急切加载仅出现在某些结果中答案

【问题标题】：Eager loading only appear in some result急切加载仅出现在某些结果中
【发布时间】：2020-08-01 06:16:34
【问题描述】：

我目前正在使用 .Net Core 3.0，并且正在构建 Web API。我正在尝试将一些相关数据加载到前端。

我有以下类和 dbcontext 设置。

    public class EntityCommon
    {
        public int Id { get; set; }
        public DateTime CreatedDatetime { get; set; }
    }

    public class UserAmountClaim: EntityCommon
    {
        public int UserId { get; set; }
        public AmountClaimType Type { get; set; }
        public int Amount{ get; set; }
        public int? RefereeId { get; set; }
        public AmountClaimStatus Status { get; set; }
        public DateTime? ClaimedDatetime { get; set; }

        [NotMapped]
        public virtual User Referee { get; set; }
    }

    public class User : EntityCommon
    {

        public string Name { get; set; }
        public string Password { get; set; }
        public UserStatus Status { get; set; }


        [NotMapped]
        public virtual UserAmountClaim UserAmountClaim { get; set; }
    }

数据库上下文

modelbuilder.Entity<UserAmountClaim>().ToTable("UserAmountClaim ", "dbo");
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.UserId).HasColumnName("fkUserId");
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.RefereeId).HasColumnName("fkRefereeId");
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.Type).HasConversion(new EnumToStringConverter<UserAmountClaim>());
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.CreatedDatetime).ValueGeneratedOnAdd();
modelbuilder.Entity<UserAmountClaim>().HasOne(ucc => ucc.Referee).WithOne(user => user.UserAmountClaim);

Startup.cs

services.AddControllers().AddNewtonsoftJson(options =>
{
    options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
    options.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
    options.SerializerSettings.Converters.Add(new IsoDateTimeConverter { DateTimeFormat = "yyyy-MM-ddTHH:mm:ss" });
    options.SerializerSettings.Converters.Add(new StringEnumConverter());
    options.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;
});

还有如下数据

Id  fkUserId    Type                Amount fkRefereeId  Status  ClaimedDateTime  CreatedDatetime
52  1           ReferralCommission  100    2            6       NULL             2020-04-18 15:19:34.203
53  1           ReferralCommission  100    2            6       NULL             2020-04-18 15:19:40.343
54  1           ReferralCommission  100    1            6       NULL             2020-04-18 15:36:44.017
55  1           ReferralCommission  100    1            6       NULL             2020-04-18 15:51:31.757

但是当我执行以下代码时

var result = _dbContext.UserAmountClaim.Where(x => x.UserId == userId &&
                            x.Status == AmountClaimStatus.PendingUser &&
                            x.Type == AmountClaimType.ReferralCommission)
                            .Include(x => x.Referee)
                            .ToListAsync();

第一项和第三项缺少裁判


{
    "userId": 1,
    "type": "ReferralCommission",
    "amount": 100,
    "status": "PendingUser",
    "id": 52,
    "createdDatetime": "2020-04-18T15:19:34"
},
{
    "userId": 1,
    "type": "ReferralCommission",
    "amount": 100,
    "refereeId": 2,
    "status": "PendingUser",
    "referee": {
        "id": 2,
        "name": "82109380918",
        "password": "",
        "status": "Valid",
        "createdDatetime": "2020-04-16T17:45:31",
    },
    "id": 53,
    "createdDatetime": "2020-04-18T15:19:40"
},
{
    "userId": 1,
    "type": "ReferralCommission",
    "credit": 100,
    "status": "PendingUser",
    "id": 54,
    "createdDatetime": "2020-04-18T15:36:44"
},
{
    "userId": 1,
    "type": "ReferralCommission",
    "amount": 100,
    "refereeId": 1,
    "status": "PendingUser",
    "referee": {
        "id": 1,
        "name": "31829389031",
        "password": "",
        "status": "Valid",
        "createdDatetime": "2020-04-16T17:45:31",
    },
    "id": 54,
    "createdDatetime": "2020-04-18T15:36:44"
}

这种情况发生在其他具有类似结构的地方。

谁能告诉我是什么原因造成的以及如何解决这个问题？

【问题讨论】：

为什么会有这些[NotMapped] 属性？
您的fkRefereeId 列包含重复项，因此关系不是一对一的。
@GertArnold 这听起来可能很傻，但我想强调一下，它将把它排除在数据库映射之外，同时提醒自己或将来维护的人。
@IvanStoev 非常感谢！它在修改 dbcontext 关系和 User 类中的属性后起作用。我几乎忘记了一对一的关系是如何运作的！再次，非常感谢！

标签： .net-core entity-framework-core eager-loading .net-core-3.0 webapi

【解决方案1】：

正如@IvanStoev 指出的那样，设置关系和属性类是错误的

修改以下内容对我有用。

public class User : EntityCommon
{
     public string Name { get; set; }
     public string Password { get; set; }
     public UserStatus Status { get; set; }
     [NotMapped]
     public virtual List<UserAmountClaim> UserAmountClaim { get; set; }
}

数据库上下文

modelbuilder.Entity<UserAmountClaim>().ToTable("UserAmountClaim ", "dbo");
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.UserId).HasColumnName("fkUserId");
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.RefereeId).HasColumnName("fkRefereeId");
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.Type).HasConversion(new EnumToStringConverter<UserAmountClaim>());
modelbuilder.Entity<UserAmountClaim>().Property(ucc => ucc.CreatedDatetime).ValueGeneratedOnAdd();
modelbuilder.Entity<UserAmountClaim>().HasOne(ucc => ucc.Referee).WithMany(user => user.UserAmountClaim);

非常感谢@IvanStoev

【讨论】：