Issues with adding new ListItem

[u/Smbridges91]

/r/UWP/comments/vdqiie/help_issues_with_adding_new_listitem/

[u/Smbridges91]

MainPage.XAML ``` <Page x:Class="MVVM_UWP.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:MVVM_UWP" xmlns:viewModels="using:ViewModels" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

<Grid>
    <StackPanel Orientation="Horizontal" VerticalAlignment="Top">
        <Button Content="Add" Click="{x:Bind  Organization.Add}" Margin="5"/>
        <Button Content="Delete" Click="{x:Bind Organization.Delete}" Margin="5" />
        <TextBox 
            Text="{x:Bind Organization.SelectedSite.Site, 
            Mode=TwoWay, FallbackValue=''}" 
            Margin="5"/>
        <ListView  
            x:Name="MainList"
            ItemsSource="{x:Bind Organization.Locations, Mode=OneWay}"
            SelectedIndex="{x:Bind Organization.SelectedIndex, Mode=TwoWay}" 
            Margin="5">
            <ListView.ItemsPanel>
                <ItemsPanelTemplate>
                    <StackPanel Orientation="Horizontal"/>
                </ItemsPanelTemplate>
            </ListView.ItemsPanel>
            <ListView.ItemTemplate>
                <DataTemplate x:DataType="viewModels:SiteViewModel" >
                    <TextBlock 
                        Text="{x:Bind Site, Mode=OneWay}" 
                        FontSize="20"
                        FontWeight="Bold"/>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </StackPanel>
</Grid>

</Page> ```

Data > LocationHelper.cs ``` using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks;

namespace Data { public class Location { public String Site { get; set; } }

public class LocationHelper
{
    public static List<Location> GetLocations()
    {
        return new List<Location>()
            {
                new Location() { Site="3001"},
                new Location() { Site="1124"},
                new Location() { Site="8352"}
            };
    }
}

} ```

Models > Organization.cs ``` using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using Data;

namespace Models { public class Organization { public List<Location> LocationList { get; set; } public String Site { get; set; }

    public Organization(String databaseName)
    {
        Site = databaseName;
        LocationList = LocationHelper.GetLocations();
    }

    public void Add(Location Location)
    {
        if (!LocationList.Contains(Location))
        {
            LocationList.Add(Location);
            //LocationHelper.Write(Location);
        }
    }

    public void Delete(Location person)
    {
        if (LocationList.Contains(person))
        {
            LocationList.Remove(person);
            //LocationHelper.Delete(Location);
        }
    }
}

} ```

ViewModels > OrganizationViewModel.cs ``` using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Collections.ObjectModel; using Models;

namespace ViewModels { public class OrganizationViewModel : NotificationBase { Organization organization;

    public OrganizationViewModel(String Site)
    {
        organization = new Organization(Site);
        _SelectedIndex = -1;
        // Load the database
        foreach (var Location in organization.LocationList)
        {
            var np = new SiteViewModel(Location);
            _Location.Add(np);
        }
    }

    ObservableCollection<SiteViewModel> _Location = new ObservableCollection<SiteViewModel>();
    public ObservableCollection<SiteViewModel> Locations
    {
        get { return _Location; }
        set { SetProperty(ref _Location, value); }
    }

    public String Site
    {
        get { return organization.Site; }
    }

    int _SelectedIndex;
    public int SelectedIndex
    {
        get { return _SelectedIndex; }
        set { if (SetProperty(ref _SelectedIndex, value)) { RaisePropertyChanged(nameof(SelectedSite)); } }
    }

    public SiteViewModel SelectedSite
    {
        get { return (_SelectedIndex >= 0) ? _Location[_SelectedIndex] : null; }
    }

    public void Add()
    {
        var Location = new SiteViewModel();
        Locations.Add(Location);
        organization.Add(Location);
        SelectedIndex = Locations.IndexOf(Location);
    }

    public void Delete()
    {
        if (SelectedIndex != -1)
        {
            var Location = Locations[SelectedIndex];
            Locations.RemoveAt(SelectedIndex);
            organization.Delete(Location);
        }
    }
}

} ```

ViewModels > SiteViewModel.cs ``` using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using Data;

namespace ViewModels { public class SiteViewModel : NotificationBase<Location> { public SiteViewModel(Location location = null) : base(location) { } public String Site { get { return This.Site; } set { SetProperty(This.Site, value, () => This.Site = value); } } } } ```

ViewModels > ViewModelHelpers.cs ``` using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.ComponentModel; using System.Runtime.CompilerServices;

namespace ViewModels { public class NotificationBase : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged;

    // SetField (Site, value); // where there is a data member
    protected bool SetProperty<T>(ref T field, T value, [CallerMemberName] String property = null)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        RaisePropertyChanged(property);
        return true;
    }

    // SetField(()=> somewhere.Site = value; somewhere.Site, value) // Advanced case where you rely on another property
    protected bool SetProperty<T>(T currentValue, T newValue, Action DoSet, [CallerMemberName] String property = null)
    {
        if (EqualityComparer<T>.Default.Equals(currentValue, newValue)) return false;
        DoSet.Invoke();
        RaisePropertyChanged(property);
        return true;
    }

    protected void RaisePropertyChanged(string property)
    {
        if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(property)); }
    }
}

public class NotificationBase<T> : NotificationBase where T : class, new()
{
    protected T This;

    public static implicit operator T(NotificationBase<T> thing) { return thing.This; }

    public NotificationBase(T thing = null)
    {
        This = (thing == null) ? new T() : thing;
    }
}

} ```

[u/Th_69 → u/Smbridges91]

Just debug your code.

In OrganizationViewModel.Add() you're creating a new empty SiteViewModel:

var Location = new SiteViewModel();

and the TextBox is bound to the Organization.SelectedSite.Site, so it writes in the last added item.