Question

我正在使用EF6，我在所有者和小工具之间有1：N的关系。我似乎无法获得相关的所有者信息。

public partial class Owners
{
    public Owners()
    {
        Widgets = new HashSet<Widgets>();
    }
    public int Id { get; set; }
    public string OwnerName { get; set; }
    public virtual ICollection<Widgets> Widgets { get; set; }
}

public partial class Widgets
{
    public int id { get; set; }
    public int OwnerId { get; set; }
    public string WidgetName { get; set; }
    public string WidgetType { get; set; }
    public virtual Owners Owners { get; set; }
}

public partial class Model1 : DbContext
{
    public Model1(): base("name=Model1"){}
    public virtual DbSet<Owners> Owners { get; set; }
    public virtual DbSet<Widgets> Widgets { get; set; }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Owners>()
            .HasMany(e => e.Widgets)
            .WithRequired(e => e.Owners)
            .HasForeignKey(e => e.OwnerId)
            .WillCascadeOnDelete(false);
    }
}

问题是当我运行以下查询时，我只获取Widgets的信息对业主来说没什么。如果我将生成的SQL拉出并在数据库中运行它，我将获得所有信息和相关实体信息？
我相信我在这里忽略了一些简单的事情。

using (var db = new Model1())
{
    var rslt = db.Widgets.Include(y => y.Owners);
    var rslt2 = await rslt.Where(s => s.WidgetType == "Garthug").ToListAsync();
    return rslt2;
}

这是EF生成的SQL语句，它创建并显示我在数据库中运行时所寻找的所有正确信息。（我手动输入但它应该是正确的）

SELECT 
Widgets.id AS id, 
Widgets.OwnerId AS OwnerId, 
Widgets.WidgetName AS WidgetName, 
Widgets.WidgetsType AS WidgetType, 
Owners.Id AS Id1, 
Owners.OwnerName AS OwnerName
FROM  [dbo].Widgets AS Widgets
INNER JOIN [dbo].Owners AS Owner ON Widgets.OwnerId = Owners.Id
WHERE Widgets.WidgetType = 'Garthug'

看来除了Asp身份表之外，我的设置对于每个表都是正确的......有谁知道为什么？

Answer 1

Widgets.OwnerId与Owner.Id相关联，因此类型相同

但是.NET和数据库之间的排序顺序和相等性并不一定相同。因此，您可能在数据库和EF之间存在整理冲突，其中Widget.OwnerId在数据库的排序规则中匹配Owner.Id，但在.NET的字符串比较规则中不匹配。

EG

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ef62test
{
    class Program
    {

        public partial class Owner
        {
            public string Id { get; set; }
            public string OwnerName { get; set; }
            public virtual ICollection<Widget> Widgets { get; } = new HashSet<Widget>();

        }

        public partial class Widget
        {
            public int id { get; set; }
            public string OwnerId { get; set; }
            public string WidgetName { get; set; }
            public string WidgetType { get; set; }
            public virtual Owner Owners { get; set; }
        }

        public partial class Model1 : DbContext
        {

            public virtual DbSet<Owner> Owners { get; set; }
            public virtual DbSet<Widget> Widgets { get; set; }
            protected override void OnModelCreating(DbModelBuilder modelBuilder)
            {
                modelBuilder.Entity<Owner>()
                    .HasMany(e => e.Widgets)
                    .WithRequired(e => e.Owners)
                    .HasForeignKey(e => e.OwnerId)
                    .WillCascadeOnDelete(false);
            }
        }
        static void Main(string[] args)
        {
            Database.SetInitializer(new DropCreateDatabaseAlways<Model1>());

            string ownerId = "owner1";
            using (var db = new Model1())
            {
                db.Database.Log = s => Console.WriteLine(s);
                var o = new Owner() { Id = ownerId };

                db.Owners.Add(o);

                for (int i = 0; i < 10; i++)
                {
                    o.Widgets.Add(new Widget());
                }
                db.SaveChanges();
                ownerId = o.Id;

                db.Database.ExecuteSqlCommand("update widgets set ownerId = UPPER(ownerId);");
            }

            using (var db = new Model1())
            {
                db.Database.Log = s => Console.WriteLine(s);
                db.Configuration.LazyLoadingEnabled = false;

                var owner = db.Owners.Include(o => o.Widgets).Where(o => o.Id == ownerId).First();

                Console.WriteLine(owner.Widgets.Count());
            }

            Console.WriteLine("Hit any key to exit.");
            Console.ReadKey();
        }
    }
}

Answer 2

如果是aspnetusers表，它是否与其他表存在于同一个上下文中？这可以解释为什么即使数据库没有，EF也在苦苦挣扎？

IQueryable不返回关联数据

2 个答案: