// Dynamic LINQ - stef

​

// @nuget: System.Linq.Dynamic.Core

// @nuget: Z.EntityFramework.Classic

​

using System;

using System.Collections.Generic;

using System.Linq;

using System.Data.Entity;

using System.Linq.Dynamic.Core;

using System.Linq.Dynamic.Core.CustomTypeProviders;

using System.ComponentModel.DataAnnotations;

public class Program

{   

    public static void Main()

    {

        GenerateData();

        var context = new EntityContext();

        var result = context.X.Select("Utils.ParseAsInt(Value)");

        FiddleHelper.WriteTable(result);

    }

    public static void GenerateData()

    {

        var list = new List<X>

        {

            new X { Value = null },

            new X { Value = "100" }

        };

        using (var context = new EntityContext())

        {

            context.X.AddRange(list);

            context.BulkSaveChanges();

        }

    }

    public class EntityContext : DbContext

    {

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

        {

        }

        public DbSet<X> X { get; set; }

    }

    public class X

    {

        public int Id { get; set; }

        public string Value { get; set; }

    }

    [DynamicLinqType]

    public static class Utils

    {

        public static int ParseAsInt(string value)

        {

            if (value == null)

            {

                 return 0;

            }

​

            return int.Parse(value);

        }

    }

}