| Check | Code | Description |
| Is Null | if(variable is null) return true; |
|
| Is Not Null | if(variable is { }) return false |
|
| Is Not Null | if(variable is object) return false |
|
| Is Null | if(variable == null) return true |
|
| Is Not Null | if(variable != null) return false |
|
This syntax supports static analysis such that later code will know whether variable is null or not.
Doesn’t produce a warning even when comparing against a non-nullable value type making the code to check pointless.
Requires C# 7.0 because it leverages type pattern matching.
public class LanguageRouteConstraint : IRouteConstraint
{
public bool Match(HttpContext httpContext, IRouter route, string routeKey, RouteValueDictionary values, RouteDirection routeDirection)
{
if (!values.ContainsKey("lang"))
{
return false;
}
var lang = values["lang"].ToString();
var result = lang == "fa" || lang == "en";
return result;
}
} public void ConfigureServices(IServiceCollection services)
{
services.AddLocalization(o => o.ResourcesPath = "Resources");
services.Configure<RouteOptions>(options =>
{
options.ConstraintMap.Add("lang", typeof(LanguageRouteConstraint));
});
services.AddMvc()
.SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
.AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix)
.AddDataAnnotationsLocalization(); public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseRequestLocalization(new RequestLocalizationOptions
{
DefaultRequestCulture = new RequestCulture(new CultureInfo("fa-IR")),
SupportedCultures = new[]
{
new CultureInfo("en-US"),
new CultureInfo("fa-IR"),
},
SupportedUICultures = new[]
{
new CultureInfo("en-US"),
new CultureInfo("fa-IR"),
},
RequestCultureProviders = new List<IRequestCultureProvider>()
{
new RouteDataRequestCultureProvider()
{
UIRouteDataStringKey = "lang",
RouteDataStringKey = "lang"
}
}
});
app.UseMvc(routes =>
{
routes.MapRoute(
name: "LocalizedAreas",
template: "{lang:lang}/{area:exists}/{controller=Home}/{action=Index}/{id?}");
routes.MapRoute(
name: "LocalizedDefault",
template: "{lang:lang}/{controller=Home}/{action=Index}/{id?}"
);
routes.MapRoute(
name: "default",
template: "{*catchall}",
defaults: new { controller = "Home", action = "RedirectToDefaultLanguage" });
}); PM> Install-Package Microsoft.AspNet.SignalR.JS
Signalr.exe ghp http://localhost/
$.connection
$.connection.chatHub
<!DOCTYPE>
<html>
<head>
<title></title>
<script src="Scripts/jquery-1.6.4.min.js" type="text/javascript"></script>
<script src="Scripts/jquery.signalR-1.0.1.min.js" type="text/javascript"></script>
<script src="http://localhost:1072/signalr/hubs" type="text/javascript"></script>
</head>
<body>
<div>
<input id="txtMsg" type="text" /><input id="send" type="button" value="send msg" />
<ul id="messages">
</ul>
</div>
<script type="text/javascript">
$(function () {
var chat;
$.connection.hub.logging = true; //اطلاعات بیشتری را در جاوا اسکریپت کنسول مرورگر لاگ میکند
chat = $.connection.chat; //این نام مستعار پیشتر توسط ویژگی نام هاب تنظیم شده است
chat.client.hello = function (message) {
//متدی که در اینجا تعریف شده دقیقا مطابق نام متد پویایی است که در هاب تعریف شده است
//به این ترتیب سرور میتواند کلاینت را فراخوانی کند
$("#messages").append("<li>" + message + "</li>");
};
$.connection.hub.start(/*{ transport: 'longPolling' }*/); // فاز اولیه ارتباط را آغاز میکند
$("#send").click(function () {
// Hub's `SendMessage` should be camel case here
chat.server.sendMessage($("#txtMsg").val());
});
});
</script>
</body>
</html><script src="http://localhost:1072/signalr/hubs" type="text/javascript"></script>
- webSockets - forverFrame - serverSentEvents - longPolling
$.connection.hub.url = 'http://localhost:1072/signalr'; //چون در یک پروژه دیگر قرار داریم
using System;
using System.Web;
using System.Web.Routing;
using Microsoft.AspNet.SignalR;
namespace SignalR02
{
public class Global : HttpApplication
{
protected void Application_Start(object sender, EventArgs e)
{
// Register the default hubs route: ~/signalr
RouteTable.Routes.MapHubs(new HubConfiguration
{
EnableCrossDomain = true
});
}
}
}SignalR: Auto detected cross domain url. jquery.signalR-1.0.1.min.js:10 SignalR: Negotiating with 'http://localhost:1072/signalr/negotiate'. jquery.signalR-1.0.1.min.js:10 SignalR: SignalR: Initializing long polling connection with server. jquery.signalR-1.0.1.min.js:10 SignalR: Attempting to connect to 'http://localhost:1072/signalr/connect?transport=longPolling&connectionToken…NRh72omzsPkKqhKw2&connectionData=%5B%7B%22name%22%3A%22chat%22%7D%5D&tid=3' using longPolling. jquery.signalR-1.0.1.min.js:10 SignalR: Longpolling connected jquery.signalR-1.0.1.min.js:10
<!DOCTYPE>
<html>
<head>
<title></title>
<script src="Scripts/jquery-1.6.4.min.js" type="text/javascript"></script>
<script src="Scripts/jquery.signalR-1.0.1.min.js" type="text/javascript"></script>
</head>
<body>
<div>
<input id="txtMsg" type="text" /><input id="send" type="button" value="send msg" />
<ul id="messages">
</ul>
</div>
<script type="text/javascript">
$(function () {
$.connection.hub.logging = true; //اطلاعات بیشتری را در جاوا اسکریپت کنسول مرورگر لاگ میکند
var connection = $.hubConnection();
connection.url = 'http://localhost:1072/signalr'; //چون در یک پروژه دیگر قرار داریم
var proxy = connection.createHubProxy('chat');
proxy.on('hello', function (message) {
//متدی که در اینجا تعریف شده دقیقا مطابق نام متد پویایی است که در هاب تعریف شده است
//به این ترتیب سرور میتواند کلاینت را فراخوانی کند
$("#messages").append("<li>" + message + "</li>");
});
$("#send").click(function () {
// Hub's `SendMessage` should be camel case here
proxy.invoke('sendMessage', $("#txtMsg").val());
});
connection.start();
});
</script>
</body>
</html>PM> Install-Package Microsoft.AspNet.SignalR.Client
using System;
using Microsoft.AspNet.SignalR.Client.Hubs;
namespace SignalR02.WinClient
{
class Program
{
static void Main(string[] args)
{
var hubConnection = new HubConnection(url: "http://localhost:1072/signalr");
var chat = hubConnection.CreateHubProxy(hubName: "chat");
chat.On<string>("hello", msg => {
Console.WriteLine(msg);
});
hubConnection.Start().Wait();
chat.Invoke<string>("sendMessage", "Hello!");
Console.WriteLine("Press a key to terminate the client...");
Console.Read();
}
}
}
namespace Project.Models
{
public class EmployeeCreateModel
{
[Required]
[Display(Name = "آدرس ایمیل")]
[EmailAddress(ErrorMessage = "لطفاً {0} معتبر وارد کنید.")]
[Remote("UserExistByEmailValidation",
HttpMethod = "POST",
ErrorMessage = "ایمیل وارد شده هم اکنون توسط یکی از کاربران مورد استفاده است.")]
public string Email { get; set; }
...
}
} namespace Project.Models
{
public class EmployeeEditModel
{
public int Id { get; set; }
[Required]
[Display(Name = "آدرس ایمیل")]
[EmailAddress(ErrorMessage = "لطفاً {0} معتبر وارد کنید.")]
[Remote("EmailExistForOtherUserValidation",
AdditionalFields = "Id",
HttpMethod = "POST",
ErrorMessage = "ایمیل وارد شده هم اکنون توسط یکی از کاربران مورد استفاده است.")]
public string Email { get; set; }
....
}
} namespace Project.Web.Controllers
{
[RoutePrefix("UserValidation")]
[Route("{Action}")]
[OutputCache(Location = OutputCacheLocation.None, NoStore = true)]
public partial class UserValidationController : Controller
{
readonly IUserService<User> _userService;
readonly IUnitOfWork _uow;
public UserValidationController(IUnitOfWork uow, IUserService<User> userService)
{
_userService = userService;
_uow = uow;
}
[HttpPost]
[Route("~/CheckEmail", Name = "UserExistByEmailValidation")]
public virtual JsonResult CheckEmail(string email)
{
return Json(!_userService.UserExistsByEmail(email));
}
[HttpPost]
[Route("~/CheckEmailForOtherUser", Name = "EmailExistForOtherUserValidation")]
public virtual JsonResult CheckEmailForOtherUser(string email, int id)
{
return Json(!_userService.EmailExistForOtherUser(email, id));
}
}
} 
@section Scripts {
@Scripts.Render("~/bundles/jqueryval")
} System.Security.Cryptography.CryptographicException: Object already exists
Resource interpreted as Image but transferred with MIME type text/html: "http://site:8080/Error/Index?aspxerrorpath=/Shared/CaptchaImage"
1. شاید یکی از آزاردهنده‌ترین مشکلات، برخورد با پیغام‌های خطا، هنگام عملیات migration باشد. یکی از ده‌ها نوع خطا، زمانی رخ میدهد که متد seed در حال اجراست. در این حالت هیچ نوع break-point ایی به کمک ما نخواهد آمد.
سوال ایجاست که آیا می‌توان این بخش را دیباگ نمود؟ بهترین راه حل، اجرای آپدیت از طریق متدها(یا اکشن ها) است.
فراخوانی migration بسیار ساده است. باید یک نمونه از کلاس Configuration را ساخته و در جایی از پروژه قرار دهیم و صد
البته مطمئن باشیم که migration فعال است.
var configuration = new Configuration(); var migrator = new DbMigrator(configuration); migrator.Update();
اگر بخواهید این تغییرات بر روی دیتابیسی با اسم و رسم انجام شود، از کد زیر بهره بگیرید:
var configuration = new Configuration();
configuration.TargetDatabase = new DbConnectionInfo(
"Server=MyServer;Database=MyDatabase;Trusted_Connection=True;",
"System.Data.SqlClient");
var migrator = new DbMigrator(configuration);
migrator.Update(); 2. خطای :
Duplicate type name within an assembly.
معمولا بخاطر وجود break-point این مشکل رخ میدهد. یا break-pointهای درون seed را حذف کنید یا جای آنها را تغییر دهید. [اینجا]
3. خطای :
Validation failed for one or more entities. See 'EntityValidationErrors' property for more details.
این مشکل میتواند دلایل مختلفی داشته
باشد. کد درون متد seed را داخلtry/catch قرا ر دهید و علت آن را بررسی کنید:
try
{
var user = new ApplicationUser { UserName = "Admin", Phone = "09120000000", Email = "m@gmail.com" };
usermanager.Create(user, "09120000000");
usermanager.AddToRole(user.Id, "admin");
}
catch (DbEntityValidationException dbEx)
{
foreach (var validationErrors in dbEx.EntityValidationErrors)
{
foreach (var validationError in validationErrors.ValidationErrors)
{
Trace.TraceInformation("Property: {0} Error: {1}", validationError.PropertyName, validationError.ErrorMessage);
}
}
} فراموش نکنید، seed را به کمک حالتی که در شماره 1 گفته شد اجرا کنید تا بتوانید از BreakPoint استفاده کنید.
4.خطای :
More than one context type was found in the assembly 'Ex1_CodeFirst'
این خطا وقتی ظاهر میشود که چندین Context برای
پروژه جاری داشته باشیم و ویژوال استودیو نتواند Context مورد نظر ما را تشخیص
دهد. بهتر است هنگام اجرای migration نام context مورد نظر را بنویسیم (مثلا MyConfiguration نام کانتکست شماست) :
Update-Database -ConfigurationTypeName MyConfiguration
There is already an object named 'UserProfile' in the database.
یعنی مدل شما پس از اینکه جدولی با همین نام (در این جا به عنوان مثال UserProfile) از پیش موجود بوده، تغییر کرده است؛ پس migration آپدیت شدنی نیست. ابتدا این دستور را می‌نویسیم (پیش از آنکه تغییراتمان را روی کلاس مربوط به جدول UserProfile اعمال کنیم):
Add-Migration Initial –IgnoreChanges
update-database –verbose
گاهی این مشکل زمانی پیش می‌آید که واقعا تغییری در جدول نامبرده انجام نداده‌ایم. در این حالت روش پله‌ای زیر را به کار می‌بریم:
There is already an object named 'UserProfile' in the database
Unable to update database to match the current model because there are pending changes and automatic migration is disabled. Either write the pending model changes to a code-based migration or enable automatic migration. Set DbMigrationsConfiguration.AutomaticMigrationsEnabled to true to enable automatic migration. You can use the Add-Migration command to write the pending model changes to a code-based migration.
Automatic migration was not applied because it would result in data loss.
AutomaticMigrationDataLossAllowed = true;
Introducing FOREIGN KEY constraint 'FK_dbo.ProductProductGroups_dbo.ProductGroups_ProductGroupId' on table 'ProductProductGroups' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could not create constraint or index. See previous errors.
- پاک کردن فولدر Migrations در پروژه
- پاک کردن جدولی به نام MigrationHistory_ در دیتابیس (ممکن است زیر مجموعه جدول‌های system باشد)
- اجرای دستور زیر کنسول پکیچ منیجر ویژوال استودیو :
Enable-Migrations -EnableAutomaticMigrations -Force
- اجرای دستور زیر :
Add-Migration Initial
PM> Install-Package Microsoft.AspNetCore.ResponseCompression
{
"dependencies": {
"Microsoft.AspNetCore.ResponseCompression": "1.0.0"
}
} public void ConfigureServices(IServiceCollection services)
{
services.AddResponseCompression(options =>
{
options.MimeTypes = Microsoft.AspNetCore.ResponseCompression.ResponseCompressionDefaults.MimeTypes;
});
} namespace Microsoft.AspNetCore.ResponseCompression
{
/// <summary>
/// Defaults for the ResponseCompressionMiddleware
/// </summary>
public class ResponseCompressionDefaults
{
/// <summary>
/// Default MIME types to compress responses for.
/// </summary>
// This list is not intended to be exhaustive, it's a baseline for the 90% case.
public static readonly IEnumerable<string> MimeTypes = new[]
{
// General
"text/plain",
// Static files
"text/css",
"application/javascript",
// MVC
"text/html",
"application/xml",
"text/xml",
"application/json",
"text/json",
};
}
} services.AddResponseCompression(options =>
{
options.MimeTypes = ResponseCompressionDefaults.MimeTypes.Concat(new[]
{
"image/svg+xml",
"application/font-woff2"
});
}); services.AddResponseCompression(options =>
{
//If no compression providers are specified then GZip is used by default.
//options.Providers.Add<GzipCompressionProvider>(); services.Configure<GzipCompressionProviderOptions>(options =>
{
options.Level = System.IO.Compression.CompressionLevel.Optimal;
}); options.EnableForHttps = true;
public void Configure(IApplicationBuilder app)
{
app.UseResponseCompression() // Adds the response compression to the request pipeline
.UseStaticFiles(); // Adds the static middleware to the request pipeline
} <staticContent> <clientCache httpExpires="Sun, 29 Mar 2020 00:00:00 GMT" cacheControlMode="UseExpires" /> </staticContent>
public void Configure(IApplicationBuilder app,
IHostingEnvironment env,
ILoggerFactory loggerFactory)
{
app.UseResponseCompression()
.UseStaticFiles(
new StaticFileOptions
{
OnPrepareResponse =
_ => _.Context.Response.Headers[HeaderNames.CacheControl] =
"public,max-age=604800" // A week in seconds
})
.UseMvc(routes => routes.MapRoute("default", "{controller=Home}/{action=Index}/{id?}"));
} PM> Install-Package Microsoft.AspNetCore.Rewrite
{
"dependencies": {
"Microsoft.AspNetCore.Rewrite": "1.0.0"
}
} public void Configure(IApplicationBuilder app)
{
app.UseRewriter(new RewriteOptions()
.AddRedirectToHttps()
.AddRewrite(@"app/(\d+)", "app?id=$1", skipRemainingRules: false) // Rewrite based on a Regular expression
//.AddRedirectToHttps(302, 5001) // Redirect to a different port and use HTTPS
.AddRedirect("(.*)/$", "$1") // remove trailing slash, Redirect using a regular expression
.AddRedirect(@"^section1/(.*)", "new/$1", (int)HttpStatusCode.Redirect)
.AddRedirect(@"^section2/(\\d+)/(.*)", "new/$1/$2", (int)HttpStatusCode.MovedPermanently)
.AddRewrite("^feed$", "/?format=rss", skipRemainingRules: false)); app.UseRewriter(new RewriteOptions() .AddIISUrlRewrite(env.ContentRootFileProvider, "web.config") .AddApacheModRewrite(env.ContentRootFileProvider, ".htaccess"));
public class RedirectWwwRule : Microsoft.AspNetCore.Rewrite.IRule
{
public int StatusCode { get; } = (int)HttpStatusCode.MovedPermanently;
public bool ExcludeLocalhost { get; set; } = true;
public void ApplyRule(RewriteContext context)
{
var request = context.HttpContext.Request;
var host = request.Host;
if (host.Host.StartsWith("www", StringComparison.OrdinalIgnoreCase))
{
context.Result = RuleResult.ContinueRules;
return;
}
if (ExcludeLocalhost && string.Equals(host.Host, "localhost", StringComparison.OrdinalIgnoreCase))
{
context.Result = RuleResult.ContinueRules;
return;
}
string newPath = request.Scheme + "://www." + host.Value + request.PathBase + request.Path + request.QueryString;
var response = context.HttpContext.Response;
response.StatusCode = StatusCode;
response.Headers[HeaderNames.Location] = newPath;
context.Result = RuleResult.EndResponse; // Do not continue processing the request
}
} app.UseRewriter(new RewriteOptions().Add(new RedirectWwwRule()));
var options = new RewriteOptions().Add(app.ApplicationServices.GetService<RedirectWwwRule>());
<add name="TestContext"
connectionString="Data Source=localhost;Initial Catalog=Test;User ID=sa;Password=123;MultipleActiveResultSets=True;"
providerName="System.Data.EntityClient" /> <add name="TestContext"
connectionString="Data Source=localhost;Initial Catalog=Test;Integrated Security=True"
providerName="System.Data.EntityClient" /> @page "/" <h1>Hello, world!</h1>
@page "/bindprop"
<li class="nav-item px-3">
<NavLink class="nav-link" href="bindprop">
<span class="oi oi-list-rich" aria-hidden="true"></span> Bind Properties
</NavLink>
</li> 
@page "/demoHotel"
<h3>Hotel Rooms</h3>
<div class="border p-2 mt-2" style="background-color:azure">
<h2 class="text-info">Rooms List</h2>
<div class="row container">
@foreach (var room in Rooms)
{
<div class="bg-light border p-2 col-5 ml-2">
<h4 class="text-secondary">Room - @room.Id</h4>
@room.Name<br />
@room.Price.ToString("c")<br />
<input type="checkbox" @bind-value="room.IsActive" checked="@(room.IsActive?"checked":null)" /> Is Active<br />
<span>This room is @(room.IsActive?"Active": "InActive")</span>
@if (room.IsActive)
{
@foreach (var roomProp in room.RoomProps)
{
<p>@roomProp.Name - @roomProp.Value</p>
}
}
<input type="button" class="btn btn-danger" value="Delete" />
<input type="button" class="btn btn-success" value="Edit" />
</div>
}
</div>
</div> <li class="nav-item px-3">
<NavLink class="nav-link" href="demoHotel">
<span class="oi oi-list-rich" aria-hidden="true"></span> Demo Hotel
</NavLink>
</li> 
<input type="button" class="btn btn-danger" value="Delete" /> <input type="button" class="btn btn-success" value="Edit" />
<BlazorServerSample.Pages.LearnBlazor.LearnBlazorComponents.EditDeleteButton></BlazorServerSample.Pages.LearnBlazor.LearnBlazorComponents.EditDeleteButton>
@using BlazorServerSample.Pages.LearnBlazor.LearnBlazorComponents
<EditDeleteButton></EditDeleteButton>
@if (IsAdmin)
{
<input type="button" class="btn btn-danger" value="Delete" />
<input type="button" class="btn btn-success" value="Edit" />
}
@code
{
[Parameter]
public bool IsAdmin { get; set; }
} <EditDeleteButton IsAdmin="true"></EditDeleteButton>
<div class="bg-light border p-2 col-5 offset-1">
<h4 class="text-secondary">Room - @Room.Id</h4>
@Room.Name<br />
@Room.Price.ToString("c")<br />
<input type="checkbox" @bind-value="Room.IsActive" checked="@(Room.IsActive?"checked":null)" /> Is Active<br />
<span>This room is @(Room.IsActive?"Active": "InActive")</span>
@if (Room.IsActive)
{
@foreach (var roomProp in Room.RoomProps)
{
<p>@roomProp.Name - @roomProp.Value</p>
}
}
<EditDeleteButton IsAdmin="true"></EditDeleteButton>
</div>
@code
{
[Parameter]
public BlazorRoom Room { get; set; }
} <div class="row container">
@foreach (var room in Rooms)
{
<IndividualRoom Room="@room"></IndividualRoom>
}
</div> 
namespace BlazorServerSample.Models
{
public class BlazorAmenity
{
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
}
} @code{
List<BlazorAmenity> AmenitiesList = new List<BlazorAmenity>();
// ...
protected override void OnInitialized()
{
base.OnInitialized();
// ...
AmenitiesList.Add(new BlazorAmenity
{
Id = 111,
Name = "Gym",
Description = "24x7 gym room is available."
});
AmenitiesList.Add(new BlazorAmenity
{
Id = 222,
Name = "Swimming Pool",
Description = "Pool room is open from 6am to 10pm."
});
AmenitiesList.Add(new BlazorAmenity
{
Id = 333,
Name = "Free Brakfast",
Description = "Enjoy free breakfast at out hotel."
});
}
} <div class="bg-light border p-2 col-5 offset-1 mt-2">
<h4 class="text-secondary">Amenity - @Amenity.Id</h4>
@Amenity.Name<br />
@Amenity.Description<br />
</div>
@code
{
[Parameter]
public BlazorAmenity Amenity { get; set; }
} <div class="col-12 mt-4">
<h4 class="text-info">Hotel Amenities</h4>
</div>
@foreach (var amenity in AmenitiesList)
{
<IndividualAmenity Amenity="@amenity"></IndividualAmenity>
} 
using System;
using Microsoft.AspNetCore.Hosting;
namespace aspnetcoreapp
{
public class Program
{
public static void Main(string[] args)
{
var host = new WebHostBuilder()
.UseKestrel()
.UseStartup<Startup>()
.Build();
host.Run();
}
}
} // This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices (IServiceCollection services)
{
// Add framework services.
services.AddDbContext<ApplicationDbContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
services.AddIdentity<ApplicationUser, IdentityRole>()
.AddEntityFrameworkStores<ApplicationDbContext>()
.AddDefaultTokenProviders();
services.AddMvc();
// Add application services.
services.AddTransient<IEmailSender, AuthMessageSender>();
services.AddTransient<ISmsSender, AuthMessageSender>();
}