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Xamarin forms : How to get a value of Entry Text from another content page

I am learning xamaring forms,
I would like to get an Entry text from another xaml.cs file
Here my Entry in my first xaml file (content page) :
<Entry x:Name="UserName" Text="" Placeholder="enter your name" />
And in my second content page I would like to get the value : UserName.Text
I would like to use BindableProprety because I am using this Popup plugin, if there is another solution I ll take
Thanks in advance

You can solve it creating a PopupPage because you're using Rg.Plugins.Popup, place an Entry and send an event when user press a button.
I have created an small demo.
1. The ask user name popup page.
XAML
<?xml version="1.0" encoding="utf-8" ?>
<pages:PopupPage
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:pages="clr-namespace:Rg.Plugins.Popup.Pages;assembly=Rg.Plugins.Popup"
x:Class="xamstack.AskUserPopupPage"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://xamarin.com/schemas/2014/forms/design"
mc:Ignorable="d">
<StackLayout BackgroundColor="White" Padding="20"
VerticalOptions="Center" HorizontalOptions="Fill">
<Entry x:Name="UserEntry"/>
<Button Text="Submit" Clicked="ButtonSubmitUser_OnClicked"/>
</StackLayout>
</pages:PopupPage>
Code behind
public partial class AskUserPopupPage : PopupPage
{
public AskUserPopupPage()
{
InitializeComponent();
}
private void ButtonSubmitUser_OnClicked(object sender, EventArgs e)
{
OnUserSubmitted(UserEntry.Text);
}
public event EventHandler<string> UserSubmitted;
protected virtual void OnUserSubmitted(string e)
{
UserSubmitted?.Invoke(this, e);
}
}
2. Finally the ViewModel and the Page to display/ask the user name.
ViewModel:
public class UserPageViewModel : INotifyPropertyChanged
{
private string _userName;
public string UserName
{
get => _userName;
set
{
if (_userName != value)
{
_userName = value;
OnPropertyChanged(nameof(UserName));
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Page XAML:
...
<ContentPage.BindingContext>
<UserPageViewModel/>
</ContentPage.BindingContext>
<StackLayout>
<Label Text="{Binding UserName,Mode=OneWay}"/>
<Button Text="Ask user" Clicked="ButtonAskUser_OnClicked"/>
</StackLayout>
...
Page code behind:
public partial class UserPage : ContentPage
{
public UserPage()
{
InitializeComponent();
}
private async void ButtonAskUser_OnClicked(object sender, EventArgs e)
{
var page = new AskUserPopupPage();
page.UserSubmitted += async (_, userName) =>
{
var vm = (UserPageViewModel) BindingContext;
vm.UserName = userName;
await Navigation.PopPopupAsync();
};
await Navigation.PushPopupAsync(page);
}
}

Dynamically add UserControls to a Custom Xamarin ListView using a bindable property

I have already created all of the controls, and have tested that the controls are added as needed without using the binding.
The issue is as soon as I add the binding which is supposed to determine which control to add, the controls stop working as needed.
The list view control will be populated from a collection of a class, which will have an indicator field to determine which control needs to be loaded. The list view contains a 2nd user control which basically acts as a placeholder for the correct control, it has a bindable property of type text which is set to determine the correct control to be loaded.
Here is the XAML Code for the list view control
<ContentView.Content>
<StackLayout>
<Label Text="Binding Control Type"/>
<Entry x:Name="cntName"/>
<ListView x:Name="GroupedView" GroupDisplayBinding="{Binding Title}" HasUnevenRows="True" GroupShortNameBinding="{Binding ShortName}" IsGroupingEnabled="True">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.ContextActions>
<MenuItem Text="Add Comment"/>
<MenuItem Text="Add Attachment"/>
</ViewCell.ContextActions>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="3*"/>
<ColumnDefinition Width="7*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="3*"/>
<RowDefinition Height="7*"/>
</Grid.RowDefinitions>
<Label Text="{Binding QUESTION_ID}" Grid.Row="0" Grid.Column="0" VerticalTextAlignment="Center" FontSize="Medium"/>
<Label Text="{Binding QUESTION_DETAILS}" Grid.Row="1" Grid.Column="0" VerticalTextAlignment="Center" FontSize="Medium"/>
<con:ucListViewControls ControlType="{Binding QUESTION_ANSWERCONTROL}" Grid.Row="1" Grid.Column="1"/>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.ContextActions>
<MenuItem Text="Add Comment"/>
<MenuItem Text="Add Attachment"/>
</ViewCell.ContextActions>
<StackLayout Orientation="Horizontal" Padding="5,5,5,5" BackgroundColor="#E2F5F9">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding Source={x:Reference this}, Path=Tapped}" CommandParameter="{Binding .}"/>
</StackLayout.GestureRecognizers>
<Button Image="{Binding StateIcon}" BackgroundColor="Transparent" BorderColor="Transparent" BorderWidth="0"/>
<Label Text="{Binding Title}" TextColor="#005569" FontSize="15" VerticalOptions="Center"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
</ListView>
</StackLayout>
</ContentView.Content>
And the code behind for the control
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ucExpandibleListView : ContentView
{
private ObservableCollection<dbQuestionGroup> _allGroups;
private ObservableCollection<dbQuestionGroup> _expandedGroups;
public ucExpandibleListView()
{
InitializeComponent();
Tapped = new Command(x => HeaderTapped(x));
_allGroups = new ObservableCollection<dbQuestionGroup>()
{
new dbQuestionGroup("Category 1", "C1", false)
{
new dbQuestionModel() { QUESTION_ID = 1, QUESTION_DETAILS = "Testing Question 1", QUESTION_ANSWERCONTROL = "RBL" },
new dbQuestionModel() { QUESTION_ID = 2, QUESTION_DETAILS = "Testing Question 2", QUESTION_ANSWERCONTROL = "" }
}
};
UpdateListContent();
}
private void UpdateListContent()
{
_expandedGroups = new ObservableCollection<dbQuestionGroup>();
foreach (dbQuestionGroup group in _allGroups)
{
dbQuestionGroup newGroup = new dbQuestionGroup(group.Title, group.ShortName, group.Expanded);
newGroup.QuestionCount = group.Count;
if (group.Expanded)
{
foreach (dbQuestionModel question in group)
{
newGroup.Add(question);
}
}
_expandedGroups.Add(newGroup);
}
GroupedView.ItemsSource = _expandedGroups;
}
public Command Tapped { get; set; }
private void HeaderTapped(object group)
{
var groupCat = (dbQuestionGroup)group;
int selectedIndex = _expandedGroups.IndexOf(groupCat);
if (groupCat.Expanded)
{
_allGroups[selectedIndex].Expanded = false;
}
else
{
_allGroups.ToList().ForEach(x => x.Expanded = false);
_allGroups[selectedIndex].Expanded = !_allGroups[selectedIndex].Expanded;
}
UpdateListContent();
}
}
Here is the XAML Code for the placeholder control
<ContentView.Content>
<StackLayout x:Name="stkPlaceholder">
</StackLayout>
</ContentView.Content>
And the code behind for the placeholder control
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ucListViewControls : ContentView, INotifyPropertyChanged
{
public ucListViewControls()
{
InitializeComponent();
}
#region Control Attributes
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(string info)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(info));
}
#endregion
#region Bindable Properties
public static readonly BindableProperty ControlTypeProperty = BindableProperty.Create(nameof(ControlType), typeof(string), typeof(ucListViewControls));
public string ControlType
{
get
{
return (string)GetValue(ControlTypeProperty);
}
set
{
SetValue(ControlTypeProperty, value);
AddControl();
NotifyPropertyChanged("ControlType");
}
}
#endregion
public void AddControl()
{
switch (ControlType)
{
case "RBL":
ucRadiobuttons radiobuttons = new ucRadiobuttons();
radiobuttons.lblTitle1 = "Yes";
radiobuttons.lblTitle2 = "No";
radiobuttons.lblTitle3 = "N/A";
radiobuttons.OnColor1 = Color.Green;
radiobuttons.OnColor2 = Color.Red;
radiobuttons.OnColor3 = Color.Transparent;
stkPlaceholder.Children.Add(radiobuttons);
break;
default:
Entry placeholder = new Entry();
stkPlaceholder.Children.Add(placeholder);
break;
}
}
}
I have tested that the controls are added without the binding, which works perfectly.
I have tried to rewrite the bindable property multiple times in case I missed something, I also could not find any post relating to something similar which wouldve helped me.
Any clues?
The first screenshot shows the expected output, and the seconds screenshots shows what happens when the binding is applied.
dbQuestionModel:
using System.Collections.Generic;
namespace PivotMobile_BusinessLayer.Models
{
public class dbQuestionModel
{
public int QUESTION_PK { get; set; }
public int QUESTION_ID { get; set; }
public string QUESTION_CATEGORY { get; set; }
public string QUESTION_DETAILS { get; set; }
public string QUESTION_TYPE { get; set; }
public string QUESTION_ANSWERCONTROL { get; set; }
public string QUESTION_COMMENT { get; set; }
public List<string> QUESTION_ATTACHMENTS { get; set; }
}
}
dbQuestionGroup:
using System.Collections.ObjectModel;
using System.ComponentModel;
namespace PivotMobile_BusinessLayer.Models
{
public class dbQuestionGroup : ObservableCollection<dbQuestionModel>, INotifyPropertyChanged
{
public static ObservableCollection<dbQuestionGroup> All { private set; get; }
private bool _expanded;
public string Title { get; set; }
public string ShortName { get; set; }
public bool Expanded
{
get
{
return _expanded;
}
set
{
if (_expanded != value)
{
_expanded = value;
OnPropertyChanged("Expanded");
OnPropertyChanged("StateIcon");
}
}
}
public string StateIcon
{
get
{
return Expanded ? "expanded_blue.png" : "collapsed_blue.png";
}
}
public int QuestionCount { get; set; }
public dbQuestionGroup(string title, string shortName, bool expanded = true)
{
Title = title;
ShortName = shortName;
Expanded = expanded;
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
ListView Page XAML:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="PivotMobile.Views.ObservationsView"
xmlns:con="clr-namespace:PivotMobile.Controls">
<ContentPage.Content>
<StackLayout Margin="5">
<con:ucExpandibleListView/>
</StackLayout>
</ContentPage.Content>
</ContentPage>
ListView Page Code Behind:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace PivotMobile.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ObservationsView : ContentPage
{
public ObservationsView ()
{
InitializeComponent ();
}
}
}

Databinding is not working between two tabbedpage children

I'm new to Xamarin.Forms development and I'm trying to build a tiny Xamarin app to start.
My app currently has one main TabbedPage that has two ContentPages children. On the ListePage, I have a ListView with an ObservableCollection with OlonaModel is an object with an int Numero and a Text string. I would like the Details page to show details of the selected OlonaModel from the listview of ListePage, but the Details page doesn't seem to update to changes when I select an item from the listview.
Both of the content pages are bound to the same ListPageViewModel. The view model updates when I select an item from the listview, but the changes aren't reflected on the Details page and I'm really confused.
How can I make the Details refresh itself when the SelectedItem of the view model gets set ?
The MainPage :
<?xml version="1.0" encoding="utf-8" ?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:App.Views"
xmlns:viewmodels="clr-namespace:App.ViewModels"
mc:Ignorable="d"
x:Class="App.MainPage">
<TabbedPage.Children>
<local:ListePage/>
<local:Details/>
</TabbedPage.Children>
</TabbedPage>
The ListePage.xaml (ContentPage1 in the post) :
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Class="App.Views.ListePage"
Title="Liste">
<ContentPage.Content>
<StackLayout>
<ListView x:Name="ListeMipoitra" ItemSelected="ListeMipoitra_ItemSelected">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Label Text="{Binding Numero}" Grid.Column="0" FontSize="Medium" FontAttributes="Bold"/>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ContentPage.Content>
</ContentPage>
The ListePage.xaml.cs :
namespace App.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ListePage : ContentPage
{
public static ListePageViewModel viewModel;
public ListePage()
{
InitializeComponent();
viewModel = new ListePageViewModel();
this.BindingContext = viewModel;
ListeMipoitra.ItemsSource = viewModel.listeOlonaVM;
}
private void ListeMipoitra_ItemSelected(object sender, SelectedItemChangedEventArgs e)
{
viewModel.setSelected((OlonaModel)e.SelectedItem);
}
}
}
The Details.xaml (ContentPage2 in the post) :
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Class="App.Views.Details"
Title="Détails">
<ContentPage.Content>
<StackLayout>
<Label Text="{Binding Text}"/>
</StackLayout>
</ContentPage.Content>
</ContentPage>
The Details.xaml.cs :
namespace App.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class Details : ContentPage
{
public Details()
{
InitializeComponent();
this.BindingContext = ListePage.viewModel.selected;
}
}
}
The ListePageViewModel.cs :
Note: I'm using Fody and PropertyChanged.Fody weaver, so the RaisePropertyChanged() event (should be) is called automatically when a property changes
namespace App.ViewModels
{
public class ListePageViewModel : INotifyPropertyChanged
{
public ObservableCollection<OlonaModel> listeOlonaVM;
public OlonaModel selected { get; set; }
public ListePageViewModel()
{
listeOlonaVM = new ObservableCollection<OlonaModel>();
listeOlonaVM = ListeOlona.liste;
}
public event PropertyChangedEventHandler PropertyChanged;
public void setSelected(OlonaModel olona)
{
selected = olona;
}
}
}
The model of the Olona object :
namespace App.Models
{
public class OlonaModel
{
public int Numero { get; set; }
public string Text { get; set; }
public OlonaModel(int num, string text)
{
this.Numero = num;
this.Text= text;
}
}
}
The ListeOlona.cs where the model of the list is stored:
The InitializeList() method is called at App Startup.
namespace App.ViewModels
{
public static class ListeOlona
{
public static ObservableCollection<OlonaModel> liste = new ObservableCollection<OlonaModel>();
public static void InitializeList()
{
liste.Add(new OlonaModel(1,
"FirstItem"));
liste.Add(new OlonaModel(2,
"Second Item"));
}
}
}

According to your description, there is tabbedpage, two pages, one is Listpage, another is detailpage, you want to select listview item in listpage, then other detail info will display detailpage, am I right?
If yes, I suggest you can do this like this:
TabbedPage:
<TabbedPage
x:Class="App4.TabbedPage2"
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:App4"
x:Name="tabbedpage2">
<!-- Pages can be added as references or inline -->
<TabbedPage.Children>
<local:ListPage Title="Mian page" BindingContext="{Binding}" />
<local:DetailPage Title="Detail page" BindingContext="{Binding select}" />
</TabbedPage.Children>
public partial class TabbedPage2 : TabbedPage
{
public TabbedPage2 ()
{
InitializeComponent();
this.BindingContext = new ListePageViewModel();
}
}
public class OlonaModel
{
public int Numero { get; set; }
public string Text { get; set; }
}
public class ListePageViewModel : ViewModelBase
{
public ObservableCollection<OlonaModel> listeOlonaVM { get; set; }
private OlonaModel _select;
public OlonaModel select
{
get { return _select; }
set
{
_select = value;
RaisePropertyChanged("select");
}
}
public ListePageViewModel()
{
listeOlonaVM = new ObservableCollection<OlonaModel>()
{
new OlonaModel(){Numero=1,Text="first item"},
new OlonaModel(){Numero=2,Text="second item"},
new OlonaModel(){Numero=3,Text="third item"},
new OlonaModel(){Numero=4,Text="fouth item"}
};
select = listeOlonaVM[0];
}
}
ListPage:
<StackLayout>
<ListView ItemsSource="{Binding listeOlonaVM}" SelectedItem="{Binding select}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="{Binding Numero}" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
DetailPage:
<StackLayout>
<Label
HorizontalOptions="CenterAndExpand"
Text="{Binding Text}"
VerticalOptions="CenterAndExpand" />
</StackLayout>
ViewModelBase implement INotifyPropertyChanged interface.
public class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void RaisePropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}

Xamarin Forms two way binding ActivityIndicator

I am new to Xamarin and I am using ActivityIndicator to say users that app is downloading the data. Problem is that I am using MVVM pattern and I need to set the values IsRunning and IsVisible from ViewModel. I have simple view:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:HmtMobile"
x:Class="HmtMobile.MainPage"
Title="Přihlášení"
>
<ScrollView>
<StackLayout Margin="10" Spacing="15" VerticalOptions="Center">
<ActivityIndicator x:Name="ActivityIndicator" Color="Green" IsRunning="{Binding IsBusy, Mode=TwoWay}" IsVisible="{Binding IsBusy, Mode=TwoWay}"/>
<Entry Placeholder="Uživatelské jméno" Text="{Binding UserName}"></Entry>
<Entry Placeholder="Heslo" Text="{Binding Password}" IsPassword="True"></Entry>
<Button Text="Přihlášení" Command="{Binding LoginCommand}" BackgroundColor="#77D065" TextColor="White"></Button>
</StackLayout>
</ScrollView>
In the view constructor I am assigning the BindingContext
public MainPage()
{
InitializeComponent();
this.BindingContext = new CredentialViewModel(this);
}
Other properties works because when I want to login the properties returns the actual username and password but the twoway binding doesn´t. Properties are declared same so I do not understand why is this happening.
private string password;
public string Password
{
get { return password; }
set { password = value; OnPropertyChanged(); }
}
private bool isBusy;
public bool IsBusy
{
get { return isBusy; }
set { isBusy = value; OnPropertyChanged(); }
}
I am using the simple Login method.
private async Task Login()
{
IsBusy = true;
await Task.Delay(5000);
}
THe ActivityIndicator is not appearing. Does anyone know why? OnPropertyCHanged is coded this way:
public class Bindable
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}

I figure it out based on Felix message. The problem was that in Bindable class I forgot to add : INotifyPropertyChanged.

What's wrong with my Xamarin.Forms project?

I'm trying to make a Xamarin.Forms project where I have a BoxView and an Entry field and a Button. I want to enter the name of a color into my Entry field, press the button, and have my BoxView change to the color that I input. Here is the code I have written till now:
Views/MainView.xaml
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="TestGround.MainView">
<ContentPage.Content>
<StackLayout VerticalOptions="Center">
<Label
Text="Enter a color:"
VerticalOptions="Center"
HorizontalOptions="Center"
/>
<BoxView
Color="{Binding Color}"
/>
<Entry
Text="{Binding Name}"
/>
<Button
Text="Enter"
Command="{Binding SetColorCommand}"
/>
</StackLayout>
</ContentPage.Content>
</ContentPage>
ViewModels/MainViewModel.cs
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Threading.Tasks;
using System.Windows.Input;
using Xamarin.Forms;
namespace TestGround
{
public class MainViewModel :INotifyPropertyChanged
{
private string _color; //backing field for Greeting
public string Color //implementation for Greeting method
{
get { return _color; }
set
{
_color = value;
OnPropertyChanged ("Color"); //Notify view that change has taken place
}
}
public string Name { get; set; } //Name method for Entry field
public ICommand SetColorCommand { get; set; } //ICommand binds to buttons in XAML
public void SetColor() //Need a regular method to add to ICommand
{
Color = Name;
}
//Main VIEW MODEL
public MainViewModel ()
{
//Color = Name;
Name = "Enter color here";
SetColorCommand = new Command(SetColor); //Regular command added to ICommand
}
#region PropertyChangedRegion
public void OnPropertyChanged (string propertyName)
{
if (PropertyChanged != null)
PropertyChanged (this, new PropertyChangedEventArgs (propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
#endregion
}
}
Here is the error I get:
Java.Lang.RuntimeException: java.lang.reflect.InvocationTargetException
I want to know if my approach is wrong and how can I go about fixing it and making this pretty simple program.

According to the BoxView Documentation, the property "Color" must actually be a color... where as you have it defined as a string named color. Your types are mixed up. It should be something like Colors.Blue.

You can use class ColorTypeConverter for change string to Color.
I 've simplified your problem to this source code
//You simplified model
public class bModel : BindableObject
{
private Color _realColor;
public Color Color
{
get { return _realColor; }
set
{
_realColor = value;
OnPropertyChanged ("Color");
}
}
public string _stringColor;
public string StringColor {
get {
return _stringColor;
}
set {
_stringColor = value;
Color = (Color)(new ColorTypeConverter ()).ConvertFrom (_stringColor);
}
}
public bModel ()
{
StringColor = "Blue";
}
}
}
//Your simplified page xaml
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="s2c.MyPage">
<ContentPage.Content>
<BoxView x:Name="box" Color="{Binding Color}"/>
</ContentPage.Content>
</ContentPage>
//Your simplified page csharp
public partial class MyPage : ContentPage
{
public MyPage ()
{
InitializeComponent ();
this.BindingContext = new bModel ();
}
}