QueryWindow: Allow users to export query result to csv file

Elwig/Windows/QueryWindow.xaml.cs

@@ -1,7 +1,10 @@
 using Elwig.Helpers;
+using Elwig.Helpers.Export;
+using Microsoft.Win32;
 using System;
 using System.Collections.Generic;
 using System.Data.Common;
+using System.Linq;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
@@ -13,7 +16,12 @@ namespace Elwig.Windows {
 
         private ICommand? _enterCommand;
         public ICommand EnterCommand => _enterCommand ??= new ActionCommand(async () => {
-            await ExecuteQuery();
+            await DisplayQuery();
+        });
+
+        private ICommand? _saveCommand;
+        public ICommand SaveCommand => _saveCommand ??= new ActionCommand(async () => {
+            await SaveQuery();
         });
 
 
@@ -22,33 +30,45 @@ namespace Elwig.Windows {
         }
 
         private async void QueryButton_Click(object sender, RoutedEventArgs evt) {
-            await ExecuteQuery();
+            await DisplayQuery();
         }
 
-        private async Task ExecuteQuery() {
+        private async void SaveButton_Click(object sender, RoutedEventArgs evt) {
+            await SaveQuery();
+        }
+
+        private async Task DisplayQuery() {
             try {
-                await ExecuteQuery(QueryInput.Text);
+                Mouse.OverrideCursor = Cursors.Wait;
+                await DisplayQuery(QueryInput.Text);
+                Mouse.OverrideCursor = null;
             } catch (Exception e) {
+                Mouse.OverrideCursor = null;
                 MessageBox.Show(e.Message, "Fehler beim Ausführen", MessageBoxButton.OK, MessageBoxImage.Error);
             }
         }
 
-        private async Task ExecuteQuery(string sqlQuery) {
+        private async Task SaveQuery() {
+            await SaveQuery(QueryInput.Text);
+        }
+
+        private static async Task<(IList<DbColumn>, IEnumerable<object[]>)> ExecuteQuery(string sqlQuery) {
             var rows = new List<object[]>();
-            IList<DbColumn> header;
-
-            using (var cnx = await AppDbContext.ConnectAsync()) {
-                using var cmd = cnx.CreateCommand();
-                cmd.CommandText = sqlQuery;
-                using var reader = await cmd.ExecuteReaderAsync();
-                header = await reader.GetColumnSchemaAsync();
-                while (await reader.ReadAsync()) {
-                    var values = new object[reader.FieldCount];
-                    reader.GetValues(values);
-                    rows.Add(values);
-                }
+            using var cnx = await AppDbContext.ConnectAsync();
+            using var cmd = cnx.CreateCommand();
+            cmd.CommandText = sqlQuery;
+            using var reader = await cmd.ExecuteReaderAsync();
+            var header = await reader.GetColumnSchemaAsync();
+            while (await reader.ReadAsync()) {
+                var values = new object[reader.FieldCount];
+                reader.GetValues(values);
+                rows.Add(values);
             }
+            return (header, rows);
+        }
 
+        private async Task DisplayQuery(string sqlQuery) {
+            var (header, rows) = await ExecuteQuery(sqlQuery);
             var styleRight = new Style();
             styleRight.Setters.Add(new Setter(TextBlock.TextAlignmentProperty, TextAlignment.Right));
 
@@ -63,5 +83,27 @@ namespace Elwig.Windows {
             }
             DataList.ItemsSource = rows;
         }
+
+        private static async Task SaveQuery(string sqlQuery) {
+            var d = new SaveFileDialog() {
+                FileName = $"Abfrage.csv",
+                DefaultExt = "csv",
+                Filter = "CSV-Datei (*.csv)|*.csv",
+                Title = $"Datenbank Abfrage speichern unter - Elwig"
+            };
+            if (d.ShowDialog() == true) {
+                Mouse.OverrideCursor = Cursors.Wait;
+                await Task.Run(async () => {
+                    try {
+                        var (header, rows) = await ExecuteQuery(sqlQuery);
+                        using var csv = new CsvSimple(d.FileName, ';', Utils.UTF8BOM);
+                        await csv.ExportAsync(rows.Prepend([.. header.Select(h => h.ColumnName)]));
+                    } catch (Exception exc) {
+                        MessageBox.Show(exc.Message, "Fehler beim Ausführen", MessageBoxButton.OK, MessageBoxImage.Error);
+                    }
+                });
+                Mouse.OverrideCursor = null;
+            }
+        }
     }
 }