C# Avalonia 19- DataBinding- BindToLinqFilteredCollection

BindToLinqFilteredCollection.axaml代码

<Window xmlns="https://github.com/avaloniaui"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"Width="360" Height="500"xmlns:local="using:AvaloniaUI.Demos.Book._19.StoreDatabase"x:Class="AvaloniaUI.BindToLinqFilteredCollection"Title="BindToLinqFilteredCollection"><Grid RowDefinitions="*,auto,*"><Grid RowDefinitions="*,auto,auto"><ListBox Name="lstProducts" Margin="5,0" DisplayMemberBinding="{Binding ModelName}" x:DataType="local:Product"></ListBox><StackPanel Grid.Row="1" Orientation="Horizontal" Margin="5,2,5,5" HorizontalAlignment="Right"><TextBlock VerticalAlignment="Center">Minimum Cost:</TextBlock><TextBox Name="txtMinimumCost" Margin="5,0" Width="40" Text="100" TextChanged="txt_TextChanged"></TextBox></StackPanel><StackPanel Grid.Row="2" HorizontalAlignment="Right" Orientation="Horizontal" Margin="5,2,5,10"><Button Margin="2,0,0,0"  Padding="2"Click="cmdDeleteProduct_Click">Delete Selected</Button><Button Margin="2,0,0,0"Click="cmdAddProduct_Click" Padding="2">Add New</Button></StackPanel>        </Grid><GridSplitter Grid.Row="2" HorizontalAlignment="Stretch" VerticalAlignment="Bottom"ResizeBehavior="PreviousAndNext" Height="5"/><Border Grid.Row="3" Padding="7" Margin="7" Background="LightSteelBlue"><Grid DataContext="{Binding #lstProducts.SelectedItem}" x:DataType="local:Product"ColumnDefinitions="auto,*" RowDefinitions="auto,auto,auto,auto,*"><TextBlock Margin="7">Model Number:</TextBlock><TextBox Margin="5" Grid.Column="1" Text="{Binding ModelNumber}"></TextBox><TextBlock Margin="7" Grid.Row="1">Model Name:</TextBlock><TextBox Margin="5" Grid.Row="1" Grid.Column="1" Text="{Binding ModelName}"></TextBox><TextBlock Margin="7" Grid.Row="2">Unit Cost:</TextBlock><TextBox Margin="5" Grid.Row="2" Grid.Column="1" Text="{Binding UnitCost}"></TextBox><TextBlock Margin="7,7,7,0" Grid.Row="3">Description:</TextBlock><ScrollViewer Grid.Row="4" Grid.Column="0" Grid.ColumnSpan="2"><TextBox Margin="7" TextWrapping="Wrap" Text="{Binding Description}"></TextBox></ScrollViewer></Grid></Border></Grid>
</Window>

BindToLinqFilteredCollection.axaml.cs代码

using Avalonia;
using Avalonia.Controls;
using Avalonia.Interactivity;
using Avalonia.Markup.Xaml;
using Avalonia.Media;
using AvaloniaUI.Demos.Book._19.StoreDatabase;
using System.Collections.ObjectModel;
using System.Linq;namespace AvaloniaUI;public partial class BindToLinqFilteredCollection : Window
{private readonly StoreDb1 db = new();// 保留所有产品（包括 Add 的）private ObservableCollection<Product> allProducts = new();// 用于 UI 显示的过滤结果private ObservableCollection<Product> filteredProducts = new();public BindToLinqFilteredCollection(){InitializeComponent();// 初始化加载所有产品allProducts = db.GetProducts();// 初始过滤ApplyFilter();}private void ApplyFilter(){filteredProducts.Clear();if (!decimal.TryParse(txtMinimumCost.Text, out var min))min = 0;foreach (var p in allProducts.Where(p => p.UnitCost >= min))filteredProducts.Add(p);lstProducts.ItemsSource = filteredProducts;}private void cmdDeleteProduct_Click(object? sender, RoutedEventArgs e){if (lstProducts.SelectedItem is Product p){allProducts.Remove(p);filteredProducts.Remove(p);}}private void cmdAddProduct_Click(object? sender, RoutedEventArgs e){var newP = new Product("00000", "?", 0, "?");allProducts.Add(newP);// 如果通过过滤则显示ApplyFilter();}private void txt_TextChanged(object? sender, TextChangedEventArgs e){// 判断是否为数字if (!decimal.TryParse(txtMinimumCost.Text, out _))txtMinimumCost.Foreground = Brushes.Red;elsetxtMinimumCost.Foreground = Brushes.Black;// 重新应用过滤ApplyFilter();}
}

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