public class UserModel   
{
   [Required, EmailAddress]
   public string Email { get; set; }
 
   [Required, StringLength(1000)]
   public string Name { get; set; }
}

public IActionResult SaveUser(UserModel model)
{
     if(!ModelState.IsValid)
     {

public IActionResult SaveUser(
     [Required, EmailAddress] string Email  
     [Required, StringLength(1000)] string Name)
{
    if(!ModelState.IsValid)

public IActionResult Get([BindRequired, FromRoute] Guid testId, [BindRequired, FromQuery] int qty)   
{
   if(!ModelState.IsValid)

چرا مسیریابی نشانه ای

routes.MapRoute(
    name: "ProductPage",
    url: "{productId}/{productTitle}",
    defaults: new { controller = "Products", action = "Show" },
    constraints: new { productId = "\\d+" }
);

[Route("{productId:int}/{productTitle}")]
public ActionResult Show(int productId) { ... }

فعال سازی Attribute Routing

public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
 
        routes.MapMvcAttributeRoutes();
    }
}

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
 
    routes.MapMvcAttributeRoutes();
 
    routes.MapRoute(
        name: "Default",
        url: "{controller}/{action}/{id}",
        defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
    );
}

پارامترهای اختیاری URI و مقادیر پیش فرض

public class BooksController : Controller
{
    // eg: /books
    // eg: /books/1430210079
    [Route("books/{isbn?}")]
    public ActionResult View(string isbn)
    {
        if (!String.IsNullOrEmpty(isbn))
        {
            return View("OneBook", GetBook(isbn));
        }
        return View("AllBooks", GetBooks());
    }
 
    // eg: /books/lang
    // eg: /books/lang/en
    // eg: /books/lang/he
    [Route("books/lang/{lang=en}")]
    public ActionResult ViewByLanguage(string lang)
    {
        return View("OneBook", GetBooksByLanguage(lang));
    }
}

پیشوند مسیرها (Route Prefixes)

public class ReviewsController : Controller
{
    // eg: /reviews
    [Route("reviews")]
    public ActionResult Index() { ... }
    // eg: /reviews/5
    [Route("reviews/{reviewId}")]
    public ActionResult Show(int reviewId) { ... }
    // eg: /reviews/5/edit
    [Route("reviews/{reviewId}/edit")]
    public ActionResult Edit(int reviewId) { ... }
}

[RoutePrefix("reviews")]
public class ReviewsController : Controller
{
    // eg.: /reviews
    [Route]
    public ActionResult Index() { ... }
    // eg.: /reviews/5
    [Route("{reviewId}")]
    public ActionResult Show(int reviewId) { ... }
    // eg.: /reviews/5/edit
    [Route("{reviewId}/edit")]
    public ActionResult Edit(int reviewId) { ... }
}

[RoutePrefix("reviews")]
public class ReviewsController : Controller
{
    // eg.: /spotlight-review
    [Route("~/spotlight-review")]
    public ActionResult ShowSpotlight() { ... }
 
    ...
}

مسیر پیش فرض

[RoutePrefix("promotions")]
[Route("{action=index}")]
public class ReviewsController : Controller
{
    // eg.: /promotions
    public ActionResult Index() { ... }
 
    // eg.: /promotions/archive
    public ActionResult Archive() { ... }
 
    // eg.: /promotions/new
    public ActionResult New() { ... }
 
    // eg.: /promotions/edit/5
    [Route("edit/{promoId:int}")]
    public ActionResult Edit(int promoId) { ... }
}

محدودیت‌های مسیر ها

// eg: /users/5
[Route("users/{id:int}"]
public ActionResult GetUserById(int id) { ... }
 
// eg: users/ken
[Route("users/{name}"]
public ActionResult GetUserByName(string name) { ... }

public static void CreateUniqueIndex(this DbContext context, string tableName, string fieldName)
{
      context.Database.ExecuteSqlCommand("CREATE UNIQUE INDEX [IX_Unique_" + tableName 
+ "_" + fieldName + "] ON [" + tableName + "]([" + fieldName + "] ASC);");
}

public class MyDbMigrationsConfiguration : DbMigrationsConfiguration<MyContext>
{
        public BlogDbMigrationsConfiguration()
        {
            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;
        }

        protected override void Seed(MyContext context)
        {
            CreateUniqueIndex(context, "table1", "field1");
            base.Seed(context);
        }
}

using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Data.Objects;
using System.Linq;
using System.Linq.Expressions;
using System.Text.RegularExpressions;

namespace General
{
    public static class ContextExtensions
    {
        public static string GetTableName<T>(this DbContext context) where T : class
        {
            ObjectContext objectContext = ((IObjectContextAdapter)context).ObjectContext;
            return objectContext.GetTableName<T>();
        }

        public static string GetTableName<T>(this ObjectContext context) where T : class
        {
            var sql = context.CreateObjectSet<T>().ToTraceString();
            var regex = new Regex("FROM (?<table>.*) AS");
            var match = regex.Match(sql);
            string table = match.Groups["table"].Value;
            return table
                    .Replace("`", string.Empty)
                    .Replace("[", string.Empty)
                    .Replace("]", string.Empty)
                    .Replace("dbo.", string.Empty)
                    .Trim();
        }

        private static bool hasUniqueIndex(this DbContext context, string tableName, string indexName)
        {
            var sql = "SELECT count(*) FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS where table_name = '" 
                      + tableName + "' and CONSTRAINT_NAME = '" + indexName + "'";
            var result = context.Database.SqlQuery<int>(sql).FirstOrDefault();
            return result > 0;
        }

        private static void createUniqueIndex(this DbContext context, string tableName, string fieldName)
        {
            var indexName = "IX_Unique_" + tableName + "_" + fieldName;
            if (hasUniqueIndex(context, tableName, indexName))
                return;

            var sql = "ALTER TABLE [" + tableName + "] ADD CONSTRAINT [" + indexName + "] UNIQUE ([" + fieldName + "])";
            context.Database.ExecuteSqlCommand(sql);
        }

        public static void CreateUniqueIndex<TEntity>(this DbContext context, Expression<Func<TEntity, object>> fieldName) where TEntity : class
        {
            var field = ((MemberExpression)fieldName.Body).Member.Name;
            createUniqueIndex(context, context.GetTableName<TEntity>(), field);
        }
    }
}

context.CreateUniqueIndex<User>(x=>x.Name);

class LoginForm extends Component {
  state = {
    account: { username: "", password: "" },
    errors: {
      username: "Username is required"
    }
  };

  validate = () => {
    return { username: "Username is required." };
  };

  handleSubmit = e => {
    e.preventDefault();

    const errors = this.validate();
    console.log("Validation errors", errors);
    this.setState({ errors });
    if (errors) {
      return;
    }

    // call the server
    console.log("Submitted!");
  };

  validate = () => {
    const { account } = this.state;

    const errors = {};
    if (account.username.trim() === "") {
      errors.username = "Username is required.";
    }

    if (account.password.trim() === "") {
      errors.password = "Password is required.";
    }

    return Object.keys(errors).length === 0 ? null : errors;
  };

import React from "react";

const Input = ({ name, label, value, error, onChange }) => {
  return (
    <div className="form-group">
      <label htmlFor={name}>{label}</label>
      <input
        value={value}
        onChange={onChange}
        id={name}
        name={name}
        type="text"
        className="form-control"
      />
      {error && <div className="alert alert-danger">{error}</div>}
    </div>
  );
};

export default Input;

  render() {
    const { account, errors } = this.state;
    return (
      <form onSubmit={this.handleSubmit}>
        <Input
          name="username"
          label="Username"
          value={account.username}
          onChange={this.handleChange}
          error={errors.username}
        />
        <Input
          name="password"
          label="Password"
          value={account.password}
          onChange={this.handleChange}
          error={errors.password}
        />
        <button className="btn btn-primary">Login</button>
      </form>
    );
  }

loginForm.jsx:55 Uncaught TypeError: Cannot read property 'username' of null
at LoginForm.render (loginForm.jsx:55)

this.setState({ errors: errors || {} });

  handleChange = ({ currentTarget: input }) => {
    const errors = { ...this.state.errors }; //cloning an object
    const errorMessage = this.validateProperty(input);
    if (errorMessage) {
      errors[input.name] = errorMessage;
    } else {
      delete errors[input.name];
    }

    const account = { ...this.state.account }; //cloning an object
    account[input.name] = input.value;

    this.setState({ account, errors });
  };

  validateProperty = ({ name, value }) => {
    if (name === "username") {
      if (value.trim() === "") {
        return "Username is required.";
      }
      // ...
    }

    if (name === "password") {
      if (value.trim() === "") {
        return "Password is required.";
      }
      // ...
    }
  };

const Joi = require('@hapi/joi');
const schema = Joi.object({
    username: Joi.string().alphanum().min(3).max(30).required(),
    password: Joi.string().pattern(/^[a-zA-Z0-9]{3,30}$/),
    email: Joi.string().email({ minDomainSegments: 2, tlds: { allow: ['com', 'net'] } })
});
schema.validate({ username: 'abc', birth_year: 1994 });

> npm install @hapi/joi --save
> npm i --save-dev @types/hapi__joi

import Joi from "@hapi/joi";

  schema = {
    username: Joi.string()
      .required()
      .label("Username"),
    password: Joi.string()
      .required()
      .label("Password")
  };

  validate = () => {
    const { account } = this.state;
    const validationResult = Joi.object(this.schema).validate(account, {
      abortEarly: false
    });
    console.log("validationResult", validationResult);

  validate = () => {
    const { account } = this.state;
    const validationResult = Joi.object(this.schema).validate(account, {
      abortEarly: false
    });
    console.log("validationResult", validationResult);

    if (!validationResult.error) {
      return null;
    }

    const errors = {};
    for (let item of validationResult.error.details) {
      errors[item.path[0]] = item.message;
    }
    return errors;
  };

  validateProperty = ({ name, value }) => {
    const userInputObject = { [name]: value };
    const propertySchema = Joi.object({ [name]: this.schema[name] });
    const { error } = propertySchema.validate(userInputObject, {
      abortEarly: true
    });
    return error ? error.details[0].message : null;
  };

 <button disabled={this.validate()} className="btn btn-primary">
 Login
</button>

 PM> install-package Newtonsoft.Json

 var roles = new List<string>
{
   "Admin",
   "User"
};
string json = JsonConvert.SerializeObject(roles, Formatting.Indented);

 var jsonString = JsonConvert.SerializeObject(new
{
   Id =1,
   Name = "Test"
}, Formatting.Indented);

var jsonData = JsonConvert.SerializeObject(new
{
   Id = 1,
   Name = "Test",
   DateTime = DateTime.Now
}, new JsonSerializerSettings
{
   Formatting = Formatting.Indented,
   Converters =
   {
      new JavaScriptDateTimeConverter()
   }
});

 {
  "Id": 1,
  "Name": "Test",
  "DateTime": new Date(1409821985245)
}

using (var stream = File.CreateText(@"c:\output.json"))
{
    var jsonSerializer = new JsonSerializer
   {
      Formatting = Formatting.Indented
   };
   jsonSerializer.Serialize(stream, new
   {
     Id = 1,
     Name = "Test",
     DateTime = DateTime.Now
   });
}

public class User
{
   public int Id { set; get; }
   public string Name { set; get; }
   public DateTime DateTime { set; get; }
}

 var user = JsonConvert.DeserializeObject<User>(jsonData);

var user = JsonConvert.DeserializeObject<User>(jsonData, new JsonSerializerSettings
{
   Converters = {  new JavaScriptDateTimeConverter() }
});

 JsonConvert.PopulateObject(jsonData, user);

var jsonData = JsonConvert.SerializeObject(object, new JsonSerializerSettings
{
   NullValueHandling = NullValueHandling.Ignore,
   Formatting = Formatting.Indented
});

public class Employee
{
    public string Name { set; get; }
}

public class Manager : Employee
{
    public IList<Employee> Reports { set; get; }
}

 var employee = new Employee { Name = "User1" };
var manager1 = new Manager { Name = "User2" };
var manager2 = new Manager { Name = "User3" };
manager1.Reports = new[] { employee, manager2 };
manager2.Reports = new[] { employee };

 var list = JsonConvert.SerializeObject(manager1, Formatting.Indented);

{
  "Reports": [
    {
      "Name": "User1"
    },
    {
      "Reports": [
        {
          "Name": "User1"
        }
      ],
      "Name": "User3"
    }
  ],
  "Name": "User2"
}

var list = JsonConvert.SerializeObject(manager1, new JsonSerializerSettings
{
   Formatting = Formatting.Indented,
   TypeNameHandling = TypeNameHandling.Objects,
   PreserveReferencesHandling = PreserveReferencesHandling.Objects
});
 

{
  "$id": "1",
  "$type": "JsonNetTests.Manager, JsonNetTests",
  "Reports": [
    {
      "$id": "2",
      "$type": "JsonNetTests.Employee, JsonNetTests",
      "Name": "User1"
    },
    {
      "$id": "3",
      "$type": "JsonNetTests.Manager, JsonNetTests",
      "Reports": [
        {
          "$ref": "2"
        }
      ],
      "Name": "User3"
    }
  ],
  "Name": "User2"
}

public class User
{
   public int Id { set; get; }

   [JsonIgnore]
   public string Name { set; get; }

   public DateTime DateTime { set; get; }
}

[JsonProperty(PropertyName = "m_name", NullValueHandling = NullValueHandling.Ignore)]
public string Name { set; get; }

[JsonObject(MemberSerialization.OptIn)]
public class User
{
    public int Id { set; get; }

    [JsonProperty]
    public string Name { set; get; }
 
    public DateTime DateTime { set; get; }
}

[JsonConverter(typeof(JavaScriptDateTimeConverter))]
public DateTime DateTime { set; get; }

public class HtmlColor
{
   public int Red { set; get; }
   public int Green { set; get; }
   public int Blue { set; get; }
}

var colorJson = JsonConvert.SerializeObject(new HtmlColor
{
  Red = 255,
  Green = 0,
  Blue = 0
}, Formatting.Indented);

    public class HtmlColorConverter : JsonConverter
    {

        public override bool CanConvert(Type objectType)
        {
            return objectType == typeof(HtmlColor);
        }

        public override object ReadJson(JsonReader reader, Type objectType,
                                        object existingValue, JsonSerializer serializer)
        {
            throw new NotSupportedException();
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            var color = value as HtmlColor;
            if (color == null)
                return;

            writer.WriteValue("#" + color.Red.ToString("X2")
                + color.Green.ToString("X2") + color.Blue.ToString("X2"));
        }
    }

var colorJson = JsonConvert.SerializeObject(new HtmlColor
{
  Red = 255,
  Green = 0,
  Blue = 0
},  new JsonSerializerSettings
    {
      Formatting = Formatting.Indented,
      Converters = { new HtmlColorConverter() }
    });   

    // Main method 
    public static void Main()
    {
        // Local Function 
        void AddValue(int a, int b)
        {
            Console.WriteLine("Value of a is: " + a);
            Console.WriteLine("Value of b is: " + b);
            Console.WriteLine("Sum of a and b is: {0}", a + b);
            Console.WriteLine();
        }

        // Calling Local function 
        AddValue(20, 40);
        AddValue(40, 60);
    }

        static void Main(string[] args)
        {
            static void DoAction()
            {
                // DoAction

                Console.WriteLine("DoAction...");
            }

#if DEBUG
            DoAction();
#endif
        }

        static void Main(string[] args)
        {
            [Conditional("DEBUG")]
            static void DoAction()
            {
                // Do Action Here

                Console.WriteLine("Do Action...");
            }

            DoAction();
        }

ErrorCS8400Feature 'local function attributes' is not available in C# 8.0. Please use language version 9.0 or greater.