MVVM and Interfaces

Question

Hello
I am trying to wrap my head around MVVM and Interfaces. It doesn't all make sense to me yet. In the app below I have 3 xaml ENTRY controls and the data from that control I want to pass to a list. I would very much appreciate if someone could give me some idea on how to code this problem correctly.

thank you in advance.

[StartPage.xaml]
<ContentPage.Content>
<StackLayout Margin="20">
<Entry Placeholder="First Name"></Entry>
<Entry Placeholder="Last Name" Text="{Binding LastName}"></Entry>
<Entry Placeholder="EmailAddress"></Entry>
<Button Text="Save"
Command="{Binding saveCommand}"></Button>
</StackLayout>
</ContentPage.Content>

[StartPage.xaml.cs]

using Interfaces.Model;  
using Interfaces.ViewModel;  
using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Text;  
using System.Threading.Tasks;  
using Xamarin.Forms;  
using Xamarin.Forms.Xaml;  
  
namespace Interfaces.View  
{  
    [XamlCompilation(XamlCompilationOptions.Compile)]  
    public partial class StartPage : ContentPage  
    {  
        public StartPage()  
        {  
            InitializeComponent();  
            BindingContext = new StartPageViewModel();              
        }  
    }  
}  

[IPeople.cs]

namespace Interfaces.Model  
{  
    public interface IPeople  
    {  
        string EmailAddress { get; set; }  
        string FirstName { get; set; }  
        string LastName { get; set; }  
    }  
}  

[People.cs]

using System;  
using System.Collections.Generic;  
using System.Text;  
  
namespace Interfaces.Model  
{  
  
        public class People : IPeople  
        {  
            private string _firstName;  
            public string FirstName  
            {  
                get { return _firstName; }  
                set { _firstName = value; }  
            }  
            private string _lastName;  
            public string LastName  
            {  
                get { return _lastName; }  
                set { _lastName = value; }  
            }  
      
            private string _emailAddress;  
            public string EmailAddress  
            {  
                get { return _emailAddress; }  
                set { _emailAddress = value; }  
            }  
        }  
    }  

[StartPageViewModel.cs]

using Interfaces.Model;  
using System;  
using System.Collections.Generic;  
using System.Text;  
using System.Windows.Input;  
using Xamarin.Forms;  
  
namespace Interfaces.ViewModel  
{  
    public class StartPageViewModel   
    {  
          
        public ICommand saveCommand { get; set;}          
  
        public StartPageViewModel()  
        {  
            saveCommand = new Command(Save);  
        }  
  
        private void Save()  
        {  
            List<IPeople> person = People();              
        }  
  
        private static List<IPeople> People()  
        {  
            List<IPeople> output = new List<IPeople>();  
  
            // get data from xaml ENTRY control  
  
            return output;  
        }  
    }  
}  

Answer 1

Hi HeinzDeubler-1084,

Welcome to our Microsoft Q&A platform!

You only need to define the corresponding properties in the ViewModel.

StartPage.xaml

<StackLayout Margin="20">  
    <Entry Placeholder="First Name" Text="{Binding FirstName}"></Entry>  
    <Entry Placeholder="Last Name" Text="{Binding LastName}"></Entry>  
    <Entry Placeholder="EmailAddress" Text="{Binding EmailAddress}"></Entry>  
    <Button Text="Save"  
            Command="{Binding saveCommand}"></Button>  
</StackLayout>  

StartPageViewModel.cs

public class StartPageViewModel  
{  
    public string FirstName { get; set; }  
    public string LastName { get; set; }  
    public string EmailAddress { get; set; }  
  
    List<IPeople> person = new List<IPeople>();  
  
    public ICommand saveCommand { get; set; }  
  
    public StartPageViewModel()  
    {  
        saveCommand = new Command(Save);  
    }  
  
    private void Save()  
    {  
        person.Add(new People  
        {  
            FirstName = FirstName,  
            LastName = LastName,  
            EmailAddress = EmailAddress  
        });  
    }  
}  

Regards,
Kyle

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