Get values of textboxes in child-window to add row to BindableCollection-bound DataGrid

[olegul86]

Still loving the framework!
But I've ran into some issues. I re-made my simple application with Stylet, because I couldn't figure this out with my old framework. I'm sure there's just something obvious I'm missing.

I've a DataGrid bound to an BindableCollection, which works nicely:

But when I try to add a new row (using TextBoxes in a child-window), I'm causing a mess. It doesn't automatically update, and requires me to re-open the window.
This is my method to add to the database and refresh the BindableCollection:

using (SqlConnection sqlCon = new(ConnectionString.connectionString))
using (SqlCommand sqlCmd = new(sqlString, sqlCon)) {

    sqlCon.Open();

    AddLicenseHolderView view = Application.Current.Windows.OfType<AddLicenseHolderView>().FirstOrDefault();

    sqlCmd.Parameters.AddWithValue("@Foretaksnavn", view.txtForetaksnavn.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Foretaksnummer", view.txtForetaksnr.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Adresse", view.txtAdresse.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Postnummer", view.txtPostnummer.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Poststed", view.txtPoststed.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@BIC", view.txtBIC.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@IBAN", view.txtIBAN.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Kontakt", view.txtKontakt.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Epost", view.txtEpost.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Tlf", view.txtTlf.Text.ToString());
    sqlCmd.Parameters.AddWithValue("@Kontonummer", view.txtKontonr.Text.ToString());
    sqlCmd.ExecuteNonQuery();
}

this.RequestClose(true);

LicenseHolders.AddRange();
NotifyOfPropertyChange(() => LicenseHolders);
LicenseHolders.Refresh();

As you see, I instantiate the View, in order to get the TextBox values, which is not MVVM friendly, and also, doesn't work, for some reason.......

I've bound this method to a button in the child-window using your 's:Action'
I've also put the instance of the BindableCollection in the constructor:

LicenseHolders = new BindableCollection<LicenseHolder>();

The TextBoxes in the child-window is bound like so:

Text="{Binding Path=Foretaksnavn}"

Where "Foretaksnavn" is one of the strings I have in my LicenseHolder class.

I'm guessing this last part is where I wrong?

I'm thinking I need something like this:

    private string _name;
    public string Name
    {
        get { return _name; }
        set { SetValue(ref _name, value); }
    }

in the child-windows ViewModel, but I couldn't get that to work. How would I get the value of the TextBoxes in a ViewModel-first friendly approach?

Any tips to get my thinking straightened would be most welcome!

[canton7]

The TextBoxes in the child-window is bound like so:

"child-window" is the AddLicenseHolderView?

LicenseHolders.AddRange();

You're not passing anything to AddRange, so this is a syntax error. It's not clear what you're trying to do here.

Text="{Binding Path=Foretaksnavn}"

Presumably you have a property called Foretaksnavn on the AddLicenceHolderViewModel?

---

I'm afraid there are many parts to this, and you're only showing a little snippet, so it's hard for me to work out what you're even trying to describe.

[olegul86]

Re-reading my post, I want to apologize for how bad my explanation was! No wonder you couldn't fully understand it.
Yes - what I refer to as my child-window is AddLicenseHolderView - that is where the TextBoxes live whom I want to reference.
When I'm done adding text into the TextBoxes, and click Save, I want a new row to be added to my DataGrid (doesn't happen, although the Sql server is updated, so the new row is there when I re-open the window).
Foretaksnavn, and the rest of my getter/setters is in a model class, called LicenseHolder.cs.
As you can see, there are many holes to my knowledge, so I'm struggling to explain it.
I am also confused about whether or not BindableCollection takes care of the notification of property changes, or if I still need to implement the INotifyPropertyChanged interface (for the model class, the view models, or none at all...)

This is how my app looks like

This is where my DataGrid is at. Clicking "Ny løyvehaver" opens up the child-window "AddLicenseHolderView":

I've added test data. And then I click "Lagre" (save button). "AddLicenseHolderView" window is closed, and the DataGrid is not updated.
If I restart the parent-window ("LicenseHolderView"), the row shows.

I've hidden the other columns.

Not sure why I'm showing you this lol, but hopefully it could help make my intent a bit clearer.

[canton7]

Thanks, that's made the context clearer.

So, I think there are two parts to your question?

1. You're trying to access the values of those text boxes, without referencing the view directly
2. You're trying to update the DataGrid

The code you've shared doesn't cover either of these: you don't show the code in AddLicenseHolderView or the corresponding ViewModel where you bind those text inputs to their properties in the ViewModel, and you don't show code where you try to add the new item to the DataGrid.

Can you please post the full code of both the AddLicenseHolderView, AddLicenseHolderViewModel and the parent ViewModel which contains the data for the DataGrid.

BindableCollection implements INotifyCollectionChanged. This interface notifies consumers when items are added to or removed from the collection. It won't notify consumers if the property containing the BindableCollection is re-assigned (INotifyPropertyChanged on the property takes care of that), and it won't notify consumers if a property of one of the items inside the BindableCollection is changed (INotifyCollectionChanged on the item takes care of that).

public class Item : PropertyChangedBase
{
    private string _name;
    public string Name
    {
        get => _name;
        set => SetAndNotify(ref _name, value);
    }
}

public class Parent : PropertyChangedBase
{
    private BindableCollection<Item> _items;
    public BindableCollection<Item> Items
    {
        get => _items;
        set => SetAndNotify(ref _items, value);
    }

    public void Test()
    {
        // Parent.PropertyChanged is fired, for property "Items"
        Items = new BindableCollection<Item>();

        // BindableCollection<Item>.CollectionChanged is fired
        Items.Add(new Item());

        // Item.PropertyChanged is fired, for property "Name"
        Items[0].Name = "Foo";
    }
}

[olegul86]

Hello! Kind of you to keep responding.

I have understood the error in my ways, to some degree. I kept trying to bind the textbox input to my LicenseHolder.cs (Model holder class which populates my DataGrid), I understand now that my implementations were silly, as they had no way to hold the text inputs.
I have been trying to implement full properties to hold the textbox inputs (not in my code presently), but I can't get it to work, e.g:

private string _foretaksnavn;

public string Foretaksnavn {
    get { return _foretaksnavn; }
    set { _foretaksnavn = value; }
}

Also, I do not know how to get rid of referencing the View in the following code when I try to add to the Sql server table:

AddView view = Application.Current.Windows.OfType<AddView>().FirstOrDefault();
sqlCmd.Parameters.AddWithValue("@Foretaksnavn", view.txtForetaksnavn.Text.ToString());

Yeah, this is tangled up in all sorts of ways. If you could help me untangle it, I'd be very grateful.

Please see all of my code below:

AddViewModel (formerly known as AddLicenseHolderViewModel)

using System;
using System.Data.SqlClient;
using System.Linq;
using System.Windows;
using Ridel.Hub.Views;
using Stylet;

namespace Ridel.Hub.ViewModels {
    public class AddViewModel : Conductor<IScreen>.StackNavigation {

        private readonly IWindowManager windowManager;

        public BindableCollection<LicenseHolder> LicenseHolders;

        #region Constructor
        public AddViewModel(IWindowManager windowManager) {

            this.windowManager = windowManager;
            LicenseHolders = new BindableCollection<LicenseHolder>();
        }
        #endregion // Constructor

        #region Add DataGrid row
        public void AddLicenseHolder() {

            //TO-DO: Legg til exceptionhandler hvis noen textbokser er tomme.

            string sqlString = "insert into tblLicenseHolder (Foretaksnavn, Foretaksnummer, Adresse, Postnummer, Poststed, BIC, IBAN, Kontakt, Epost, Tlf, Kontonummer) " +
                "values (@Foretaksnavn, @Foretaksnummer, @Adresse, @Postnummer, @Poststed, @BIC, @IBAN, @Kontakt, @Epost, @Tlf, @Kontonummer)";

            try {

                using (SqlConnection sqlCon = new(ConnectionString.connectionString))
                using (SqlCommand sqlCmd = new(sqlString, sqlCon)) {

                    sqlCon.Open();

                    AddView view = Application.Current.Windows.OfType<AddView>().FirstOrDefault();

                    sqlCmd.Parameters.AddWithValue("@Foretaksnavn", view.txtForetaksnavn.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Foretaksnummer", view.txtForetaksnr.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Adresse", view.txtAdresse.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Postnummer", view.txtPostnummer.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Poststed", view.txtPoststed.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@BIC", view.txtBIC.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@IBAN", view.txtIBAN.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Kontakt", view.txtKontakt.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Epost", view.txtEpost.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Tlf", view.txtTlf.Text.ToString());
                    sqlCmd.Parameters.AddWithValue("@Kontonummer", view.txtKontonr.Text.ToString());
                    sqlCmd.ExecuteNonQuery();
                }

                LicenseHolders.AddRange(LicenseHolders);
                NotifyOfPropertyChange(() => LicenseHolders);
                LicenseHolders.Refresh();

                MessageBox.Show("Ny løyvehaver lagret.");

                this.RequestClose(true);

            } catch (Exception ex) {

                MessageBox.Show(ex.Message, "Message", MessageBoxButton.OK, MessageBoxImage.Information);
            }
        }
        #endregion // Add DataGrid row
    }
}

AddView - I removed some of it (formerly known as AddLicenseHolderView)

<Window x:Class="Ridel.Hub.Views.AddView"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Ridel.Hub.Views"
        xmlns:s="https://github.com/canton7/Stylet" xmlns:viewmodels="clr-namespace:Ridel.Hub.ViewModels" 
        Title=""
        Width="736"
        Height="562"
        MaxWidth="800"
        MaxHeight="800"
        HorizontalAlignment="Right"
        VerticalAlignment="Bottom"
        Background="#f7f7f7"
        FontSize="48"
        ResizeMode="NoResize"
        ShowInTaskbar="False"
        WindowStartupLocation="CenterScreen"
        mc:Ignorable="d" >

        <TextBox
            Name="txtKontakt"
            Canvas.Left="464"
            Canvas.Top="164"
            Width="180"
            Height="24"
            Text="{Binding Path=Kontakt}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtTlf"
            Canvas.Left="464"
            Canvas.Top="200"
            Width="180"
            Height="24"
            Text="{Binding Path=Tlf}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtEpost"
            Canvas.Left="464"
            Canvas.Top="234"
            Width="180"
            Height="24"
            Text="{Binding Path=Epost}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtForetaksnavn"
            Canvas.Left="150"
            Canvas.Top="166"
            Width="180"
            Height="24"
            Text="{Binding Path=Foretaksnavn}"
            VerticalContentAlignment="Center"            
            FontSize="14" />
        <TextBox
            Name="txtForetaksnr"
            Canvas.Left="150"
            Canvas.Top="203"
            Width="180"
            Height="24"
            Text="{Binding Path=Foretaksnummer}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtAdresse"
            Canvas.Left="150"
            Canvas.Top="241"
            Width="180"
            Height="24"
            Text="{Binding Path=Adresse}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtPoststed"
            Canvas.Left="150"
            Canvas.Top="279"
            Width="180"
            Height="25"
            Text="{Binding Path=Poststed}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtPostnummer"
            Canvas.Left="261"
            Canvas.Top="317"
            Width="71"
            Height="24"
            Text="{Binding Path=Postnummer}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtBIC"
            Canvas.Left="152"
            Canvas.Top="357"
            Width="180"
            Height="24"
            Text="{Binding Path=BIC}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtIBAN"
            Canvas.Left="151"
            Canvas.Top="393"
            Width="180"
            Height="24"
            Text="{Binding Path=IBAN}"
            VerticalContentAlignment="Center"
            FontSize="14" />
        <TextBox
            Name="txtKontonr"
            Canvas.Left="150"
            Canvas.Top="429"
            Width="180"
            Height="24"
            Text="{Binding Path=Kontonummer}"
            VerticalContentAlignment="Center"
            FontSize="14" />

        <Button
            Name="btnLagre"
            Canvas.Left="528"
            Canvas.Top="423"
            Width="116"
            Height="30"
            HorizontalContentAlignment="Center"
            Background="#48bb88"
            Content="Lagre"
            FontSize="16"
            Command="{s:Action AddLicenseHolder}"
            Foreground="White" Style="{DynamicResource RoundedButtonStyle}">
        </Button>
</Window>

LicenseHolderViewModel (parent view-model with the DataGrid)

using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows;
using GalaSoft.MvvmLight.Command;
using Stylet;

namespace Ridel.Hub.ViewModels {
    public class LicenseHolderViewModel : Conductor<IScreen>.StackNavigation {

        private readonly IWindowManager windowManager;

        public BindableCollection<LicenseHolder> LicenseHolders { get; set; }

        #region Constructor
        public LicenseHolderViewModel(IWindowManager windowManager) {

            this.windowManager = windowManager;
            LicenseHolders = new BindableCollection<LicenseHolder>();
        }
        #endregion // Constructor

        #region Populate DataGrid
        public void FillDataGridLicenseHolders() {
            // Fyller DataGrid med oppdatert liste over Løyvehavere fra databasen

            try {

                using (SqlConnection sqlCon = new(ConnectionString.connectionString))
                using (SqlCommand sqlCmd = new("select * from tblLicenseHolder", sqlCon))
                using (SqlDataAdapter sqlDaAd = new(sqlCmd))
                using (DataSet ds = new()) {

                    sqlCon.Open();
                    sqlDaAd.Fill(ds, "tblLicenseHolder");

                    foreach (DataRow dr in ds.Tables[0].Rows) {

                        LicenseHolders.Add(new LicenseHolder {

                            ID = Convert.ToInt32(dr[0].ToString()),
                            Foretaksnavn = dr[1].ToString(),
                            Foretaksnummer = dr[2].ToString(),
                            Adresse = dr[3].ToString(),
                            Postnummer = dr[4].ToString(),
                            Poststed = dr[5].ToString(),
                            BIC = dr[6].ToString(),
                            IBAN = dr[7].ToString(),
                            Kontakt = dr[8].ToString(),
                            Epost = dr[9].ToString(),
                            Tlf = dr[10].ToString(),
                            Kontonummer = dr[11].ToString()
                        });
                    }                  
                }

            } catch (Exception ex) {

                MessageBox.Show(ex.Message, "Message", MessageBoxButton.OK, MessageBoxImage.Information);
            }
        }
        #endregion // Populate DataGrid

        #region Delete DataGrid row
        //TO-DO: Re-write using Stylet functionality
        private static bool RemoveFromDB(LicenseHolder myLicenseHolder) {
            // Sletter valgt løyvehaver fra databasen

            string sqlString = $"Delete from tblLicenseHolder where ID = '{myLicenseHolder.ID}'";

            // TO-DO: Legg inn navn på valgt løyvehaver i MessageBox
            if (MessageBox.Show("Er du sikker på at du ønsker å slette valgt løyvehaver?", "Slett løyvehaver", MessageBoxButton.YesNo, MessageBoxImage.Warning) == MessageBoxResult.Yes) {

                try {

                    using (SqlConnection sqlCon = new(ConnectionString.connectionString))
                    using (SqlCommand sqlCmd = new(sqlString, sqlCon)) {

                        sqlCon.Open();
                        sqlCmd.ExecuteNonQuery();
                        return true;
                    }

                }
                catch {

                    return false;
                }

            } else {

                return false;
            }
        }

        private void RemoveLicenseHolderExecute(LicenseHolder myLicenseHolder) {

            // Hvis spesifisert løyvehaver fjernes fra databasen, da også fjern den fra BindableCollection
            bool result = RemoveFromDB(myLicenseHolder);
            if (result)
                LicenseHolders.Remove(myLicenseHolder);
        }

        private RelayCommand<LicenseHolder> _removeLicenseHoldersCommand;

        public RelayCommand<LicenseHolder> RemoveLicenseHoldersCommand => _removeLicenseHoldersCommand
            ??= new RelayCommand<LicenseHolder>(RemoveLicenseHolderExecute/*, RemoveLicenseHolderCanExecute*/);

        //private bool RemoveLicenseHolderCanExecute(LicenseHolder myLicenseHolder) {

        //    // Sjekker BindableCollection etter den spesifiserte løyvehaveren
        //    return LicenseHolders.Contains(myLicenseHolder);
        //}

        #endregion // Delete DataGrid Row

        #region GUI stuff
        public void ShowLicenseHolderDialog() {

            var viewModel = new AddViewModel(windowManager);
            bool? result = this.windowManager.ShowDialog(viewModel);

            if (result.GetValueOrDefault(true)) {

            }
        }

        public void ShowAddViewDialog() {

            var viewModel = new AddViewModel(windowManager);
            bool? result = this.windowManager.ShowDialog(viewModel);

            if (result.GetValueOrDefault(true)) {

            }
        }

        public void ShowProfileViewDialog() {

            var viewModel = new ProfileViewModel(windowManager);
            bool? result = this.windowManager.ShowDialog(viewModel);

            if (result.GetValueOrDefault(true)) {

            }
        }

        public void LogOut() {

            CloseAllWindows.ClosingAllWindows();
        }
        #endregion // GUI stuff
    }
}

LicenseHolderView (you didn't ask for this, but just in case)

<Window
    x:Class="Ridel.Hub.Views.LicenseHolderView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:local="clr-namespace:Ridel.Hub"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:s="https://github.com/canton7/Stylet"
    Title=""
    Width="800"
    Height="800"
    MaxWidth="800"
    MaxHeight="800"
    HorizontalAlignment="Right"
    VerticalAlignment="Bottom"
    Background="#f7f7f7"
    FontSize="48"
    ResizeMode="NoResize"
    ShowInTaskbar="False"
    WindowStartupLocation="CenterScreen"
    mc:Ignorable="d">

    <Canvas Margin="10,10,10,10">

        <Button
            x:Name="btnLogOut"
            Canvas.Left="547"
            Canvas.Top="17"
            Width="233"
            Height="31"
            Margin="0,0,0,20"
            Command="{s:Action LogOut}"
            Content="LoggedInUser"
            FontSize="14"
            Style="{DynamicResource ButtonWithOnlyText}" />

        <Button
            x:Name="btnNew"
            Canvas.Left="547"
            Canvas.Top="114"
            Width="187"
            Height="41"
            Background="#48bb88"
            Content="Ny løyvehaver"
            FontSize="22"
            Foreground="White"
            Command="{s:Action ShowAddViewDialog}"
            Style="{DynamicResource RoundedButtonStyle}" />

        <!-- TO-DO: slett command kan omskrives ihht. Stylet sine funksjoner -->
        <Button
            x:Name="btnDelete"
            Canvas.Left="547"
            Canvas.Top="674"
            Width="187"
            Height="41"
            Background="#48bb88"
            Content="Slett løyvehaver"
            FontSize="22"
            Foreground="White"                   
            IsEnabled="False"
            Command="{Binding RemoveLicenseHoldersCommand}"
            CommandParameter="{Binding SelectedItem, ElementName=dgLicenseHolder}"
            Style="{DynamicResource RoundedButtonStyle}" />

        <Button
            x:Name="btnProfile"
            Canvas.Left="547"
            Canvas.Top="160"
            Width="187"
            Height="41"
            Background="#48bb88"
            Content="Se profil"
            FontSize="22"
            Foreground="White"
            Command="{s:Action ShowProfileViewDialog}"          
            DataContext="{Binding SelectedItem}"
            IsEnabled="False"
            Style="{DynamicResource RoundedButtonStyle}" />

        <DataGrid
            x:Name="dgLicenseHolder"
            Canvas.Left="31"
            Canvas.Top="158"
            Width="505"
            Height="557"
            AutoGenerateColumns="False"
            BorderBrush="#48bb88"
            CanUserAddRows="False"
            CanUserDeleteRows="False"
            FontSize="20"
            IsReadOnly="True"
            Loaded="{s:Action FillDataGridLicenseHolders}"
            ItemsSource="{Binding LicenseHolders, Mode=TwoWay}"
            SelectedItem="{Binding SelectedRow, Mode=TwoWay}"
            SelectionMode="Single" SelectionChanged="dgLicenseHolder_SelectionChanged" >

            <DataGrid.Columns>
                <DataGridTextColumn
                    Header="ID"
                    IsReadOnly="True"
                    Visibility="Collapsed" 
                    Binding="{Binding Path=ID}"/>
                <DataGridTextColumn
                    Width="310"
                    Header="Foretaksnavn"
                    HeaderStyle="{StaticResource CenterGridHeaderStyle}"
                    IsReadOnly="True"
                    Visibility="Visible" 
                    Binding="{Binding Path=Foretaksnavn}"/>
                <DataGridTextColumn
                    Header="Foretaksnummer"
                    IsReadOnly="True"
                    Visibility="Collapsed" 
                    Binding="{Binding Path=Foretaksnummer}"/>
                <DataGridTextColumn
                    Header="Adresse"
                    IsReadOnly="True"
                    Visibility="Collapsed"
                    Binding="{Binding Path=Adresse}"/>
                <DataGridTextColumn
                    Header="Postnummer"
                    IsReadOnly="True"
                    Visibility="Collapsed"
                    Binding="{Binding Path=Postnummer}"/>
                <DataGridTextColumn
                    Width="*"
                    Header="Poststed"
                    HeaderStyle="{StaticResource CenterGridHeaderStyle}"
                    IsReadOnly="True"
                    Visibility="Visible"
                    Binding="{Binding Path=Poststed}"/>
                <DataGridTextColumn
                    Header="BIC"
                    IsReadOnly="True"
                    Visibility="Collapsed"
                    Binding="{Binding Path=BIC}"/>
                <DataGridTextColumn
                    Header="IBAN"
                    IsReadOnly="True"
                    Visibility="Collapsed" 
                    Binding="{Binding Path=IBAN}"/>
                <DataGridTextColumn
                    Header="Kontakt"
                    IsReadOnly="True"
                    Visibility="Collapsed"
                    Binding="{Binding Path=Kontakt}"/>
                <DataGridTextColumn
                    Header="Epost"
                    IsReadOnly="True"
                    Visibility="Collapsed"
                    Binding="{Binding Path=Epost}"/>
                <DataGridTextColumn
                    Header="Tlf"
                    IsReadOnly="True"
                    Visibility="Collapsed"
                    Binding="{Binding Path=Tlf}"/>
                <DataGridTextColumn
                    Header="Kontonummer"
                    IsReadOnly="True"
                    Visibility="Collapsed" 
                    Binding="{Binding Path=Kontonummer}"/>
            </DataGrid.Columns>
        </DataGrid>
</Window>

[olegul86]

Okay, so I tried implementing your examples. I changed LicenseHolder.cs to the following:

 public class LicenseHolder : INotifyPropertyChanged {

        public event PropertyChangedEventHandler PropertyChanged;

        private int _id;
        public int ID {
            get { return _id; }
            set { _id = value; }
        }

        private string _foretaksnavn;
        public string Foretaksnavn {
            get { return _foretaksnavn; }
            set { _foretaksnavn = value; }
        }

        private string _foretaksnummer;
        public string Foretaksnummer {
            get { return _foretaksnummer; }
            set { _foretaksnummer = value; }
        }

        private string _adresse;
        public string Adresse {
            get { return _adresse; }
            set { _adresse = value; }
        }

        private string _postnummer;
        public string Postnummer {
            get { return _postnummer; }
            set { _postnummer = value; }
        }

        private string _poststed;
        public string Poststed {
            get { return _poststed; }
            set { _poststed = value; }
        }

        private string _bic;
        public string BIC {
            get { return _bic; }
            set { _bic = value; }
        }

        private string _iban;
        public string IBAN {
            get { return _iban; }
            set { _iban = value; }
        }

        private string _kontakt;
        public string Kontakt {
            get { return _kontakt; }
            set { _kontakt = value; }
        }

        private string _epost;
        public string Epost {
            get { return _epost; }
            set { _epost = value; }
        }

        private string _tlf;
        public string Tlf {
            get { return _tlf; }
            set { _tlf = value; }
        }

        private string _kontonummer;
        public string Kontonummer {
            get { return _kontonummer; }
            set { _kontonummer = value; }
        }
    }

I'm not entirely sure if that matters, compared to how I used to set it up (just public string Foretaksnavn { get; set; }).

And then I added these to my AddViewModel, in my AddLicenseHolder() method, beneath my AddWithValue code block:

LicenseHolders = new BindableCollection<LicenseHolder>();
LicenseHolders.Add(new LicenseHolder());
LicenseHolders[0].Foretaksnavn = "Foretaksnavn";
LicenseHolders[1].Foretaksnummer = "Foretaksnummer";
LicenseHolders[2].Adresse = "Adresse";
LicenseHolders[3].Postnummer = "Postnummer";
LicenseHolders[4].Poststed = "Poststed";
LicenseHolders[5].BIC = "BIC";
LicenseHolders[6].IBAN = "IBAN";
LicenseHolders[7].Kontakt = "Kontakt";
LicenseHolders[8].Epost = "Epost";
LicenseHolders[9].Tlf = "Tlf";
LicenseHolders[10].Kontonummer = "Kontonummer";

And when I open my application, and try adding a new row to the DataGrid, I get this error message:

Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index').

Could that have to do with the fact that all but two columns are collapsed (in the XAML)? UPDATE: It did not have to do with collapsed columns.... :-)

[canton7]

I'll look properly tomorrow, but:

1. You're not raising the PropertyChanged event. Look at PropertyChangedBase on the wiki
2. You're accessing LicenseHolders[1], [2], etc, but you've only got 1 element in LicenseHolders.

[olegul86]

Thank you for the pointers!
Your time is still very much appreciated.
I added PropertyChangedBase to LicenseHolder.cs, like so:

public class LicenseHolder : PropertyChangedBase {

    private int _foretaksnavn;
    public int Foretaksnavn{

        get { return this._foretaksnavn; }
        set { SetAndNotify(ref this._foretaksnavn, value); }
    }
}

I changed all the element counters to [0].

I assumed I also needed to add PropertyChangedBase to AddViewModel. But since it already has a base class: Conductor<IScreen>.StackNavigation, I was not able to add more base classes.
So I added it beneath, like so:

public class PropertyChangedBase { }

and that doesn't feel right, it just sitting there...

But I did, in the same AddViewModel, change my instantiation of the BindableCollection to the way you suggested:

private BindableCollection<LicenseHolder> _licenseHolders;
public BindableCollection<LicenseHolder> LicenseHolders {
    get => _licenseHolders;
   set => SetAndNotify(ref _licenseHolders, value);
}

Also, I added d:DataContext="{d:DesignInstance Type=hub:LicenseHolder}" to the AddView XAML.
And so, when I run my code, the following happens:

If I comment out my sql server AddWithValue code block

• My DataGrid row does not immediately update, and when I re-open the window, the columns are filled with the string value I declared in the AddLicenseHolder() method, f.ex: "Foretaksnavn". Hm... No PropertyChanged triggering?
• If I leave my Sql server AddWithValue code block, it's just business as usual, it saves the data, but only updates the DataGrid when I re-open the window.

[canton7]

Just stop and take a step back, please. You're making seemingly random changes, before I've even had a chance to catch up with the load of code you dumped on me previously.

Let's just simplify this a bit. You've got:

1. LicenseHolderView/ViewModel, which has the DataGrid with the list of license holders.
2. AddView/ViewModel, which lets the user add a new licence holder.

When the user clicks a button in LicenseHolderView, we show AddView. When they add a new license holder with AddView, we update the DataGrid.

Does that sound about right?

We've got a choice as to where we do the insertion into the database: in LicenseHolderView or in AddView. Let's do it in AddView, but either would work. We'll then need a way for AddView to signal to LicenseHolderView that it's added a new license holder, and that it should update its list: let's simply use the DialogResult, true if we added a new license holder, false if we didn't.

So, a cut-down version:

public class LicenseHolderViewModel
{
    private readonly IWindowManager windowManager;

    public BindableCollection<LicenseHolder> LicenseHolders { get; } = new();

    public void LoadLicenseHolders()
    {
        LicenseHolders.Clear();

        // SQL, etc, etc
        foreach (...)
        {
            LicenseHolders.Add(new LicenseHolder(...));
        }
    }

    public void ShowAdd()
    {
        bool? result = windowManager.ShowDialog(new AddLicenseViewModel(...));
        if (result == true)
        {
            // We added a new license holder: reload our list
            LoadLicenseHolders();
        }
    }
}

public class AddViewModel : Screen
{
    private string _foretaksnavn;
    public string Foretaksnavn
    {
        get => _foretaksnavn;
        set => SetAndNotify(ref _foretaksnavn, value);
    }

    // Etc, for all fields we want the user to fill in

    public void Add()
    {
        // SQL, etc, etc
        // Access the properties
        sqlCmd.Parameters.AddWithValue("@Foretaksnavn", Foretaksnavn);
        // Execute
        // Tell LicenseHolderViewModel that it needs to reload
        RequestClose(true);
    }

    public void Cancel()
    {
        // Tell LicenseHolderViewModel it doesn't need to reload
        RequestClose(false);
    }
}

<Window x:Class="...AddView" ...>
    <TextBox Text="{Binding Foretaksnavn}"/>
    <!-- ... -->
</Window>

---

Does that make sense?

LicenseHolderViewModel has the BindableCollection of LicenseHolder. It opens AddViewModel. AddViewModel has properties for each of the fields we want the user to fill in, and those are bound to TextBoxes in the view. When it wants to insert a new record into the database, it reads from each of those properties, constructs the SQL query, executes it, and returns with 'true' to call LicenseHolderViewModel to reload.

[olegul86]

Antony, thank you so much - that did it! Works like a charm!

I was able to take many lines off my code, and your explanation really helped me get a better understanding for something I've been struggling with for way to long. I am really grateful - I have tried so many different solutions found throughout the web, but nothing did it for me, I just got more and more confused trying to add implementation upon implementation. But now it finally clicked. I'm buying you a big, fat, double cortado for this...

One more additional question: do I really need the getter/setters in two locations, both in my LicenseHolder.cs, and in the AddViewModel as well..? Is there no way to get both LicenseHolderViewModel and AddViewModel both what they need from one source?

I will try to get that working, unless there's a obvious reason I shouldn't?

[canton7]

Thanks! Yeah my impression was that you were in a bit of a muddle: you had two LicenseHolders collections for instance, one of which wasn't bound to anything.

What do you mean by "the getter/setters in two locations"? Where in my example do I have that?