Employee"
Width="800"
Height="450"
mc:Ignorable="d">
<Window.Resources>
<vm:EmployeeEditorVM x:Key="vm" />
</Window.Resources>
<Grid DataContext="{StaticResource vm}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="300" />
<ColumnDefinition Width="115*" />
<ColumnDefinition Width="277*" />
</Grid.ColumnDefinitions>
<!-- left column -->
<Border BorderBrush="DarkGray" BorderThickness="1">
<Grid Grid.Column="0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
<RowDefinition Height="aUTO" />
</Grid.RowDefinitions>
<Label
Grid.Row="0"
Margin="3,3,3,3"
Content="Filter:" />
<TextBox
x:Name="TextBoxSearch"
Grid.Row="1"
Height="25"
Margin="3,0,3,3"
HorizontalContentAlignment="Left"
VerticalContentAlignment="Center"
Text="{Binding EmployeeSearchText, Mode=TwoWay}" />
<ListView
x:Name="ListViewOverview"
Grid.Row="2"
Margin="3,0,3,0"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
ItemsSource="{Binding Employees, Mode=OneWay}"
SelectedItem="{Binding SelectedEmployee, Mode=OneWayToSource}">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Initials}" />
<TextBlock Text=" : " />
<TextBlock Text="{Binding Firstname}" />
<TextBlock Text=" " />
<TextBlock Text="{Binding Lastname}" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Grid Grid.Row="3">
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Button
x:Name="ButtonDelete"
Grid.Column="0"
Height="25"
Margin="3,3,3,3"
Content="Delete"
IsEnabled="False" />
<Button
x:Name="ButtonNew"
Grid.Column="1"
Height="25"
Margin="3,3,3,3"
Content="Add New ..."
IsEnabled="True" />
</Grid>
</Grid>
</Border>
<!-- right Column -->
<Grid Grid.Column="1" Grid.ColumnSpan="2">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<!-- right column, first row -->
<Border
Grid.Row="0"
BorderBrush="DarkGray"
BorderThickness="1">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="25" />
<RowDefinition Height="25" />
<RowDefinition Height="25" />
<RowDefinition Height="25" />
<RowDefinition Height="25" />
<RowDefinition Height="25" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100" />
<ColumnDefinition Width="200" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Label
Grid.Row="0"
Grid.Column="0"
HorizontalAlignment="Right"
Content="First Name" />
<Label
Grid.Row="1"
Grid.Column="0"
HorizontalAlignment="Right"
Content="Last Name" />
<Label
Grid.Row="2"
Grid.Column="0"
HorizontalAlignment="Right"
Content="Initials" />
<Label
Grid.Row="3"
Grid.Column="0"
HorizontalAlignment="Right"
VerticalContentAlignment="Center"
Content="ID" />
<Label
Grid.Row="4"
Grid.Column="0"
HorizontalAlignment="Right"
VerticalContentAlignment="Center"
Content="RCU" />
<Label
Grid.Row="5"
Grid.Column="0"
HorizontalAlignment="Right"
VerticalContentAlignment="Center"
Content="RCT" />
<TextBox
x:Name="TextBoxFirstName"
Grid.Row="0"
Grid.Column="1"
Margin="0,3,3,3"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
VerticalContentAlignment="Center"
Text="{Binding EditedEmployee.Firstname, Mode=TwoWay}" />
<TextBox
x:Name="TextBoxLastName"
Grid.Row="1"
Grid.Column="1"
Margin="0,3,3,3"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
VerticalContentAlignment="Center"
Text="{Binding EditedEmployee.Lastname, Mode=TwoWay}" />
<TextBox
x:Name="TextBoxInitials"
Grid.Row="2"
Grid.Column="1"
Margin="0,3,3,3"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
VerticalContentAlignment="Center"
Text="{Binding EditedEmployee.Initials, Mode=TwoWay}" />
<TextBox
x:Name="TextBoxId"
Grid.Row="3"
Grid.Column="1"
Margin="0,3,3,3"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
VerticalContentAlignment="Center"
IsReadOnly="True" />
<TextBox
x:Name="TextBoxRCU"
Grid.Row="4"
Grid.Column="1"
Margin="0,3,3,3"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
VerticalContentAlignment="Center"
IsReadOnly="True" />
<TextBox
x:Name="TextBoxRCT"
Grid.Row="5"
Grid.Column="1"
Margin="0,3,3,3"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Left"
VerticalContentAlignment="Center"
IsReadOnly="True" />
</Grid>
</Border>
<Grid Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Button
x:Name="ButnSave"
Grid.Column="1"
Width="76"
Height="25"
Margin="60,3,60,0"
HorizontalAlignment="Center"
VerticalAlignment="Top"
Command="{Binding EmployeeSaveCommand}"
Content="Save"
IsEnabled="True" />
</Grid>
<!-- Add new -->
</Grid>
</Grid>
</Grid>
</Window>
In other words: I want to click on an item in the list view, it's details are shown in the text boxes. I can change the text in the text boxes but the changes are not applied to the observable collection (or even database) until I click "save". The problem is, that exactly that happens: when I edit text in the text boxes the changes are also shown in the list view. And I can#t see why.

So, I got the concept of "copy vs point" of a variable wrong.
I had two solutions for my problem.
To my Employee model I added the method Copy:
public partial class Employee
{
public int IdEmployee { get; set; }
public string Initials { get; set; }
public string Firstname { get; set; }
public string Lastname { get; set; }
public string Rcu { get; set; }
public DateTime Rct { get; set; }
public Employee Copy()
{
return (Employee)this.MemberwiseClone();
}
}
Then I Changed my ViewModel so that EditedEmployee is a copy of SelectedEmployee
private Employee selectedEmployee;
public Employee SelectedEmployee
{
get { return selectedEmployee; }
set
{
selectedEmployee = value;
OnPropertyChanged("SelectedEmployee");
if (SelectedEmployee != null)
{
EditedEmployee = SelectedEmployee.Copy();
}
}
}
private Employee editedEmployee;
public Employee EditedEmployee
{
get { return editedEmployee; }
set
{
editedEmployee = value;
OnPropertyChanged("EditedEmployee");
}
}
The problem with this approach is, that if I mess around with the database and then need to run Scaffold-DbContext (I prefer the code-first approach of EFC) again, I would have to modify all models again. A solution to that might be some a second, modified Model that inherits from the original Model and then adds the Copy method.
My second approach is to bind the ListView via SelectedIndex instead of SelectedItem.
<ListView
...
ItemsSource="{Binding Employees, Mode=OneWay}"
SelectedIndex="{Binding SelectedItemIndex, Mode=TwoWay}">
In the ViewModel this is then represented by an int property. If this int is set (and >= 0) Employee gets copied EmployeeWorkingCopy. Furthermore if EmployeeWorkingCopy is set a single Employee dubbed EditedEmployee is set as the Employee of the working copy with the selected index.
private int selectedItemIndex;
public int SelectedItemIndex
{
get { return selectedItemIndex; }
set
{
selectedItemIndex = value;
if (SelectedItemIndex >= 0)
EmployeesWorkingCopy = new ObservableCollection<Employee>(Employees);
}
}
private Employee editedEmployee;
public Employee EditedEmployee
{
get { return editedEmployee; }
set
{
editedEmployee = value;
OnPropertyChanged("EditedEmployee");
}
}
private ObservableCollection<Employee> employeesWorkingCopy;
public ObservableCollection<Employee> EmployeesWorkingCopy
{
get { return employeesWorkingCopy; }
set
{
employeesWorkingCopy = value;
EditedEmployee = EmployeesWorkingCopy[SelectedItemIndex];
}
}
Thanks a lot for pointing out my misconception.

How to databind a class object to a ViewCell?

I need to databind a class object to a custom ViewCell. I used the {Binding propName} for the fields on the controls inside the ViewCell. I'm not sure if I am adding the ViewCell correctly since it shows as [AppName.GridView] and does not show the control I built. What is the correct way to bind this control with the custom class?
<?xml version="1.0" encoding="UTF-8"?>
<ViewCell xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
Height="50">
<Frame HeightRequest="50" Padding="0" Margin="1" BorderColor="blue" CornerRadius="4" BackgroundColor="lightBlue">
<Grid BindingContext="Binding local:di" >
<Grid.RowDefinitions >
<RowDefinition Height="34"/>
<RowDefinition Height="40"/>
</Grid.RowDefinitions>
<Grid Grid.Row="0" BackgroundColor="Transparent" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="3"/>
<ColumnDefinition Width="10*" />
<ColumnDefinition Width="5*" />
<ColumnDefinition Width="5*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions >
<RowDefinition Height="40"></RowDefinition>
</Grid.RowDefinitions>
<Button x:Name="btnItem" Text="{Binding itemName}" Clicked="BtnClicked" Padding="0" Grid.Column="1" FontSize="20" />
<Label x:Name="lbAmt" Text="{Binding amt}" Grid.Column="2" Margin="2" VerticalTextAlignment="Center" HorizontalTextAlignment="End" FontSize="20" BackgroundColor="lightBlue" />
<Label x:Name="lbType" Text="{Binding amtType}" Grid.Column="3" Margin="2" VerticalTextAlignment="Center" FontSize="20" BackgroundColor="lightBlue" />
</Grid>
...
</Grid>
</Frame>
The code to add the object.
DItem di = new DItem() { itemName = "someName", amt = 1, amtType = xf };
GridItems gi = new GridItems() { di = di };
ObservableCollection<GridItems> lv = new ObservableCollection<GridItems>();
lv.Add(gi);
lvItems.ItemsSource = lv;

If you want to achieve the databinding with listview(MVVM),
Here is running screenshot.
First of all, you can create a model DItem.I achieve the INotifyPropertyChanged interface, layout will changed when the value was changed
public class DItem: INotifyPropertyChanged
{
string _itemName;
public string itemName
{
set
{
if (_itemName != value)
{
_itemName = value;
OnPropertyChanged("itemName");
}
}
get
{
return _itemName;
}
}
int _amt;
public int amt
{
set
{
if (_amt != value)
{
_amt = value;
OnPropertyChanged("amt");
}
}
get
{
return _amt;
}
}
string _amtType;
public string amtType
{
set
{
if (_amtType != value)
{
_amtType = value;
OnPropertyChanged("amtType");
}
}
get
{
return _amtType;
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Then, achieve the ModelView.DItemViewModel, We do not need create GridItems just add the DItem to the ObservableCollection<DItem>
public class DItemViewModel
{
public ObservableCollection<DItem> lv { get; set; }
public DItemViewModel()
{
DItem di = new DItem() { itemName = "someName", amt = 1, amtType = "xf" };
lv = new ObservableCollection<DItem>();
lv.Add(di);
}
}
Here is layout of listview. add the ItemsSource="{Binding lv}" for listview.
<ListView ItemsSource="{Binding lv}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame HeightRequest="50" Padding="0" Margin="1" BorderColor="blue" CornerRadius="4" BackgroundColor="lightBlue">
<Grid >
<Grid.RowDefinitions >
<RowDefinition Height="34"/>
<RowDefinition Height="40"/>
</Grid.RowDefinitions>
<Grid Grid.Row="0" BackgroundColor="Transparent" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="3"/>
<ColumnDefinition Width="10*" />
<ColumnDefinition Width="5*" />
<ColumnDefinition Width="5*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions >
<RowDefinition Height="40"></RowDefinition>
</Grid.RowDefinitions>
<Button x:Name="btnItem" Text="{Binding itemName}" Clicked="btnItem_Clicked" Padding="0" Grid.Column="1" FontSize="20" />
<Label x:Name="lbAmt" Text="{Binding amt}" Grid.Column="2" Margin="2" VerticalTextAlignment="Center" HorizontalTextAlignment="End" FontSize="20" BackgroundColor="lightBlue" />
<Label x:Name="lbType" Text="{Binding amtType}" Grid.Column="3" Margin="2" VerticalTextAlignment="Center" FontSize="20" BackgroundColor="lightBlue" />
</Grid>
</Grid>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
And here is background code for the listview.
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
BindingContext = new DItemViewModel();
}
private void btnItem_Clicked(object sender, EventArgs e)
{
}
}
Here are helpful articles about MVVM in Xamarin forms.
https://almirvuk.blogspot.com/2017/02/xamarinforms-listview-simple-mvvm.html
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/xaml/xaml-basics/data-bindings-to-mvvm

Can`t bind entry and property in two way mode

Try to create simple app that will add items to the list. Have problems with binding entries with properties in ViewModel.
Here is my xaml:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:viewModels="clr-namespace:MyScoreDemo.ViewModels;assembly=MyScoreDemo"
x:Class="MyScoreDemo.Views.ClubListPage">
<StackLayout
Padding="15"
Spacing="10">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Label Text="Name:" Grid.Row="0" Grid.Column="0"/>
<Entry x:Name="EntryName" Text="{Binding Club.Name, Mode=OneWayToSource}" Grid.Row="0" Grid.Column="1"/>
<Label Text="Country:" Grid.Row="1" Grid.Column="0"/>
<Entry x:Name="EntryCountry" Text="{Binding Club.Country, Mode=OneWayToSource}" Grid.Row="1" Grid.Column="1"/>
<Button Text="Add" Command="{Binding AddCommand}" CommandParameter="{x:Reference EntryName}"
Grid.Row="2" Grid.ColumnSpan="2" Grid.Column="0" />
</Grid>
<ListView ItemsSource="{Binding Clubs}"
Margin="5">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Label Text="{Binding Path=Name}"/>
<Label Text="{Binding Path=Country}" Grid.Column="1"/>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<StackLayout.BindingContext>
<viewModels:ClubListViewModel/>
</StackLayout.BindingContext>
</StackLayout>
And ViewModel code:
private Club _club;
public ICommand AddCommand { get; set; }
public ICommand RemoveCommand { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
public ObservableCollection<Club> Clubs { get; set; }
public ClubListViewModel()
{
AddCommand = new Command(AddClub);
RemoveCommand = new Command(RemoveClub);
Clubs = new ObservableCollection<Club>();
}
public Club Club
{
get => _club;
set
{
_club = value;
OnPropertyChanged("Club");
}
}
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = "") => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
//Commands
private void AddClub()
{
}
Set breakpoints in property`s Club set section and try different modes, but it never stops.

All that I need to change is ta add Club = new Club(); in constructor of my ViewModel class.

Binding a list of object to grid

Trying to render a ListView with a grid into it. The grid contains two columns. The first one, with a button. The second one, with a Label.
Model contains two attributes. First one, a List of specific object. Second one, a string.
Finally, the label of the grid inside of listview will be binded to the one random attribute of list of object of the Model.
My best approach is:
<ListView x:Name="intervectionList"
ItemsSource="{Binding .}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid Padding="5">
<Grid.RowDefinitions>
<RowDefinition Height="20"></RowDefinition>
<RowDefinition Height="1"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"></ColumnDefinition>
<ColumnDefinition Width="3*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Button Text="Play" Grid.Row="0" Grid.Column="0" Clicked="OnLogginClicked"/>
<Label Grid.Row="0" Grid.Column="1" Text="{Binding random_attribute}"/>
<BoxView Color="Navy" HeightRequest="1" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2"/>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
CODE-BEHIND:
public Intervection()
{
InitializeComponent();
var obj= new Model();
this.BindingContext = prueba.List_of_object;
}
public class ViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void RaiseOnPropertyChange([CallerMemberName] string propertyName = null)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public ViewModel()
{
_viewmodel = new ViewModel();
}
private ViewModel _viewmodel;
private string _attribute1;
public string Attribute1
{
get { return _attribute1; }
set { _attribute1= value; RaiseOnPropertyChange(); }
}
.............
}
public class Model
{
public List<obj> Intervencion;
public string attribute2;
// Helpers...
}
That is not rendering anything.
I tried successive approaches. Coming from Basic ListView with string, ListView of object,... and so on. The problem is coming from when I insert the grid.
After check Stackoverflow. I found this link Create Grid from Code-Behind, but this is not serving to my purpose because I can´t re-write the view model. (I, even, tried to coded it).
As usual, thanks mates.

I have added the VerticalOptions to the Listview and Grid.
I have created a viewmodel in which I have one property, the list of items.
The viewmodel also implements INotifyPropertyChanged.
You can read about INotifyPropertyChanged here.
The INotifyPropertyChanged interface is used to notify clients,
typically binding clients, that a property value has changed.
XAML :
<ListView ItemsSource="{Binding MyObservableCollection}" VerticalOptions="FillAndExpand">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid Padding="5" VerticalOptions="Fill">
<Grid.RowDefinitions>
<RowDefinition Height="20"></RowDefinition>
<RowDefinition Height="1"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"></ColumnDefinition>
<ColumnDefinition Width="3*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Button Text="Play" Grid.Row="0" Grid.Column="0"/>
<Label Grid.Row="0" Grid.Column="1" Text="{Binding .}"/>
<BoxView Color="Navy" HeightRequest="1" Grid.Row="1"
Grid.Column="0" Grid.ColumnSpan="2"/>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
ViewModel :
public class ListViewWithGridViewModel : INotifyPropertyChanged
{
private ObservableCollection<string> _myObservableCollection;
public ListViewWithGridViewModel()
{
MyObservableCollection = new ObservableCollection<string>(new List<string> { "abc", "xyz", "pqr", "aaa", "abc", "xyz", "pqr", "aaa", "abc", "xyz", "pqr", "aaa" });
}
public ObservableCollection<string> MyObservableCollection
{
get { return _myObservableCollection; }
set
{
_myObservableCollection = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
XAML.cs :
public partial class ListViewWithGrid : ContentPage
{
public ListViewWithGrid()
{
InitializeComponent();
BindingContext = new ListViewWithGridViewModel();
}
}

Finally I got it. The xaml needed for it is the next one (you can complet all code coming from the code´s question). Posted just in case you all want to use another approach. Proper answer (more elegant) is #Rohit´s answer.
<ContentPage.Resources>
<ResourceDictionary>
<Color x:FactoryMethod="FromHex" x:Key="fondoBlancoPalido">
<x:Arguments>
<x:String>#F2F2F2</x:String>
</x:Arguments>
</Color>
</ResourceDictionary>
</ContentPage.Resources>
<ListView x:Name="listView" ItemsSource="{Binding .}" BackgroundColor="{StaticResource fondoBlancoPalido}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<Grid Padding="5">
<Grid.RowDefinitions>
<RowDefinition Height="60"></RowDefinition>
<RowDefinition Height="60"></RowDefinition>
<RowDefinition Height="10"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"></ColumnDefinition>
<ColumnDefinition Width="2*"></ColumnDefinition>
<ColumnDefinition Width="3*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Button Grid.Row="0" Grid.Column="0" Clicked="OnStartClicked" Image="play.png" BackgroundColor="Transparent" HorizontalOptions="Center" Grid.RowSpan="2"/>
<Label Grid.Row="0" Grid.Column="1" Text="Hora de Inicio: " XAlign="Center" YAlign="Center" TextColor="Black" FontAttributes="Bold"/>
<Label Grid.Row="0" Grid.Column="2" Text="{ Binding attribute3 }" XAlign="Center" YAlign="Center" TextColor="Black"/>
<Label Grid.Row="1" Grid.Column="1" Text="Encargado de la Tarea: " XAlign="Center" YAlign="Center" TextColor="Black" FontAttributes="Bold"/>
<Label Grid.Row="1" Grid.Column="2" Text="{ Binding attribute4 }" XAlign="Center" YAlign="Center" TextColor="Black"/>
<BoxView Color="Navy" HeightRequest="2" Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="3"/>
</Grid>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

UI not updating when a property changes

I have the Contact class that implements the INotifyPropertyChanged:
public class Contact : INotifyPropertyChanged
{
public Contact(Contact contact)
{
this.Username = contact.Username;
this.GUID = contact.GUID;
this.Msg = contact.Msg;
this.Ring = contact.Ring;
}
private string username;
public string Username
{
get { return username; }
set
{
username = value;
NotifyPropertyChanged(nameof(Username));
}
}
public Guid GUID { get; set; }
public bool Msg { get; set; }
private bool ring;
public bool Ring
{
get { return ring; }
set
{
ring = value;
NotifyPropertyChanged(nameof(Ring));
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
This is the main page:
public sealed partial class MainPage : Page
{
public ObservableCollection<Contact> Contacts = new ObservableCollection<Contact>();
public MainPage()
{
this.InitializeComponent();
Contacts.Add(new Contact("Contact001", Guid.NewGuid(), false, false));
Contacts.Add(new Contact("Contact002", Guid.NewGuid(), false, false));
}
private void AddContactButton_Click(object sender, RoutedEventArgs e)
{
Contacts.Add(new Contact("ContactN", Guid.NewGuid(), false, false));
}
private void ContactsListView_ItemClick(object sender, ItemClickEventArgs e)
{
Contact clickedContact = (Contact)e.ClickedItem;
int index = Contacts.IndexOf(clickedContact);
Contacts.ElementAt(index).Username = "Qwerty";
}
}
}
This is the XAML:
<Page
x:Class="ContactsListBinding.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:ContactsListBinding"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:data="using:ContactsListBinding.Models"
xmlns:namespace="ContactsListBinding.Models">
<Page.Resources>
<data:MessageToImageConverter x:Key="MessageToImageConverter" />
<data:RingToImageConverter x:Key="RingToImageConverter" />
</Page.Resources>
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<StackPanel Grid.Row="0" Grid.Column="0">
<Button Name="AddContactButton" Content="Add Contact" Click="AddContactButton_Click" />
<CheckBox Name="MessageMeCheckBox" Content="Message me" />
<CheckBox Name="DeleteMeCheckBox" Content="Delete me" />
</StackPanel>
<ListView Grid.Row="1" Grid.Column="0" Name="ContactsListView"
IsItemClickEnabled="True"
ItemClick="ContactsListView_ItemClick"
ItemsSource="{x:Bind Contacts}">
<ListView.ItemTemplate>
<DataTemplate x:DataType="data:Contact">
<Grid Width="500">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<TextBlock Grid.Row="0" Grid.Column="0" Text="{x:Bind Username}" VerticalAlignment="Center" />
<Image Grid.Row="0" Grid.Column="1" Width="15" Height="15" Source="{x:Bind Msg, Converter={StaticResource MessageToImageConverter}}" />
<Image Grid.Row="0" Grid.Column="2" Width="15" Height="15" Source="{x:Bind Ring, Converter={StaticResource RingToImageConverter}}" />
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</Page>
So, when I click on an item, I change it's Ring property to true. I have debugged and it is changing to true. The only problem is that my UI isn't updating. Any ideas why?

Okay guys, I finally got it to work. It seems that the Binding Mode should be set to OneWay, instead of the default OneTime. For example the correct xaml should be:
<TextBlock Grid.Row="0" Grid.Column="0" Text="{x:Bind Username, Mode=OneWay}" VerticalAlignment="Center" />
Thank you very much for all your help! :)