मैं MySQL कनेक्टर/नेट के साथ 2 की गहराई से पहले ऑब्जेक्ट ग्राफ़ पर एंटिटी फ्रेमवर्क का उपयोग कैसे कर सकता हूं?

संपादित करें

नीचे दिया गया परीक्षण SQL सर्वर और SqlClient के साथ किया गया था प्रदाता के रूप में। तथ्य यह है कि समस्या SQL सर्वर के साथ पुन:उत्पन्न करने योग्य नहीं है, सवाल उठता है यदि MySql आपके द्वारा उपयोग किए जा रहे प्रदाता में एक बग है जो आपकी LINQ क्वेरी के लिए गलत SQL बनाता है। यह इस सवाल जैसी ही समस्या लगती है। जहां समस्या एक MySql . के साथ हुई प्रदाता के रूप में अच्छी तरह से और SqlClient . के साथ पुन:प्रस्तुत नहीं किया जा सका /एसक्यूएल सर्वर।

मैंने बोल्ड में उदाहरण का परीक्षण किया है (EF 4.3.1 के साथ) और समस्या को पुन:उत्पन्न नहीं कर सकता:

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;

namespace EFInclude
{
    public class Harbor
    {
        public int HarborId { get; set; }
        public virtual ICollection<Ship> Ships { get; set; }

        public string Description { get; set; }
    }

    public class Ship
    {
        public int ShipId { get; set; }
        public int HarborId { get; set; }
        public virtual Harbor Harbor { get; set; }
        public virtual ICollection<CrewMember> CrewMembers { get; set; }

        public string Description { get; set; }
    }

    public class CrewMember
    {
        public int CrewMemberId { get; set; }
        public int ShipId { get; set; }
        public virtual Ship Ship { get; set; }
        public int RankId { get; set; }
        public virtual Rank Rank { get; set; }
        public int ClearanceId { get; set; }
        public virtual Clearance Clearance { get; set; }

        public string Description { get; set; }
    }

    public class Rank
    {
        public int RankId { get; set; }
        public virtual ICollection<CrewMember> CrewMembers { get; set; }

        public string Description { get; set; }
    }

    public class Clearance
    {
        public int ClearanceId { get; set; }
        public virtual ICollection<CrewMember> CrewMembers { get; set; }

        public string Description { get; set; }
    }

    public class MyContext : DbContext
    {
        public DbSet<Harbor> Harbors { get; set; }
        public DbSet<Ship> Ships { get; set; }
        public DbSet<CrewMember> CrewMembers { get; set; }
        public DbSet<Rank> Ranks { get; set; }
        public DbSet<Clearance> Clearances { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Database.SetInitializer(new DropCreateDatabaseAlways<MyContext>());

            using (var context = new MyContext())
            {
                context.Database.Initialize(true);

                var harbor = new Harbor
                {
                    Ships = new HashSet<Ship>
                    {
                        new Ship
                        {
                            CrewMembers = new HashSet<CrewMember>
                            {
                                new CrewMember
                                {
                                    Rank = new Rank { Description = "Rank A" },
                                    Clearance = new Clearance { Description = "Clearance A" },
                                    Description = "CrewMember A"
                                },
                                new CrewMember
                                {
                                    Rank = new Rank { Description = "Rank B" },
                                    Clearance = new Clearance { Description = "Clearance B" },
                                    Description = "CrewMember B"
                                }
                            },
                            Description = "Ship AB"
                        },
                        new Ship
                        {
                            CrewMembers = new HashSet<CrewMember>
                            {
                                new CrewMember
                                {
                                    Rank = new Rank { Description = "Rank C" },
                                    Clearance = new Clearance { Description = "Clearance C" },
                                    Description = "CrewMember C"
                                },
                                new CrewMember
                                {
                                    Rank = new Rank { Description = "Rank D" },
                                    Clearance = new Clearance { Description = "Clearance D" },
                                    Description = "CrewMember D"
                                }
                            },
                            Description = "Ship CD"
                        }
                    },
                    Description = "Harbor ABCD"
                };

                context.Harbors.Add(harbor);
                context.SaveChanges();
            }

            using (var context = new MyContext())
            {
                DbSet<Harbor> dbSet = context.Set<Harbor>();
                IQueryable<Harbor> query = dbSet;
                query = query.Include(entity => entity.Ships);
                query = query.Include(entity => entity.Ships.Select(s => s.CrewMembers));
                query = query.Include(entity => entity.Ships.Select(s => s.CrewMembers.Select(cm => cm.Rank)));
                query = query.Include(entity => entity.Ships.Select(s => s.CrewMembers.Select(cm => cm.Clearance)));

                var sqlString = query.ToString();
                // see below for the generated SQL query

                var harbor = query.Single();

                Console.WriteLine("Harbor {0} Description = \"{1}\"",
                    harbor.HarborId, harbor.Description);
                foreach (var ship in harbor.Ships)
                {
                    Console.WriteLine("- Ship {0} Description = \"{1}\"",
                        ship.ShipId, ship.Description);
                    foreach (var crewMember in ship.CrewMembers)
                    {
                        Console.WriteLine("-- CrewMember {0} Description = \"{1}\"", 
                            crewMember.CrewMemberId, crewMember.Description);
                        Console.WriteLine("-- CrewMember {0} Rank Description = \"{1}\"",
                            crewMember.CrewMemberId, crewMember.Rank.Description);
                        Console.WriteLine("-- CrewMember {0} Clearance Description = \"{1}\"",
                            crewMember.CrewMemberId, crewMember.Clearance.Description);
                    }
                }

                Console.ReadLine();
            }
        }
    }
}

आउटपुट है:

आपके विवरण के अनुसार बोल्ड में मेरे पास होना चाहिए:CrewMember 1 विवरण ="रैंक A" और अन्य 3 चालक दल के सदस्यों के लिए भी यही गड़बड़ी। लेकिन मेरे पास यह नहीं है।

क्या आपके कोड की तुलना में मेरे परीक्षण कार्यक्रम में कुछ अलग है जहां आपको त्रुटि है?

संपादित करें

क्वेरी के लिए जेनरेट किया गया SQL (लाइन देखें var sqlString = query.ToString(); उपरोक्त स्रोत कोड में, sqlString की सामग्री निम्नलिखित है:) है:

SELECT 
[Project1].[HarborId] AS [HarborId], 
[Project1].[Description] AS [Description], 
[Project1].[C2] AS [C1], 
[Project1].[ShipId] AS [ShipId], 
[Project1].[HarborId1] AS [HarborId1], 
[Project1].[Description1] AS [Description1], 
[Project1].[C1] AS [C2], 
[Project1].[CrewMemberId] AS [CrewMemberId], 
[Project1].[ShipId1] AS [ShipId1], 
[Project1].[RankId] AS [RankId], 
[Project1].[ClearanceId] AS [ClearanceId], 
[Project1].[Description2] AS [Description2], 
[Project1].[RankId1] AS [RankId1], 
[Project1].[Description3] AS [Description3], 
[Project1].[ClearanceId1] AS [ClearanceId1], 
[Project1].[Description4] AS [Description4]
FROM ( SELECT 
    [Extent1].[HarborId] AS [HarborId], 
    [Extent1].[Description] AS [Description], 
    [Join3].[ShipId1] AS [ShipId], 
    [Join3].[HarborId] AS [HarborId1], 
    [Join3].[Description1] AS [Description1], 
    [Join3].[CrewMemberId] AS [CrewMemberId], 
    [Join3].[ShipId2] AS [ShipId1], 
    [Join3].[RankId1] AS [RankId], 
    [Join3].[ClearanceId1] AS [ClearanceId], 
    [Join3].[Description2] AS [Description2], 
    [Join3].[RankId2] AS [RankId1], 
    [Join3].[Description3] AS [Description3], 
    [Join3].[ClearanceId2] AS [ClearanceId1], 
    [Join3].[Description4] AS [Description4], 
    CASE WHEN ([Join3].[ShipId1] IS NULL) THEN CAST(NULL AS int) WHEN ([Join3].[CrewMemberId] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1], 
    CASE WHEN ([Join3].[ShipId1] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C2]
    FROM  [dbo].[Harbors] AS [Extent1]
    LEFT OUTER JOIN  (SELECT [Extent2].[ShipId] AS [ShipId1], [Extent2].[HarborId] AS [HarborId], [Extent2].[Description] AS [Description1], [Join2].[CrewMemberId], [Join2].[ShipId2], [Join2].[RankId1], [Join2].[ClearanceId1], [Join2].[Description2], [Join2].[RankId2], [Join2].[Description3], [Join2].[ClearanceId2], [Join2].[Description4]
        FROM  [dbo].[Ships] AS [Extent2]
        LEFT OUTER JOIN  (SELECT [Extent3].[CrewMemberId] AS [CrewMemberId], [Extent3].[ShipId] AS [ShipId2], [Extent3].[RankId] AS [RankId1], [Extent3].[ClearanceId] AS [ClearanceId1], [Extent3].[Description] AS [Description2], [Extent4].[RankId] AS [RankId2], [Extent4].[Description] AS [Description3], [Extent5].[ClearanceId] AS [ClearanceId2], [Extent5].[Description] AS [Description4]
            FROM   [dbo].[CrewMembers] AS [Extent3]
            INNER JOIN [dbo].[Ranks] AS [Extent4] ON [Extent3].[RankId] = [Extent4].[RankId]
            LEFT OUTER JOIN [dbo].[Clearances] AS [Extent5] ON [Extent3].[ClearanceId] = [Extent5].[ClearanceId] ) AS [Join2] ON [Extent2].[ShipId] = [Join2].[ShipId2] ) AS [Join3] ON [Extent1].[HarborId] = [Join3].[HarborId]
)  AS [Project1]
ORDER BY [Project1].[HarborId] ASC, [Project1].[C2] ASC, [Project1].[ShipId] ASC, [Project1].[C1] ASC