Saving with SQL - sql

Question

Hi all I have a page that I'm trying to ADD to a list and save it with viewmodel and SQL. but my list is empty Can you tell me where am I wrong??
on my Xaml (Page1):
<Entry Margin="5" Text="{Binding Xname}" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" FontSize="16" x:Name="entry1" Placeholder="Enter X-rays (6 MV)" PlaceholderColor="White" BackgroundColor="Gray"/>
<Button Grid.Column="0"
Grid.Row="2"
FontAttributes="Bold"
Command="{Binding AddXrayCommand}"
Text="Add" />
<ListView Grid.Row="3" Grid.ColumnSpan="2" HasUnevenRows="True" Margin="40"
ItemsSource="{Binding energyX}" SelectedItem="{Binding selecteditemX}"
HorizontalOptions="Start" WidthRequest="150" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="30"></RowDefinition>
<RowDefinition Height="5"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
</Grid.ColumnDefinitions>
<Label Grid.Row="0" BackgroundColor="White" Text="{Binding xray}" FontSize="Large" HorizontalTextAlignment="Center" TextColor="Black" WidthRequest="35"/>
<Frame Grid.Row="1" BackgroundColor="Gray"></Frame>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
my Model (Energypage):
public class EnergyX
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public string xray { get; set; }
}
And on my EnergyViewModel:
public class EnergyViewModel
{
public SQLiteConnection conn;
public ObservableCollection<EnergyX> energyX { get; set; } = new ObservableCollection<EnergyX>();
public string Xname { get; set; }
public ICommand AddXrayCommand => new Command(AddX);
public SQLiteConnection GetSQLiteConnection()
{
var fileName = "Energys.db";
var documentPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.LocalApplicationData);
var path = Path.Combine(documentPath, fileName);
var connection = new SQLiteConnection(path);
return connection;
}
public void AddX()
{
if (Xname != null && Xname.Length > 0)
{
EnergyX XX = new EnergyX();
XX.xray = Xname;
conn = GetSQLiteConnection();
conn.CreateTable<EnergyX>();
var dataX = conn.Table<EnergyX>();
var resultX = conn.Insert(XX);
energyX = new ObservableCollection<EnergyX>(conn.Table<EnergyX>().ToList());
}
}
}
}
I did bond my page1 to Energyviewmodel, and it works find when I didn't use SQL service, I think my SQL has problem...
I have debug the viewmodel and program run to the end of the Viewmodel but my xaml page list is empty.

Answer 1

this line creates a completely new instance of energyX when your ListView is bound to the old instance
energyX = new ObservableCollection(conn.Table().ToList());
there are two ways you could fix this
option 1, use INotifyPropertyChanged and raise a PropertyChanged event in the setter of energyX
option 2, don't create a new instance of energyX. Instead just add the new item to the existing instance
energyX.Add(XX);