To Update 
PM> Update-Package EntityFramework -Version 6.2.0

To install
PM> Install-Package EntityFramework -Version 6.2.0

public class MyDbConfiguration : DbConfiguration
{
   public MyDbConfiguration() : base()
   {
       SetModelStore(new DefaultDbModelStore(Directory.GetCurrentDirectory()));
   }
}

 /bin/Debug/MyAssembly.MyNamespace.MyDbContext.edmx

var appDataDirectory = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data");
//OR
var appDataDirectory = AppDomain.CurrentDomain.GetData("DataDirectory").ToString();
 

حین فراخوانی متد Html.Action، یک متد در یک کنترلر فراخوانی خواهد شد (که شامل ارائه درخواست و طی سیکل کامل پردازشی آن کنترلر نیز خواهد بود). سپس آن متد با بازگشت دادن یک PartialView، اطلاعات پردازش شده یک partial view را به فراخوان بازگشت می‌دهد 

 return PartialView("_Contact", model);

 if (this.ModelState.IsValid)
            {
                
                return RedirectToAction(actionName: "show", controllerName:"Posts", routeValues: new { id });
            }

Child actions are not allowed to perform redirect actions. 

/// <summary>
/// افزودن و مدیریت کاربران سیستم
/// </summary>
[PageAuthorization(AuthorizationType.ApplyRequiredRoles, "IsAdmin, CanAddNewUser")]

                <Button Style="{DynamicResource MetroCircleButtonStyle}"
                        Height="55" Width="55"  
                        Command="{Binding DoNavigate}"
                        CommandParameter="\Views\Admin\AddNewUser.xaml"
                        Margin="2">
                    <Rectangle Width="28" Height="17.25">
                        <Rectangle.Fill>
                            <VisualBrush Stretch="Fill" Visual="{StaticResource appbar_user_add}" />
                        </Rectangle.Fill>
                    </Rectangle>
                </Button>

public ObservableCollection<User> UsersList { set; get; }

        /// <summary>
        /// جهت مقاصد انقیاد داده‌ها در دبلیو پی اف طراحی شده است
        /// لیستی از کاربران سیستم را باز می‌گرداند
        /// </summary>
        /// <param name="count">تعداد کاربر مد نظر</param>
        /// <returns>لیستی از کاربران</returns>
        public ObservableCollection<User> GetSyncedUsersList(int count = 1000)
        {
            _users.OrderBy(x => x.FriendlyName).Take(count)
                  .Load();

            // For Databinding with WPF.
            // Before calling this method you need to fill the context by using `Load()` method.
            return _users.Local;
        }

  /// <summary>
  /// فعال و غیرفعال سازی خودکار دکمه ثبت
  /// این متد به صورت خودکار توسط RelayCommand کنترل می‌شود
  /// </summary>  
  private bool canDoSave()
  {
     // آیا در حین نمایش صفحه‌ای دیگر باید به کاربر پیغام داد که اطلاعات ذخیره نشده‌ای وجود دارد؟
     return ViewModelContextHasChanges;
  }

  /// <summary>
  /// رخداد ذخیره سازی اطلاعات را دریافت می‌کند
  /// </summary>
  public RelayCommand DoSave { set; get; }

DoSave = new RelayCommand(doSave, canDoSave);

public double Area
{
        get { return _height * _baseLength * 0.5; }
}

public double Area()
{
      return _height * _baseLength * 0.5;
}

@page.Html.Raw(data)

    public struct Optional<T>
    {
        public bool HasValue { get; }
        public T Value { get; }
    }

class ConsoleWriteLineWalker : CSharpSyntaxWalker
{
    public ConsoleWriteLineWalker()
    {
        Arguments = new List<ExpressionSyntax>();
    }
 
    public List<ExpressionSyntax> Arguments { get; }
 
    public override void VisitInvocationExpression(InvocationExpressionSyntax node)
    {
        var member = node.Expression as MemberAccessExpressionSyntax;
        var type = member?.Expression as IdentifierNameSyntax;
        if (type != null && type.Identifier.Text == "Console" && member.Name.Identifier.Text == "WriteLine")
        {
            if (node.ArgumentList.Arguments.Count == 1)
            {
                var arg = node.ArgumentList.Arguments.Single().Expression;
                Arguments.Add(arg);
                return;
            }
        }
 
        base.VisitInvocationExpression(node);
    }
}

static void getConstantValue()
{
    // Get the syntax tree.
    var code = @"
                using System;
 
                class Foo
                {
                    void Bar(int x)
                    {
                        Console.WriteLine(3.14);
                        Console.WriteLine(""qux"");
                        Console.WriteLine('c');
                        Console.WriteLine(null);
                        Console.WriteLine(x * 2 + 1);
                    }
                }
                ";
 
    var tree = CSharpSyntaxTree.ParseText(code);
    var root = tree.GetRoot();
 
    // Get the semantic model from the compilation.
    var mscorlib = MetadataReference.CreateFromFile(typeof(object).Assembly.Location);
    var comp = CSharpCompilation.Create("Demo").AddSyntaxTrees(tree).AddReferences(mscorlib);
    var model = comp.GetSemanticModel(tree);
 
    // Traverse the tree.
    var walker = new ConsoleWriteLineWalker();
    walker.Visit(root);
 
 
    // Analyze the constant argument (if any).
    foreach (var arg in walker.Arguments)
    {
        var val = model.GetConstantValue(arg);
        if (val.HasValue)
        {
            Console.WriteLine(arg + " has constant value " + (val.Value ?? "null") + " of type " + (val.Value?.GetType() ?? typeof(object)));
        }
        else
        {
            Console.WriteLine(arg + " has no constant value");
        }
    }
}

 3.14 has constant value 3.14 of type System.Double
"qux" has constant value qux of type System.String
'c' has constant value c of type System.Char
null has constant value null of type System.Object
x * 2 + 1 has no constant value

static void workingWithSymbols()
{
    // Get the syntax tree.
    var code = @"
                using System;
 
                class Foo
                {
                    void Bar(int x)
                    {
                        // #insideBar
                    }
                }
 
                class Qux
                {
                    protected int Baz { get; set; }
                }
                ";
 
    var tree = CSharpSyntaxTree.ParseText(code);
    var root = tree.GetRoot();
 
    // Get the semantic model from the compilation.
    var mscorlib = MetadataReference.CreateFromFile(typeof(object).Assembly.Location);
    var comp = CSharpCompilation.Create("Demo").AddSyntaxTrees(tree).AddReferences(mscorlib);
    var model = comp.GetSemanticModel(tree);
 
    // Traverse enclosing symbol hierarchy.
    var cursor = code.IndexOf("#insideBar");
    var barSymbol = model.GetEnclosingSymbol(cursor);
    for (var symbol = barSymbol; symbol != null; symbol = symbol.ContainingSymbol)
    {
        Console.WriteLine(symbol);
    }
 
    // Analyze accessibility of Baz inside Bar.
    var bazProp = ((CompilationUnitSyntax)root)
        .Members.OfType<ClassDeclarationSyntax>()
        .Single(m => m.Identifier.Text == "Qux")
        .Members.OfType<PropertyDeclarationSyntax>()
        .Single();
    var bazSymbol = model.GetDeclaredSymbol(bazProp);
    var canAccess = model.IsAccessible(cursor, bazSymbol);
}

 Foo.Bar(int)
Foo
<global namespace>
Demo.exe
Demo, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null

static void bindingSymbols()
{
    // Get the syntax tree.
    var code = @"
                using System;
 
                class Foo
                {
                    private int y;
 
                    void Bar(int x)
                    {
                        Console.WriteLine(x);
                        Console.WriteLine(y);
 
                        int z = 42;
                        Console.WriteLine(z);
 
                        Console.WriteLine(a);
                    }
                }";
 
    var tree = CSharpSyntaxTree.ParseText(code);
    var root = tree.GetRoot();
 
    // Get the semantic model from the compilation.
    var mscorlib = MetadataReference.CreateFromFile(typeof(object).Assembly.Location);
    var comp = CSharpCompilation.Create("Demo").AddSyntaxTrees(tree).AddReferences(mscorlib);
    var model = comp.GetSemanticModel(tree);
 
    // Traverse the tree.
    var walker = new ConsoleWriteLineWalker();
    walker.Visit(root);
 
    // Bind the arguments.
    foreach (var arg in walker.Arguments)
    {
        var symbol = model.GetSymbolInfo(arg);
        if (symbol.Symbol != null)
        {
            Console.WriteLine(arg + " is bound to " + symbol.Symbol + " of type " + symbol.Symbol.Kind);
        }
        else
        {
            Console.WriteLine(arg + " could not be bound");
        }
    }
}

 x is bound to int of type Parameter
y is bound to Foo.y of type Field
z is bound to z of type Local
a could not be bound

using Microsoft.AspNetCore.Http;

public class Startup
{
    public void Configure(IApplicationBuilder app)
    {
        app.Use(async (context, next) =>
        {
            await context.Response.WriteAsync("<div>from middleware-1, inside app.Use, before next()</div>");
 
            await next();
 
            await context.Response.WriteAsync("<div>from middleware-1, inside app.Use, after next()</div>");
        });
 
        app.Run(async context =>
        {
            await context.Response.WriteAsync("<div>Inside middleware-2 defined using app.Run</div>");
        });
 
        app.Use(async (context, next) =>
        {
            await context.Response.WriteAsync("<div>from middleware-3, inside app.Use, before next()</div>");
 
            await next();
 
            await context.Response.WriteAsync("<div>from middleware-3, inside app.Use, after next()</div>");
        });

 public delegate Task RequestDelegate(HttpContext context);

app.Map("/dnt", appBuilder =>
{
    appBuilder.Run(async context =>
    {
        await context.Response.WriteAsync(@"<div>Inside Map(/dnt) --> Run</div>");
    });
});

app.MapWhen(context =>
{
    return context.Request.Query.ContainsKey("dnt");
},
appBuilder =>
{
    appBuilder.Run(async context =>
    {
        await context.Response.WriteAsync(@"<div>Inside MapWhen(?dnt) --> Run</div>");
    });
});

 http://localhost:7742/?dnt=true

using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
 
namespace Core1RtmEmptyTest.StartupCustomizations
{
    public class MyMiddleware1
    {
        private readonly RequestDelegate _next;
 
        public MyMiddleware1(RequestDelegate next)
        {
            _next = next;
        }
 
        public async Task Invoke(HttpContext context)
        {
                    context.Response.ContentType = "text/html";
                    context.Response.StatusCode = 200;
            await context.Response.WriteAsync("<div>Hello from MyMiddleware1.</div>");
            await _next.Invoke(context);
            await context.Response.WriteAsync("<div>End of action.</div>");
        }
    } 
}

using Microsoft.AspNetCore.Builder;

public static class MyMiddlewareExtensions
{
    public static IApplicationBuilder UseMyMiddleware(this IApplicationBuilder app)
    {
        app.UseMiddleware<MyMiddleware1>();
        return app;
    }
}

public void Configure(IApplicationBuilder app)
{
    app.UseMyMiddleware();

سورس مثال فوق را هم از اینجا  می توانید دریافت کنید.