sample_demo/ServiceApp/ServiceWindow.axaml.cs

using Avalonia;
using Avalonia.Controls;
using Avalonia.Markup.Xaml;
using System.Linq;
using ServiceApp.EnityModels;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using SkiaSharp;
using Microsoft.EntityFrameworkCore.Storage.Json;
using System;
using Npgsql.TypeMapping;
using Avalonia.Media.Imaging;
using Avalonia.Platform;

namespace ServiceApp;

public partial class ServiceWindow : Window
{
    public List<ServicePresenter> sourceList { get; set; }
    public ObservableCollection<ServicePresenter> displayList { get; }

    private string _searchWord = string.Empty;

    private string[] _sortingSource = new string[3] { "îòñóò.", "ïî âîçðàñò.", "ïî óáûâ." };
    private Dictionary<string, (int, int)> _dicountFilter = new Dictionary<string, (int, int)> {
        {"âñå", (0, 0) },
        { "0-5", (0,5)},
        { "15-30", (5,15)},
        { "30-70", (30,70)},
        { "70-100", (70,100)},
    };

    public ServiceWindow()
    {
        InitializeComponent();
        using (var dbContext = new IsajkinContext())
        {

            sourceList = dbContext.Services.Select(service =>
            new ServicePresenter
            {
                Title = service.Title,
                Discount = service.Discount,
                Durationinminutes = service.Durationinminutes,
                Id = service.Id,
                Cost = service.Cost,
                Mainimagepath = service.Mainimagepath,
            }
            ).ToList();
        }
        displayList = new ObservableCollection<ServicePresenter>(sourceList);
        SortingComboBox.ItemsSource = _sortingSource;
        ServiceListBox.ItemsSource = displayList;
        FilteringComboBox.ItemsSource = _dicountFilter.Keys;
        StatisticTextBlock.Text = String.Format("{0} èç {1}", displayList.Count, sourceList.Count);

    }

    private void DisplayService() {

        var displayServiceList = sourceList;
        if (FilteringComboBox.SelectedIndex > 0) displayServiceList = displayServiceList.Where(service => 
        FilterByDiscount(service, FilteringComboBox.SelectionBoxItem.ToString())).ToList();
        if(!String.IsNullOrEmpty(_searchWord)) displayServiceList = displayServiceList.Where(service => SearchByWord(service, _searchWord)).ToList();
        if(SortingComboBox.SelectedIndex > 0) displayServiceList = SortingComboBox.SelectedIndex == 1?
                displayServiceList.OrderBy(service => service.Cost).ToList() :
                displayServiceList.OrderByDescending(service => service.Cost).ToList();
       displayList.Clear();
       foreach (var service in displayServiceList) { displayList.Add(service); }
        StatisticTextBlock.Text = String.Format("{0} èç {1}", displayServiceList.Count, sourceList.Count);
    }


    private bool SearchByWord(ServicePresenter service, string word) {
        if (service.Title.Contains(word, StringComparison.CurrentCultureIgnoreCase)) return true;
        if (String.IsNullOrEmpty(service.Description)) return false;
        if (service.Description.Contains(word, StringComparison.CurrentCultureIgnoreCase)) return true;
        return false;
    }
    private bool FilterByDiscount(ServicePresenter servicePresenter, string key) {
        (int left, int right) = _dicountFilter[key];
        double discount = servicePresenter.Discount != null? Convert.ToDouble(servicePresenter.Discount) * 100 : 0;
        return left <= discount && discount < right;
    }

    private void SearchTextBox_TextChanged(object? sender, Avalonia.Controls.TextChangedEventArgs e)
    {
        _searchWord = SearchTextBox.Text.ToString();
        DisplayService();
    }


    private void FilteringComboBox_SelectionChanged(object? sender, Avalonia.Controls.SelectionChangedEventArgs e)
    {
      DisplayService();
    }

    private void SortingComboBox_SelectionChanged(object? sender, Avalonia.Controls.SelectionChangedEventArgs e)
    {
        DisplayService();
    }
}

public class ServicePresenter() : Service
{
    public int ServiceID { get => this.Id; }
    public string ServiceName { get => this.Title; }
    public string SeviceCostPerSeconds { get =>
            (this.Discount != 0 ?
            String.Format("{0:0.00} ðóáëåé çà {1} ìèíóò", this.Cost - this.Cost * Convert.ToDecimal(this.Discount), this.Durationinminutes)
            :
            String.Format("{0:0.00} ðóáëåé çà {1} ìèíóò", this.Cost, this.Durationinminutes)
            ); 
    }
    public Bitmap ServiceImage { get => GetBitmap(this.Mainimagepath); }
    public decimal? OldCost { get => (this.Discount != 0 ? this.Cost : null); }
    public string? ServiceDiscount { get => 
            (this.Discount != 0 ? 
            String.Format("* ñêèäêà {0}%", Discount * 100)
            : String.Empty
            ); }

    private Bitmap GetBitmap(string fileName) {
        try {
            return new Bitmap($"Assets\\{fileName}");
        }
        catch (Exception ex) {
            return new Bitmap("Assets\\download.png");

        }
    }
}