// Entity Framework Classic

// Doc: https://entityframework-classic.net/query-result-filter

​

// @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.QueryResultFilter.DisableFilter(context.FilterID);

            // SELECT * FROM Customers

            var list = context.Customers.ToList();

            FiddleHelper.WriteTable("QueryResultFilterManager.DisableFilter(string id)", list);         

        }

        using (var context = new EntityContext())

        {

            context.Configuration.QueryResultFilter.EnableFilter(context.FilterID);

            // SELECT * FROM Customers WHERE IsDeleted = 0

            var list = context.Customers.ToList();

            FiddleHelper.WriteTable("QueryResultFilterManager.EnableFilter(string id)", list);          

        }

    }

    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", IsDeleted = true });           

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

            context.SaveChanges();  

        }

    }

​

    public class EntityContext : DbContext

    {

        public string FilterID = "id_001";

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

        {       

            // Add your QueryResultFilter here

            this.Configuration.QueryResultFilter.Filter<ISoftDelete>(FilterID ,customer => !customer.IsDeleted || this.DisplaySoftDelete());

        }

        public bool DisplaySoftDelete()

        {

            // Check for example if current user has admin right

            return false;

        }

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

    }

    public interface ISoftDelete

    {

        bool IsDeleted { get; set; }

    }

    public class Customer : ISoftDelete

    {

        public int CustomerID { get; set; }

        public string Name { get; set; }

        public string Description { get; set; }

        public bool IsDeleted { get; set; }

    }

}