// Entity Framework Classic

// Doc: https://entityframework-classic.net/query-future

​

// @nuget: Z.EntityFramework.Classic

​

using System;

using System.Linq;

using System.Data.Entity;

​

public class Program

{

    public static void Main()

    {

        GenerateData();

​

        using (var context = new EntityContext())

        {

            context.Configuration.QueryFuture.IsEnabled = true;

            // CREATE a pending list of future queries

            var customers_1 = context.Customers.Where(x => x.Name == "Customer_D").Future();

            var customers_2 = context.Customers.Where(x => x.Name == "Customer_E").Future();

            // TRIGGER all pending queries in one database round trip

            FiddleHelper.WriteTable("IsEnabled true 1 - Customer", customers_1);    

            context.Customers.Add(new Customer() { Name ="Customer_D", Description = "Description" });

            context.Customers.Add(new Customer() { Name ="Customer_E", Description = "Description" });

            context.SaveChanges();

            FiddleHelper.WriteTable("IsEnabled true 2 - Customer", customers_2);        

        }

        using (var context = new EntityContext())

        {

            context.Customers.RemoveRange(context.Customers.Where(x => x.Name =="Customer_D" || x.Name =="Customer_E"  ));

            context.SaveChanges();

        }

        using (var context = new EntityContext())

        {

            context.Configuration.QueryFuture.IsEnabled = false;

            /// CREATE a pending list of future queries

            var customers_1 = context.Customers.Where(x => x.Name == "Customer_D").Future();

            var customers_2 = context.Customers.Where(x => x.Name == "Customer_E").Future();

            // TRIGGER one pending queries

            FiddleHelper.WriteTable("IsEnabled false 1 - Customer", customers_1);   

            context.Customers.Add(new Customer() { Name ="Customer_D", Description = "Description" });

            context.Customers.Add(new Customer() { Name ="Customer_E", Description = "Description" });

            context.SaveChanges();

            FiddleHelper.WriteTable("IsEnabled false 2 - Customer", customers_2);           

        }

    }

    public static void GenerateData()

    {

        using (var context = new EntityContext())

        {

            context.Customers.Add(new Customer() { Name ="Customer_A", Description = "Description" });

            context.Customers.Add(new Customer() { Name ="Customer_B", Description = "Description" });          

            context.Customers.Add(new Customer() { Name ="Customer_C", Description = "Description" });

            context.SaveChanges();  

        }

    }

​

    public class EntityContext : DbContext

    {

        public EntityContext() : base(FiddleHelper.GetConnectionStringSqlServer())

        {

​

        }

        public DbSet<Customer> Customers { get; set; }

    }

    public class Customer

    {

        public int CustomerID { get; set; }

        public string Name { get; set; }

        public string Description { get; set; }

    }

}