Implemented export to CSV functionality.

PcgsInvUi/Services/Database.cs

@@ -121,6 +121,55 @@ public class Database {
         
         return coins;
     }
+
+    public String CollectionToCSV(string collectionName) {
+        var cmd = Connection.CreateCommand();
+        cmd.CommandText = $"SELECT * FROM {collectionName}";
+
+        var headersCommand = Connection.CreateCommand();
+        headersCommand.CommandText = $"PRAGMA table_info({collectionName})";
+        
+        var resultString = "";
+        var numHeaders = 0;
+        
+        // Get the headers.
+        using (var reader = headersCommand.ExecuteReader()) {
+            while (reader.Read()) {
+                resultString += reader.GetString(1) + ",";
+                numHeaders++;
+            }
+        }
+
+        resultString += "\n";
+
+        // Is there a more efficient way of doing this? This is running at O(n^2) time.
+        using (var reader = cmd.ExecuteReader()) {
+            while (reader.Read()) {
+                // Read information from the reader, then add to CSV string.
+                for (int i = 0; i < numHeaders; i++) {
+                    // Get the type of each column.
+                    var type = reader.GetFieldType(i);
+                    Console.WriteLine("Type: " + type);
+                    if (type == typeof(Int64)) {
+                        resultString += reader.GetInt32(i) + ",";
+                    }
+                    else if (type == typeof(Double)) {
+                        resultString += reader.GetDouble(i) + ",";
+                    }
+                    else if (type == typeof(String)) {
+                        resultString += reader.GetString(i) + ",";
+                    }
+                    else {
+                        resultString += "NULL" + ",";
+                    }
+                }
+
+                resultString += "\n";
+            }
+        }
+
+        return resultString;
+    }
     
     public Coin? GetCoin(int pcgsNumber, string grade) {
         // Get the coin based off of the pcgs number.

PcgsInvUi/ViewModels/MainWindowViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.ObjectModel;
+using System.IO;
 using System.Linq;
 using System.Reactive;
 using System.Reactive.Linq;
@@ -9,8 +10,6 @@ using ReactiveUI;
 
 namespace PcgsInvUi.ViewModels;
 
-// TODO Find window.
-// TODO Export window and export function.
 // TODO Error handling.
 // TODO Manual handling of API key.
 // TODO Use CoinFacts link.
@@ -43,6 +42,8 @@ public class MainWindowViewModel : ViewModelBase {
     public Interaction<DeleteWindowViewModel, Boolean> ShowDeleteWindow { get; }
     public ReactiveCommand<Unit, Coin> FindCommand { get; }
     public Interaction<FindWindowViewModel, int> ShowFindWindow { get; }
+    public ReactiveCommand<Unit, Unit> ExportCommand { get; }
+    public Interaction<Unit, Stream> ShowExportWindow { get; }
 
     private ViewModelBase _sideContent;
     private Coin? _selectedCoin;
@@ -67,12 +68,29 @@ public class MainWindowViewModel : ViewModelBase {
         DeleteCommand = ReactiveCommand.CreateFromTask(async () => {
             var deleteViewModel = new DeleteWindowViewModel();
             var result = await ShowDeleteWindow.Handle(deleteViewModel);
-            if (result && SelectedCoin != null) {
+            if (result && SelectedCoin is not null) {
                 ConnectedDatabase.DeleteCoin(SelectedCoin);
                 CoinCollection.Remove(SelectedCoin); // possible null deref - ignored due to button being disabled.
             }
         }, deleteEnabled);
 
+        ShowExportWindow = new Interaction<Unit, Stream>();
+        ExportCommand = ReactiveCommand.CreateFromTask(async () => {
+            var stream = await ShowExportWindow.Handle(Unit.Default);
+            var writer = new StreamWriter(stream);
+            try {
+                await writer.WriteAsync(ConnectedDatabase.CollectionToCSV("CollectionTable"));
+                await writer.FlushAsync();
+            }
+            catch (IOException e) {
+                // Something is wrong with the file after it's been created.
+                Console.WriteLine(e.Message);
+            }
+
+            writer.Close();
+            stream.Close();
+        });
+        
         // Set up the ability to open the find window.
         ShowFindWindow = new Interaction<FindWindowViewModel, int>();
         var findEnabled = this.WhenAnyValue(x => x.CoinCollection.Count,
@@ -84,7 +102,7 @@ public class MainWindowViewModel : ViewModelBase {
             // Perhaps a secondary viewmodel?
             return new Coin();
         }, findEnabled);
-
+        
         // Subscribe to SidebarContent.OkCommand, which is an IObservable<(int, string, int)>
         // This is the same as the above, but with a different syntax.
         newViewModel.OkCommand

PcgsInvUi/Views/MainWindow.axaml

@@ -65,16 +65,16 @@
                       DockPanel.Dock="Left">
                     <Button Grid.Column="0" Margin="5" Width="100" HorizontalContentAlignment="Center" Content="Delete"
                             Command="{Binding DeleteCommand}" />
-                    <Button Grid.Column="1" Margin="5" Width="100" HorizontalContentAlignment="Center"
+                    <!-- <Button Grid.Column="1" Margin="5" Width="100" HorizontalContentAlignment="Center" -->
-                            Content="Find..."
+                    <!--         Content="Find..." -->
-                            Command="{Binding FindCommand}" />
+                    <!--         Command="{Binding FindCommand}" /> -->
                 </Grid>
                 <Grid HorizontalAlignment="Right" VerticalAlignment="Bottom" Margin="5" ColumnDefinitions="Auto, Auto"
                       DockPanel.Dock="Right">
                     <Label Grid.Column="0" Margin="5" VerticalAlignment="Center"
                            Content="{Binding TotalValue, StringFormat='Total Value: ${0:0.00}'}" />
                     <Button Grid.Column="1" Margin="5" Width="150" HorizontalContentAlignment="Center"
-                            Content="Export to CSV..." />
+                            Content="Export to CSV..." Command="{Binding ExportCommand}" />
                 </Grid>
             </DockPanel>
         </Grid>

PcgsInvUi/Views/MainWindow.axaml.cs

@@ -1,5 +1,8 @@
 using System;
+using System.IO;
+using System.Reactive;
 using System.Threading.Tasks;
+using Avalonia.Platform.Storage;
 using Avalonia.ReactiveUI;
 using PcgsInvUi.ViewModels;
 using ReactiveUI;
@@ -10,7 +13,8 @@ public partial class MainWindow : ReactiveWindow<MainWindowViewModel> {
     public MainWindow() {
         InitializeComponent();
         this.WhenActivated(d => d(ViewModel!.ShowDeleteWindow.RegisterHandler(ShowDeleteWindowAsync)));
-        this.WhenActivated(d => d(ViewModel!.ShowFindWindow.RegisterHandler(ShowFindWindowAsync)));
+        this.WhenActivated(d => d(ViewModel!.ShowExportWindow.RegisterHandler(ShowFilePickerAsync)));
+        // this.WhenActivated(d => d(ViewModel!.ShowFindWindow.RegisterHandler(ShowFindWindowAsync)));
     }
 
     public async Task ShowDeleteWindowAsync(InteractionContext<DeleteWindowViewModel, Boolean> interaction) {
@@ -28,4 +32,22 @@ public partial class MainWindow : ReactiveWindow<MainWindowViewModel> {
         var result = await window.ShowDialog<int>(this);
         interaction.SetOutput(result);
     }
+
+    public async Task ShowFilePickerAsync(InteractionContext<Unit, Stream> interationContext) {
+        var topLevel = GetTopLevel(this);
+        var file = await topLevel.StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions {
+            Title = "Save CSV...",
+            DefaultExtension = ".csv",
+            ShowOverwritePrompt = true,
+            SuggestedFileName = "coins.csv",
+            SuggestedStartLocation = await StorageProvider.TryGetWellKnownFolderAsync(WellKnownFolder.Documents)
+        });
+
+        Stream stream;
+        
+        if (file is not null) {
+            stream = await file.OpenWriteAsync();
+            interationContext.SetOutput(stream);
+        }
+    }
 }