<div>
    Number Of Clicks <span data-bind="text: numberOfClicks"></span> times
    <button data-bind="click: clickMe">Click me</button>
</div>
 
<script type="text/javascript">
    var viewModel = {
        numberOfClicks : ko.observable(0),
        clickMe: function() {
            var previousCount = this.numberOfClicks();
            this.numberOfClicks(previousCount + 1);
        }
    };
</script>

<ul data-bind="foreach: places">
    <li>
        <span data-bind="text: $data"></span>
        <button data-bind="click: $parent.removePlace">Remove</button>
    </li>
</ul>
 
 <script type="text/javascript">
     function MyViewModel() {
         var self = this;
         self.places = ko.observableArray(['Tehran', 'Esfahan', 'Shiraz']);
 
         self.removePlace = function(place) {
             self.places.remove(place)
         }
     }
     ko.applyBindings(new MyViewModel());
</script>

• هنگامیکه خطایی رخ نداده است، محتوای فرزند خود را رندر می‌کند. 
  
  
• هنگامیکه یک استثناء کنترل نشده رخ می‌دهد، صفحه‌ی خطای پیش فرضی را رندر می‌کند. 

  
  

<div>
    <div>
        <ErrorBoundary>
            @Body
        </ErrorBoundary>
    </div>
</div>

<ErrorBoundary>
    <ChildContent>
        @Body
    </ChildContent>
    <ErrorContent>
        <p class="errorUI">متاسفانه خطایی رخ داده است!</p>
    </ErrorContent>
</ErrorBoundary>

...

<ErrorBoundary @ref="errorBoundary">
    @Body
</ErrorBoundary>

...

@code {
    private ErrorBoundary? errorBoundary;

    protected override void OnParametersSet()
    {
        errorBoundary?.Recover();
    }
}

namespace BlazorWasm.Client.Services
{
    public interface IClientHotelRoomService
    {
        public Task<IEnumerable<HotelRoomDTO>> GetHotelRoomsAsync(DateTime checkInDate, DateTime checkOutDate);
        public Task<HotelRoomDTO> GetHotelRoomDetailsAsync(int roomId, DateTime checkInDate, DateTime checkOutDate);
    }
}

namespace BlazorWasm.Client.Services
{
    public class ClientHotelRoomService : IClientHotelRoomService
    {
        private readonly HttpClient _httpClient;

        public ClientHotelRoomService(HttpClient httpClient)
        {
            _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
        }

        public Task<HotelRoomDTO> GetHotelRoomDetailsAsync(int roomId, DateTime checkInDate, DateTime checkOutDate)
        {
            throw new NotImplementedException();
        }

        public Task<IEnumerable<HotelRoomDTO>> GetHotelRoomsAsync(DateTime checkInDate, DateTime checkOutDate)
        {
            // How to url-encode query-string parameters properly
            var uri = new UriBuilderExt(new Uri(_httpClient.BaseAddress, "/api/hotelroom"))
                            .AddParameter("checkInDate", $"{checkInDate:yyyy'-'MM'-'dd}")
                            .AddParameter("checkOutDate", $"{checkOutDate:yyyy'-'MM'-'dd}")
                            .Uri;
            return _httpClient.GetFromJsonAsync<IEnumerable<HotelRoomDTO>>(uri);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Net.Http.Json;
using System.Threading.Tasks;
using BlazorServer.Models;
using BlazorWasm.Client.Utils;

using System;
using System.Collections.Specialized;
using System.Web;

namespace BlazorWasm.Client.Utils
{
    public class UriBuilderExt
    {
        private readonly NameValueCollection _collection;
        private readonly UriBuilder _builder;

        public UriBuilderExt(Uri uri)
        {
            _builder = new UriBuilder(uri);
            _collection = HttpUtility.ParseQueryString(string.Empty);
        }

        public UriBuilderExt AddParameter(string key, string value)
        {
            _collection.Add(key, value);
            return this;
        }

        public Uri Uri
        {
            get
            {
                _builder.Query = _collection.ToString();
                return _builder.Uri;
            }
        }
    }
}

@using BlazorWasm.Client.Services
@using BlazorServer.Models

namespace BlazorWasm.Client
{
    public class Program
    {
        public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);
            // ...

            builder.Services.AddScoped<IClientHotelRoomService, ClientHotelRoomService>();

            // ...
        }
    }
}

namespace BlazorWasm.WebApi.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class HotelRoomController : ControllerBase
    {
        // ...

        [HttpGet]
        public async Task<IActionResult> GetHotelRooms(DateTime? checkInDate, DateTime? checkOutDate)
        {
          // ...
        }

        [HttpGet("{roomId}")]
        public async Task<IActionResult> GetHotelRoom(int? roomId, DateTime? checkInDate, DateTime? checkOutDate)
        {
           // ...
        }
    }
}

namespace BlazorServer.Services
{
    public interface IHotelRoomService : IDisposable
    {
        Task<List<HotelRoomDTO>> GetAllHotelRoomsAsync(DateTime? checkInDate, DateTime? checkOutDate);
        Task<HotelRoomDTO> GetHotelRoomAsync(int roomId, DateTime? checkInDate, DateTime? checkOutDate);
        // ...
    }
}

{
    "BaseAPIUrl": "https://localhost:5001/"
}

namespace BlazorWasm.Client
{
    public class Program
    {
        public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);
            // ... 

            // builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
            builder.Services.AddScoped(sp => new HttpClient
            {
                BaseAddress = new Uri(builder.Configuration.GetValue<string>("BaseAPIUrl"))
            });

            // ... 
        }
    }
}

@page "/hotel/rooms"

@inject ILocalStorageService LocalStorage
@inject IJSRuntime JsRuntime
@inject IClientHotelRoomService HotelRoomService

<h3>HotelRooms</h3>

@code {
    HomeVM HomeModel = new HomeVM();
    IEnumerable<HotelRoomDTO> Rooms = new List<HotelRoomDTO>();

    protected override async Task OnInitializedAsync()
    {
        try
        {
            var model = await LocalStorage.GetItemAsync<HomeVM>(ConstantKeys.LocalInitialBooking);
            if (model is not null)
            {
                HomeModel = model;
            }
            else
            {
                HomeModel.NoOfNights = 1;
            }
            await LoadRooms();
        }
        catch (Exception e)
        {
            await JsRuntime.ToastrError(e.Message);
        }
    }

    private async Task LoadRooms()
    {
        Rooms = await HotelRoomService.GetHotelRoomsAsync(HomeModel.StartDate, HomeModel.EndDate);
    }
}

{
  "iisSettings": {
    "iisExpress": {
      "applicationUrl": "http://localhost:62930",
      "sslPort": 44314
    }
  }
}

{
    "BlazorWasm.Client": {
      "applicationUrl": "https://localhost:5002;http://localhost:5003",
    }  
}