public class AccountType : ObjectGraphType<Account>
{
    public AccountType()
    {
        Field(x => x.Id, type: typeof(IdGraphType)).Description("Id property from the account object.");
        Field(x => x.Description).Description("Description property from the account object.");
        Field(x => x.OwnerId, type: typeof(IdGraphType)).Description("OwnerId property from the account object.");
    }
}

public interface IAccountRepository
{
    IEnumerable<Account> GetAllAccountsPerOwner(Guid ownerId);
}

public class AccountRepository : IAccountRepository
{
    private readonly ApplicationContext _context;
 
    public AccountRepository(ApplicationContext context)
    {
       _context = context;
    }
 
    public IEnumerable<Account> GetAllAccountsPerOwner(Guid ownerId) => _context.Accounts
        .Where(a => a.OwnerId.Equals(ownerId))
        .ToList();
}

public class OwnerType : ObjectGraphType<Owner>
{
    public OwnerType(IAccountRepository repository)
    {
        Field(x => x.Id, type: typeof(IdGraphType)).Description("Id property from the owner object.");
        Field(x => x.Name).Description("Name property from the owner object.");
        Field(x => x.Address).Description("Address property from the owner object.");
        Field<ListGraphType<AccountType>>(
            "accounts",
            resolve: context => repository.GetAllAccountsPerOwner(context.Source.Id)
        );
    }
}

https://localhost:5001/ui/playground

{
  owners{
    id,
    name,
    address,
    accounts{
      id,
      description,
      ownerId
    }
  }
}

public class AccountTypeEnumType : EnumerationGraphType<TypeOfAccount>
{
    public AccountTypeEnumType()
    {
        Name = "Type";
        Description = "Enumeration for the account type object.";
    }
}

public class AccountType : ObjectGraphType<Account>
{
    public AccountType()
    {
        ...
        Field<AccountTypeEnumType>("Type", "Enumeration for the account type object.");
    }
}

{
  owners{
    id,
    name,
    address,
    accounts{
      id,
      description,
      type,
      ownerId
    }
  }
}

public interface IOwnerRepository
{
    ...
    Owner GetById(Guid id);
}

public class OwnerRepository : IOwnerRepository
{
    ...
    Owner GetById(Guid id) => _context.Owners.SingleOrDefault(o => o.Id.Equals(id));
}

public class AppQuery : ObjectGraphType
{
    public AppQuery(IOwnerRepository repository)
    {
        ...

        Field<OwnerType>(
            "owner",
            arguments: new QueryArguments(new QueryArgument<NonNullGraphType<IdGraphType>> { Name = "ownerId" }),
            resolve: context =>
            {
                var id = context.GetArgument<Guid>("ownerId");
                return repository.GetById(id);
            }
        );
    }
}

Field<OwnerType>(
    "owner",
    arguments: new QueryArguments(new QueryArgument<NonNullGraphType<IdGraphType>> { Name = "ownerId" }),
    resolve: context =>
    {
        Guid id;
        if (!Guid.TryParse(context.GetArgument<string>("ownerId"), out id))
        {
            context.Errors.Add(new ExecutionError("Wrong value for guid"));
            return null;
        }
 
         return repository.GetById(id);
     }
);

{
  first:owners{
    ownerId:id,
    ownerName:name,
    ownerAddress:address,
    ownerAccounts:accounts
    {
      accountId:id,
      accountDescription:description,
      accountType:type
    }
  },
  second:owners{
    ownerId:id,
    ownerName:name,
    ownerAddress:address,
    ownerAccounts:accounts
    {
      accountId:id,
      accountDescription:description,
      accountType:type
    }
  }
}

class Visitor {
    visit(item){}
}

class BookVisitor extends Visitor {
    visit(book) {
        var cost=0; 
        if(book.getPrice() > 50) 
        { 
            cost = book.getPrice()*0.50 
        } 
        else{
            cost = book.getPrice()
        }     
        console.log("Book name: "+ book.getName() + "\n" + "ID: " + book.getID() + "\n" + "cost: "+ cost); 
        return cost; 
    }
}

class Book{
    constructor(id,name,price){
        this.id = id
        this.name = name
        this.price = price
    }
    getPrice(){
        return this.price
    }
    getName(){
        return this.name
    }
    getID(){
        return this.id
    }
    accept(visitor){
        return visitor.visit(this)
    }
}

var visitor = new BookVisitor()
var book1 = new Book("#1234","lordOftheRings",80)
book1.accept(visitor)

class Book{
    constructor(id,name,price){
        this.id = id
        this.name = name
        this.price = price
    }
    //code...
}

getPrice(){
    return this.price
}

getName(){
    return this.name
}

getID(){
    return this.id
}

accept(visitor){
    return visitor.visit(this)
}

1. زمانیکه نیاز است عملیاتی مشابه، بر روی شیء‌های متفاوتی از یک data structure  انجام شود. 
   
2. زمانیکه نیاز است عملیاتی خاص، بر روی شیء‌های متفاوتی از data structure انجام شود. 
   
3. زمانیکه می‌خواهید توسعه پذیری را برای کتابخانه‌ها (libraries) یا فریم ورک‌ها (frameworks) اضافه کنید.
   

var claimsIdentity = this.User.Identity as ClaimsIdentity ;

"ApplicationName": "Dependency Injection Demo",
"GreetingMessage": "Welcome to Dependency Injection Demo",
"AllowedHosts": "*",

"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
},

namespace AspNetCoreDependencyInjection.Configs
{
    public class AppConfig
    {
        public string ApplicationName { get; set; }
        public string GreetingMessage { get; set; }
        public string AllowedHosts { get; set; }
    }
}

public IWebHostEnvironment Environment { get; }
public IConfiguration Configuration { get; }
public IServiceCollection Services { get; set; }

public Startup(IWebHostEnvironment environment)
{
var builder = new ConfigurationBuilder()
        .SetBasePath(environment.ContentRootPath)
        .AddJsonFile("appsettings.json", optional: true)
        .AddEnvironmentVariables();
        this.Environment = environment;
        this.Configuration = builder.Build();
}

var appSettingsFile = environment.IsProduction() ? "appsettings.json" : "appsettings_dev.json";
var builder = new ConfigurationBuilder()
.SetBasePath(environment.ContentRootPath)
                .AddJsonFile( appSettingsFile , optional: true)
                .AddEnvironmentVariables();

services.AddSingleton(services => new AppConfig { 
    ApplicationName = this.Configuration["ApplicationName"],
    GreetingMessage = this.Configuration["GreetingMessage"],
    AllowedHosts = this.Configuration["AllowedHosts"]
});

public class AppSettingsController : Controller
{
        private readonly AppConfig _appConfig;
        public AppSettingsController(AppConfig appConfig)
        {
            _appConfig = appConfig;
        } 
 // codes here …
}

"UserOptionConfig": {
    "UsersAvatarsFolder": "avatars",
    "UserDefaultPhoto": "icon-user-default.png",
    "UserAvatarImageOptions": {
         "MaxWidth": 150,
         "MaxHeight": 150
    }
},

"LiteDbConfig": {
   "ConnectionString": "Filename=\\Data\\DependencyInjectionDemo.db;Connection=direct;Password=@123456;"
}

services.AddSingleton(services => new LiteDbConfig
{
    ConnectionString = this.Configuration["LiteDbConfig:ConnectionString"],
});

namespace AspNetCoreDependencyInjection.Configs
{
    public class UserOptionConfig
    {
        public string UsersAvatarsFolder { get; set; }
        public string UserDefaultPhoto { get; set; }
        public UserAvatarImageOptions UserAvatarImageOptions { get; set; }
    }

    public class UserAvatarImageOptions
    {
        public int MaxHeight { get; set; }
        public int MaxWidth { get; set; }
    }
}

services.Configure<UserOptionConfig>(this.Configuration.GetSection("UserOptionConfig"));

private readonly LiteDbConfig _liteDbConfig;
private readonly AppConfig _appConfig;
private readonly UserOptionConfig _userOptionConfig; 

public AppSettingsController(AppConfig appConfig ,
    LiteDbConfig liteDbConfig ,
    IOptionsMonitor<UserOptionConfig> userOptionConfig)
{
    _appConfig = appConfig;
    _liteDbConfig = liteDbConfig;
    _userOptionConfig = userOptionConfig.CurrentValue;
}

Install-Package iTextSharp

            //  درج لوگوی مسابقات به صورت شفاف در پس زمینه
            var canvas = pdfWriter.DirectContentUnder;
            var logoImg = Image.GetInstance(competitionImagePath);
            logoImg.SetAbsolutePosition(0, 0);
            logoImg.ScaleAbsolute(pageSize);
            var graphicsState = new PdfGState { FillOpacity = 0.2F };
            canvas.SetGState(graphicsState);
            canvas.AddImage(logoImg);

چیدمان و طرح بندی بندی عناصر در iTextSharp

برای طراحی کارت یا کلا کار طراحی، باید با نحوه‌ی قرار دادن و طرح بندی عناصر مثل تصاویر و نوشته‌ها و ابزارهای مورد نیاز برای این کار، آشنا شوید. خوشبختانه در iText برای این کار ابزارهای خوبی وجود دارد.

حتما با تگ Table در HTML آشنایی دارید. در سال‌های دور، حتی کل صفحه‌ی وب را به وسیله‌ی Table ساختار دهی می‌کردند. در iTextSharp نیز کلاسی به نام PdfPTable در دسترس است که می‌توان از آن به عنوان قالبی برای قرار دادن عناصر، در صفحه استفاده کرد. این Table همانند هر جدولی دارای یک سری سطر و ستون است که می‌توانیم عناصر مورد نظرمان مثل تصویر و نوشته و... را در آن قرار دهیم. 

public class UserAccountManager  : IUserAccountManager 
{
     private I,serRepository _userRepository ; 
     // تزریق درون سازنده
}

public class UserFinancialManager  : IUserFinancialManager  
{
     private IUserRepository _userRepository ; 
     // تزریق درون سازنده
}


public class UserController 
{
     IUserFinancialManager  _userFinancialManager ;
     IUserAccountManager  _userAccountManager;

     // تزریق درون سازنده
}

using System;

namespace AspNetCoreDependencyInjection.Services
{
    public interface IUserRepository
    {
        public string GID { get; }
    }

    public class UserRepository : IUserRepository
    {
        public string GID { get; private set; }

        public UserRepository()
        {
            GID = Guid.NewGuid().GetHashCode().ToString("x");
        }
    }

    //---------------------------------------------

    public interface IUserAccountManager
    {
        public string DisplayGuid();
    }

    public class UserAccountManager : IUserAccountManager
    {
        private IUserRepository _userRepository;

        public UserAccountManager(IUserRepository userRepository)
        {
            _userRepository = userRepository;
        }

        public string DisplayGuid()
        {
            return "UserFinancialManager Guid : " + _userRepository.GID;
        }
    }

    //-------------------------------------------------

    public interface IUserFinancialManager
    {
        public string DisplayGuid();
    }

    public class UserFinancialManager : IUserFinancialManager
    {
        private IUserRepository _userRepository;

        public UserFinancialManager(IUserRepository userRepository)
        {
            _userRepository = userRepository;
        }

        public string DisplayGuid()
        {
            return "UserFinancialManager Guid : " + _userRepository.GID;
        }
    }
}

public class UserController : Controller
    {
       
        private readonly IUserFinancialManager _userFinancialManager;

        private readonly IUserAccountManager _userAccountManager;

        public UserController(IUserFinancialManager userFinancialManager,
            IUserAccountManager userAccountManager)
        {
            _userFinancialManager = userFinancialManager;
            _userAccountManager = userAccountManager;
        }

        public IActionResult Index()
        {
            ViewBag.FinancialManager = _userFinancialManager.DisplayGuid();
            ViewBag.AccountManager = _userAccountManager.DisplayGuid();
            return View();
        }
    }

@{
ViewData["Title"] = "User";
}

<div class="text-center">
<div class="row">
<div class="col-12">
<p class="alert alert-info text-left">
<b>User Finanacial Manager / UserRepository Guid  : </b><span>@ViewBag.FinancialManager </span> <br />
<b>User Account Manager / UserRepository Guid  : </b><span>@ViewBag.AccountManager</span> <br />
</p>
</div>
</div>
</div>

 services.AddTransient<IUserRepository, UserRepository>();
 services.AddScoped<IUserAccountManager, UserAccountManager>();
services.AddScoped<IUserFinancialManager, UserFinancialManager>();


// اجرای دوم 
// services.AddScoped<IUserRepository, UserRepository>();
 //services.AddScoped<IUserAccountManager, UserAccountManager>();
//services.AddScoped<IUserFinancialManager, UserFinancialManager>();