ReactDOM.render(<Counter />, document.getElementById("root"));

import Counters from "./components/counters";

ReactDOM.render(<Counters />, document.getElementById("root"));

import React, { Component } from "react";

import Counter from "./counter";

class Counters extends Component {
  state = {};

  render() {
    return (
      <div>
        <Counter />
        <Counter />
        <Counter />
        <Counter />
      </div>
    );
  }
}

export default Counters;

import React, { Component } from "react";
import Counter from "./counter";

class Counters extends Component {
  state = {
    counters: [
      { id: 1, value: 0 },
      { id: 2, value: 0 },
      { id: 3, value: 0 },
      { id: 4, value: 0 }
    ]
  };

  render() {
    return (
      <div>
        {this.state.counters.map(counter => (
          <Counter key={counter.id} />
        ))}
      </div>
    );
  }
}

export default Counters;

  render() {
    return (
      <div>
        {this.state.counters.map(counter => (
          <Counter key={counter.id} value={counter.value} selected={true} />
        ))}
      </div>
    );

class Counter extends Component {
  state = {
    count: 0
  };

  render() {
    console.log("props", this.props);
    //...

class Counter extends Component {
  state = {
    count: this.props.value
  };

  render() {
    return (
      <div>
        {this.state.counters.map(counter => (
          <Counter key={counter.id} value={counter.value} selected={true}>
            <h4>‍Counter #{counter.id}</h4>
          </Counter>
        ))}
      </div>
    );
  }

class Counter extends Component {
  state = {
    count: this.props.value
  };

  handleDelete = () => {
    console.log("handleDelete called.");
  };

<Counter
     key={counter.id}
     value={counter.value}
     selected={true}
     onDelete={this.handleDelete}
/>

<button
  onClick={this.props.onDelete}
  className="btn btn-danger btn-sm m-2"
>
  Delete
</button>

onClick={() => this.props.onDelete(this.props.id)}

<Counter
  key={counter.id}
  value={counter.value}
  selected={true}
  onDelete={this.handleDelete}
  id={counter.id}
/>

  handleDelete = counterId => {
    console.log("handleDelete called.", counterId);
    const counters = this.state.counters.filter(
      counter => counter.id !== counterId
    );
    this.setState({ counters }); // = this.setState({ counters: counters });
  };

<Counter
  key={counter.id}
  counter={counter}
  onDelete={this.handleDelete}
/>

using (var db = new BloggingContext())
{
   var blog = new Blog { Url = "http://sample.com" };
   db.Blogs.Add(blog);
   db.SaveChanges();
}

using (var db = new BloggingContext())
{
  var blog = db.Blogs.First();
  blog.Url = "http://sample.com/blog";
  db.SaveChanges();
}

using (var db = new BloggingContext())
{
  var blog = db.Blogs.First();
  db.Blogs.Remove(blog);
  db.SaveChanges();
}

using (var context = new BloggingContext())
{
   var blog = context.Blogs
      .Select(b =>
            new
            {
               Blog = b,
               Posts = b.Posts.Count()
            });
 }

using (var context = new BloggingContext())
{
   var blog = context.Blogs
            .Select(b =>
                 new
                 {
                   Id = b.BlogId,
                   Url = b.Url
                 });
 }

using (var context = new BloggingContext())
{
  var blogs = context.Blogs.AsNoTracking().ToList();
}

using (var context = new BloggingContext())
{
    context.ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;

using (var context = new BloggingContext())
{
  var blog = context.Blogs.First();
  var post = new Post { Title = "Intro to EF Core" };

  blog.Posts.Add(post);
  context.SaveChanges();
}

using (var context = new BloggingContext())
{
  var blog = new Blog { Url = "http://blogs.msdn.com/visualstudio" };
  var post = context.Posts.First();

  blog.Posts.Add(post);
  context.SaveChanges();
}

 var blog = new Blog { Id = 2, Url = "https://www.dntips.ir" };
 context.Blog.Attach(blog);
 context.SaveChanges();

 var blog = new Blog { Id = 2, Url = "https://www.dntips.ir" };
 context.Entry(blog).State = EntityState.Modified ;
 context.SaveChanges();

 var blog = new Blog { Id = 2, Url = "https://www.dntips.ir" };
 context.Update(blog);
 context.SaveChanges();

 context.ChangeTracker.TrackGraph(blog, e => e.Entry.State = EntityState.Added);

public class BaseEntity
{
   public int Id { set; get; }
   public DateTime? DateAdded { set; get; }
   public DateTime? DateUpdated { set; get; }
}

public class Person : BaseEntity
{
   public string FirstName { get; set; }
   public string LastName { get; set; }
}

    public class ApplicationDbContext : DbContext
    {
        // same as before 

        public override int SaveChanges()
        {
            this.ChangeTracker.DetectChanges();

            var modifiedEntries = this.ChangeTracker
                                      .Entries<BaseEntity>()
                                      .Where(x => x.State == EntityState.Modified);
            foreach (var modifiedEntry in modifiedEntries)
            {
                modifiedEntry.Entity.DateUpdated = DateTime.UtcNow;
            }
 
            var addedEntries = this.ChangeTracker
                                      .Entries<BaseEntity>()
                                      .Where(x => x.State == EntityState.Added);
            foreach (var addedEntry in addedEntries)
            {
                addedEntry.Entity.DateAdded = DateTime.UtcNow;
            }
 
            return base.SaveChanges();
        }
    }

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
  modelBuilder.Entity<Blog>().Property<DateTime>("DateAdded");

 var blogs = context.Blogs.OrderBy(b => EF.Property<DateTime>(b, "DateAdded"));

 context.Entry(myBlog).Property("DateAdded").CurrentValue = DateTime.Now;

foreach (var addedEntry in addedEntries)
{
  addedEntry.Property("DateAdded").CurrentValue = DateTime.UtcNow;
}

if(person == null) { }

if(person is null) { }

public class Person
{
  public static bool operator ==(Person x, Person y)
  {
    return false;
  }
  public static bool operator !=(Person x, Person y)
  {
    return !(x == y);
  }
  public override bool Equals(object obj)
  {
    return base.Equals(obj);
  }
}

Person person = null;
Console.WriteLine("Is Person null?");
Console.WriteLine($"== says: {person == null}");
Console.WriteLine($"is says: {person is null}");

Is Person null?
== says: True
is says: True

Is Person null?
== says: False
is says: True

public static bool operator ==(Person x, Person y)
{
   return false;
}

@page "/registration"

@inject IClientAuthenticationService AuthenticationService
@inject NavigationManager NavigationManager


<EditForm Model="UserForRegistration" OnValidSubmit="RegisterUser" class="pt-4">
    <DataAnnotationsValidator />
    <div class="py-4">
        <div class=" row form-group ">
            <div class="col-6 offset-3 ">
                <div class="card border">
                    <div class="card-body px-lg-5 pt-4">
                        <h3 class="col-12 text-success text-center py-2">
                            <strong>Sign Up</strong>
                        </h3>
                        @if (ShowRegistrationErrors)
                        {
                            <div>
                                @foreach (var error in Errors)
                                {
                                    <p class="text-danger text-center">@error</p>
                                }
                            </div>
                        }
                        <hr style="background-color:aliceblue" />
                        <div class="py-2">
                            <InputText @bind-Value="UserForRegistration.Name" class="form-control" placeholder="Name..." />
                            <ValidationMessage For="(()=>UserForRegistration.Name)" />
                        </div>
                        <div class="py-2">
                            <InputText @bind-Value="UserForRegistration.Email" class="form-control" placeholder="Email..." />
                            <ValidationMessage For="(()=>UserForRegistration.Email)" />
                        </div>
                        <div class="py-2 input-group">
                            <div class="input-group-prepend">
                                <span class="input-group-text"> +1</span>
                            </div>
                            <InputText @bind-Value="UserForRegistration.PhoneNo" class="form-control" placeholder="Phone number..." />
                            <ValidationMessage For="(()=>UserForRegistration.PhoneNo)" />
                        </div>
                        <div class="form-row py-2">
                            <div class="col">
                                <InputText @bind-Value="UserForRegistration.Password" type="password" id="password" placeholder="Password..." class="form-control" />
                                <ValidationMessage For="(()=>UserForRegistration.Password)" />
                            </div>
                            <div class="col">
                                <InputText @bind-Value="UserForRegistration.ConfirmPassword" type="password" id="confirm" class="form-control" placeholder="Confirm Password..." />
                                <ValidationMessage For="(()=>UserForRegistration.ConfirmPassword)" />
                            </div>
                        </div>
                        <hr style="background-color:aliceblue" />
                        <div class="py-2">
                            @if (IsProcessing)
                            {
                                <button type="submit" class="btn btn-success btn-block disabled"><i class="fas fa-sign-in-alt"></i> Please Wait...</button>
                            }
                            else
                            {
                                <button type="submit" class="btn btn-success btn-block"><i class="fas fa-sign-in-alt"></i> Register</button>
                            }
                        </div>
                    </div>
                </div>
            </div>
        </div>
    </div>
</EditForm>

@code{
    UserRequestDTO UserForRegistration = new UserRequestDTO();
    bool IsProcessing;
    bool ShowRegistrationErrors;
    IEnumerable<string> Errors;

    private async Task RegisterUser()
    {
        ShowRegistrationErrors = false;
        IsProcessing = true;
        var result = await AuthenticationService.RegisterUserAsync(UserForRegistration);
        if (result.IsRegistrationSuccessful)
        {
            IsProcessing = false;
            NavigationManager.NavigateTo("/login");
        }
        else
        {
            IsProcessing = false;
            Errors = result.Errors;
            ShowRegistrationErrors = true;
        }
    }
}

@page "/login"

@inject IClientAuthenticationService AuthenticationService
@inject NavigationManager NavigationManager

<div id="logreg-forms">
    <h1 class="h3 mb-3 pt-3 font-weight-normal text-primary" style="text-align:center;">Sign In</h1>
    <EditForm Model="UserForAuthentication" OnValidSubmit="LoginUser">
        <DataAnnotationsValidator />
        @if (ShowAuthenticationErrors)
        {
            <p class="text-center text-danger">@Errors</p>
        }
        <InputText @bind-Value="UserForAuthentication.UserName" id="email" placeholder="Email..." class="form-control mb-2" />
        <ValidationMessage For="(()=>UserForAuthentication.UserName)"></ValidationMessage>
        <InputText @bind-Value="UserForAuthentication.Password" type="password" placeholder="Password..." id="password" class="form-control mb-2" />
        <ValidationMessage For="(()=>UserForAuthentication.Password)"></ValidationMessage>
        @if (IsProcessing)
        {
            <button type="submit" class="btn btn-success btn-block disabled"><i class="fas fa-sign-in-alt"></i> Please Wait...</button>
        }
        else
        {
            <button type="submit" class="btn btn-success btn-block"><i class="fas fa-sign-in-alt"></i> Sign in</button>
        }
        <a href="/registration" class="btn btn-primary text-white mt-3"><i class="fas fa-user-plus"></i> Register as a new user</a>
    </EditForm>
</div>
@code
{
    AuthenticationDTO UserForAuthentication = new AuthenticationDTO();
    bool IsProcessing = false;
    bool ShowAuthenticationErrors;
    string Errors;
    string ReturnUrl;

    private async Task LoginUser()
    {
        ShowAuthenticationErrors = false;
        IsProcessing = true;
        var result = await AuthenticationService.LoginAsync(UserForAuthentication);
        if (result.IsAuthSuccessful)
        {
            IsProcessing = false;
            var absoluteUri = new Uri(NavigationManager.Uri);
            var queryParam = HttpUtility.ParseQueryString(absoluteUri.Query);
            ReturnUrl = queryParam["returnUrl"];
            if (string.IsNullOrEmpty(ReturnUrl))
            {
                NavigationManager.NavigateTo("/");
            }
            else
            {
                NavigationManager.NavigateTo("/" + ReturnUrl);
            }
        }
        else
        {
            IsProcessing = false;
            Errors = result.ErrorMessage;
            ShowAuthenticationErrors = true;
        }
    }
}

<AuthorizeView>
    <Authorized>
        <li class="nav-item p-0">
          <NavLink class="nav-link" href="#">
             <span class="p-2">
                Hello, @context.User.Identity.Name!
             </span>
          </NavLink>
        </li>
        <li class="nav-item p-0">
          <NavLink class="nav-link" href="logout">
             <span class="p-2">
                Logout
             </span>
          </NavLink>
        </li>
    </Authorized>
    <NotAuthorized>
        <li class="nav-item p-0">
          <NavLink class="nav-link" href="registration">
            <span class="p-2">
               Register
            </span>
          </NavLink>
        </li>
        <li class="nav-item p-0">
          <NavLink class="nav-link" href="login">
            <span class="p-2">
              Login
            </span>
          </NavLink>
        </li>
    </NotAuthorized>
</AuthorizeView>

@page "/logout"

@inject IClientAuthenticationService AuthenticationService
@inject NavigationManager NavigationManager

@code
{
    protected async override Task OnInitializedAsync()
    {
        await AuthenticationService.LogoutAsync();
        NavigationManager.NavigateTo("/");
    }
}

namespace BlazorWasm.Client.Services
{
    public class AuthStateProvider : AuthenticationStateProvider
    {
        // ...

        public void NotifyUserLoggedIn(string token)
        {
            var authenticatedUser = new ClaimsPrincipal(
                                        new ClaimsIdentity(JwtParser.ParseClaimsFromJwt(token), "jwtAuthType")
                                    );
            var authState = Task.FromResult(new AuthenticationState(authenticatedUser));
            base.NotifyAuthenticationStateChanged(authState);
        }

        public void NotifyUserLogout()
        {
            var authState = Task.FromResult(new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity())));
            base.NotifyAuthenticationStateChanged(authState);
        }
    }
}

namespace BlazorWasm.Client.Services
{
    public class ClientAuthenticationService : IClientAuthenticationService
    {
        private readonly HttpClient _client;
        private readonly ILocalStorageService _localStorage;
        private readonly AuthenticationStateProvider _authStateProvider;

        public ClientAuthenticationService(
            HttpClient client,
            ILocalStorageService localStorage,
            AuthenticationStateProvider authStateProvider)
        {
            _client = client;
            _localStorage = localStorage;
            _authStateProvider = authStateProvider;
        }

        public async Task<AuthenticationResponseDTO> LoginAsync(AuthenticationDTO userFromAuthentication)
        {
            // ...
            if (response.IsSuccessStatusCode)
            {
                //...
                ((AuthStateProvider)_authStateProvider).NotifyUserLoggedIn(result.Token);

                return new AuthenticationResponseDTO { IsAuthSuccessful = true };
            }
            //...
        }

        public async Task LogoutAsync()
        {
            //...
            ((AuthStateProvider)_authStateProvider).NotifyUserLogout();
        }
    }
}

@attribute [Authorize(Roles = ‍ConstantRoles.Customer)]

@using Microsoft.AspNetCore.Authorization

@page "/hotel-room-details/{Id:int}"

// ...

@code {
     // ...

    protected override async Task OnInitializedAsync()
    {
        try
        {
            HotelBooking.OrderDetails = new RoomOrderDetailsDTO();
            if (Id != null)
            {
                // ...

                if (await LocalStorage.GetItemAsync<UserDTO>(ConstantKeys.LocalUserDetails) != null)
                {
                    var userInfo = await LocalStorage.GetItemAsync<UserDTO>(ConstantKeys.LocalUserDetails);
                    HotelBooking.OrderDetails.UserId = userInfo.Id;
                    HotelBooking.OrderDetails.Name = userInfo.Name;
                    HotelBooking.OrderDetails.Email = userInfo.Email;
                    HotelBooking.OrderDetails.Phone = userInfo.PhoneNo;
                }
            }
        }
        catch (Exception e)
        {
            await JsRuntime.ToastrError(e.Message);
        }
    }

public async Task<RoomOrderDetailsDTO> SaveRoomOrderDetailsAsync(RoomOrderDetailsDTO details)
{
   // details.UserId = "unknown user!";

var integerArray = new int[3];
var lastItem = integerArray[integerArray.Length - 1];

var integerList = integerArray.ToList();
integerList.Last();

var secondToLast = integerArray[integerArray.Length - 2];

var lastItem = integerArray[^1];

var words = new string[]
{
                // index from start    index from end
    "The",      // 0                   ^9
    "quick",    // 1                   ^8
    "brown",    // 2                   ^7
    "fox",      // 3                   ^6
    "jumped",   // 4                   ^5
    "over",     // 5                   ^4
    "the",      // 6                   ^3
    "lazy",     // 7                   ^2
    "dog"       // 8                   ^1
};              // 9 (or words.Length) ^0

Console.WriteLine($"The last word is {words[words.Length - 1]}");

var index = new Index(value: 1, fromEnd: true);
Index indexStruct = ^1;
var indexShortHand = ^1;

int[] a = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
Console.WriteLine(a[a.Length – 2]); // will write 8 on console.
Console.WriteLine(a[^2]); // will write 8 on console.

Index i5 = 5;
Console.WriteLine(a[i5]);        //will write 5 on console.

Index i2fromEnd = ^2;
Console.WriteLine(a[i2fromEnd]); // will write 8 on console.

var numbers = Enumerable.Range(1, 10).ToArray();

var (start, end) = (1, 7); 
var length = end - start; 

// Using LINQ 
var subset1 = numbers.Skip(start).Take(length);
 
// Or using Array.Copy 
var subset2 = new int[length];
Array.Copy(numbers, start, subset2, 0, length);

var myArray = new string[] { "Item1", "Item2", "Item3", "Item4", "Item5" };

 var fromIndexToX = myArray[1..3]; // = [Item2, Item3]

var fromIndexToXFromTheEnd = myArray[1..^1]; // = [ "Item2", "Item3", "Item4" ]

var fromAnIndexToTheEnd = myArray[1..]; // = [ "Item2", "Item3", "Item4", "Item5" ]

 var fromTheStartToAnIndex = myArray[..3]; // = [ "Item1", "Item2", "Item3" ]

 var entireRange = myArray[..]; // = [ "Item1", "Item2", "Item3", "Item4", "Item5" ]

var myArray = new string[] { "Item1", "Item2", "Item3", "Item4", "Item5" };
for (int i = 1; i <= 3; i++)
{
  Console.WriteLine(myArray[i]);
}

foreach (var item in myArray[1..4]) // = [ "Item2", "Item3", "Item4" ]
{
  Console.WriteLine(item);
}

using System;
using System.Linq;

namespace ConsoleApp
{
    class Program
    {
        private static readonly int[] _numbers = Enumerable.Range(1, 10).ToArray();

        static void Main()
        {
            var skip2CharactersAndTake2Characters = _numbers[2..4]; // صرفنظر کردن از دو عنصر اول و سپس انتخاب دو عنصر
            var skipFirstAndLastCharacter = _numbers[1..^1]; // صرفنظر کردن از دو عنصر اول و آخر
            var last3Characters = _numbers[^3..]; // انتخاب بازه‌ای شامل سه عنصر آخر
            var first4Characters = _numbers[0..4]; // دریافت بازه‌ای از 4 عنصر اول
            var rangeStartFrom2 = _numbers[2..]; // دریافت بازه‌ای شروع شده از المان دوم تا آخر
            var skipLast3Characters = _numbers[..^3]; // صرفنظر کردن از سه المان آخر
            var rangeAll = _numbers[..]; // انتخاب کل بازه
        }
    }
}

var range = new Range(1, 4);
Range rangeStruct = 1..4;
var rangeShortHand = 1..4;

using System;
using System.Linq;

namespace ConsoleApp
{
    class Program
    {
        private static readonly int[] _numbers = Enumerable.Range(1, 10).ToArray();
        static void Print(Range range) => Console.WriteLine($"{range} => {string.Join(", ", _numbers[range])}");

        static void Main()
        {
            Print(1..3); // 1..3 => 2, 3
            Print(..3);      // 0..3 => 1, 2, 3
            Print(3..);      // 3..^0 => 4, 5, 6, 7, 8, 9, 10
            Print(1..^1);    // 1..^1 => 2, 3, 4, 5, 6, 7, 8, 9
            Print(^2..^1);   // ^2..^1 => 9
        }
    }
}

Console.WriteLine("123456789"[1..4]); // Would output 234

var helloWorldStr = "Hello, World!";

var hello = helloWorldStr[..5];
Console.WriteLine(hello); // Output: Hello

var world = helloWorldStr[7..];
Console.WriteLine(world); // Output: World!

var world2 = helloWorldStr[^6..]; // Take the last 6 characters
Console.WriteLine(world); // Output: World!

var arr = (new[] { 1, 4, 8, 11, 19, 31 }).AsSpan();
var range = arr[2..5];

ref int elt1 = ref range[1];
elt1 = -1;

int copiedElement = range[2];
copiedElement = -2;

Console.WriteLine($"range[1]: {range[1]}, range[2]: {range[2]}"); // output: range[1]: -1, range[2]: 19
Console.WriteLine($"arr[3]: {arr[3]}, arr[4]: {arr[4]}"); // output: arr[3]: -1, arr[4]: 19

<a id="@item.Id" class="detail" data-toggle="modal" data-target=".bs-example-modal-lg" href="#">جزئیات</a>

<div class="modal fade bs-example-modal-lg" tabindex="-1" role="dialog" aria-labelledby="myLargeModalLabel" aria-hidden="true">
    <div class="modal-dialog">
        <div class="modal-content">
            // نتیجه اطلاعات
        </div><!-- /.modal-content -->
    </div><!-- /.modal-dialog -->
</div><!-- /.modal -->

<script type="text/javascript">
        $(function() {
            $('.detail').click(function () {
                var selectedId = $(this).attr('id');
                // نتیجه اکشن متد زیر یک پارشال ویو است
                $.post('@Url.Action("GetRequestById")' + "/" + selectedId, function (data) {
                    $('.modal-content').html(data);
                });
            });
        });
</script>