data is not getting in viewmodel on Icommand button click - mvvm

Question

I have a form for capturing data from user.
<StackLayout Spacing="10" Margin="20,10,20,0">
<Label Text="Job Name"></Label>
<Entry BackgroundColor="White" x:Name="JobName" Text="{Binding SelectedJob.Name,Mode=TwoWay}"/>
<Label Text="Goal"></Label>
<Entry BackgroundColor="White" x:Name="Goal" Text="{Binding SelectedJob.Goal,Mode=TwoWay}"/>
<Grid ColumnSpacing="8" HorizontalOptions="FillAndExpand">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Button Text="Save" Command="{Binding SubmitCommand}" BackgroundColor="#078fc1" Grid.Column="0" HorizontalOptions="FillAndExpand"/>
<Button Text="Reset" BackgroundColor="#078fc1" Grid.Column="1" HorizontalOptions="FillAndExpand"/>
</Grid>
</StackLayout>
on button click i want to bind data to SelectedJob object.
this is my ViewModel
public class JobViewModel: INotifyPropertyChanged
{
public JobViewModel()
{
SubmitCommand = new Command(OnSubmitAsync);
}
private JobDTO selectedob { get; set; }
public JobDTO SelectedJob
{
get { return selectedob; }
set
{
selectedob = value;
OnPropertyChanged(nameof(SelectedJob));
}
}
public ICommand SubmitCommand { protected set; get; }
public async void OnSubmitAsync()
{
await.jobservice.postjob()
}
}
and this is my model
public class JobDTO:INotifyPropertyChanged
{
private string name { get; set; }
public string Name
{ get { return name;}
set
{
name = value;
OnPropertyChanged(nameof(Name));
}
}
private string goal;
public string Goal
{
get { return goal; }
set
{
goal = value;
OnPropertyChanged(nameof(Goal));
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
on button click i am getting SelectedJob as null,eventhough i made my class as JobDTO:INotifyPropertyChanged.can any one help me what i am doing here wrong.

Answer 1

I changed the code of ViewModel and model.
There is GIF of demo based on your code.
ViewModel of JobViewModel
If you want to used get/set method, one attribute corresponds to one get/set method, I also add OnPropertyChangedmethod.
public class JobViewModel : INotifyPropertyChanged
{
public JobViewModel()
{
SubmitCommand = new Command(OnSubmitAsync);
}
private JobDTO selectedob=new JobDTO();
public JobDTO SelectedJob
{
get { return selectedob; }
set
{
selectedob = value;
OnPropertyChanged("SelectedJob");
}
}
public ICommand SubmitCommand { protected set; get; }
public event PropertyChangedEventHandler PropertyChanged;
public async void OnSubmitAsync()
{
// i donnot know what is your aim of this part, i just pop up a alert that contains Name and Goal from Entry.
await Application.Current.MainPage.DisplayAlert("Alert", "Name: "+SelectedJob.Name+"\n"+ "Goal: "+ SelectedJob.Goal , "Ok");
}
protected virtual void OnPropertyChanged(string propertyName)
{
var changed = PropertyChanged;
if (changed != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
Model of JobDTO, The changed place is same with ViewModel
public class JobDTO: INotifyPropertyChanged
{
private string name;
public string Name
{
get { return name; }
set
{
name = value;
OnPropertyChanged("Name");
}
}
private string goal;
public string Goal
{
get { return goal; }
set
{
goal = value;
OnPropertyChanged("Goal");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
var changed = PropertyChanged;
if (changed != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
MainPage.xaml
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:DateBoundingDemo"
x:Class="DateBoundingDemo.MainPage">
<StackLayout Spacing="10" Margin="20,10,20,0">
<Label Text="Job Name"></Label>
<Entry BackgroundColor="White" x:Name="JobName" Text="{Binding SelectedJob.Name,Mode=TwoWay}"/>
<Label Text="Goal"></Label>
<Entry BackgroundColor="White" x:Name="Goal" Text="{Binding SelectedJob.Goal,Mode=TwoWay}"/>
<Grid ColumnSpacing="8" HorizontalOptions="FillAndExpand">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Button Text="Save" Command="{Binding SubmitCommand}" BackgroundColor="#078fc1" Grid.Column="0" HorizontalOptions="FillAndExpand"/>
<Button Text="Reset" BackgroundColor="#078fc1" Grid.Column="1" HorizontalOptions="FillAndExpand"/>
</Grid>
</StackLayout>
</ContentPage>
MainPage.xaml.cs
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
BindingContext =new JobViewModel();
}
}