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	<uses-permission android:name="android.permission.READ_CONTACTS" />

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using Xamarin.Forms;

namespace Controls
{
    public class CheckBox : StackLayout
    {
        BoxView boxBackground = new BoxView { HeightRequest = 25, WidthRequest = 25, BackgroundColor = Color.LightGray, VerticalOptions = LayoutOptions.CenterAndExpand };
        BoxView boxSelected = new BoxView { IsVisible = false, HeightRequest = 18, WidthRequest = 18, BackgroundColor = Color.Accent, VerticalOptions = LayoutOptions.CenterAndExpand, HorizontalOptions = LayoutOptions.Center };
        Label lblSelected = new Label { Text = "✓", FontSize=19, FontAttributes= FontAttributes.Bold, IsVisible = false, TextColor = Color.Accent, HorizontalOptions = LayoutOptions.Center, VerticalOptions = LayoutOptions.CenterAndExpand };
        Label lblOption = new Label { VerticalOptions = LayoutOptions.CenterAndExpand , FontSize = 14 };

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  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
  </PropertyGroup>

  <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp2.2'">
    <PackageReference Include="Microsoft.AspNetCore" Version="2.2.0" />
    <!-- your .net core 2.2 dependencies here -->
  </ItemGroup>

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#if NETCOREAPP2_2
using Microsoft.AspNetCore;
#endif
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;

namespace Sample.WebService
{
    public class Program
    {

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    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

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public class ProductsController
{
  private readonly MyDbContext context
  public ProductsController(MyDbContext context)
  {
    this.context = context;
  }
  
  [HttpGet]
  public async Task<IActionResult> GetAsync([FromQuery]SomeDto filter)

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    public class Product
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public string Code { get; set; }
        public string Description { get; set; }
        public decimal Price { get; set; }
        public decimal? ShippingPrice { get; set; }
        public int Stock { get; set; }
        public DateTime CreateDate { get; set; }

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var query = db.Products.Where(x => x.Code == filter.Code);

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// x =>
var parameter = Expression.Parameter(typeof(Product), "x"); 

// x => x.Code
var property = Expression.Property(parameter, "Code");

// x.Code == filter.Code
var comparison = Expression.Equal(property, Expression.Constant(filter.Code));

var lambda = Expression.Lambda<Func<Product, bool>>(comparison, parameter);

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var query = db.Products.Where(x => x.Name.Contains(filter.Name))