C# 如何使用左外联接在linq中联接四个表

我想使用LINQ连接多个表。我能够联接一个表并在视图中显示结果，但是当我试图显示其余的表时，我得到了以下错误

System.InvalidOperationException:“LINQ表达式”DbSet（） .GroupJoin( 内部：DbSet（）， outerKeySelector:MachineModel=>MachineModel.EnvironmentTypeID， innerKeySelector:EnvironmentTypeModel=>EnvironmentTypeModel.EnvironmentTypeID， 结果选择器：（MachineModel，表1）=>新建{ MachineModel=MachineModel， 表1=表1 })“无法翻译。以可以翻译的形式重写查询，或者通过插入对“AsEnumerable”、“asAsAsAsyncEnumerable”、“ToList”或“ToListSync”的调用显式切换到客户端计算

[HttpGet]
        public List<JoinedMachineModel> Get()
        {
            List<JoinedMachineModel> result = (from MachineModel in _context.Machines
                          join EnvironmentTypeModel in _context.EnvironmentTypeID on MachineModel.EnvironmentTypeID equals EnvironmentTypeModel.EnvironmentTypeID into table1
                          join HighTrustEnvironmentTypeModel in _context.HighTrustEnvironmentTypes on MachineModel.HighTrustEnvironmentTypeID equals HighTrustEnvironmentTypeModel.HighTrustEnvironmentTypeID into table2
                          //join PhysicalLocationTypeModel in _context.PhysicalLocationTypes on MachineModel.PhysicalLocationTypeID equals PhysicalLocationTypeModel.PhysicalLocationTypeID into table3
                          //join OwnerTypeModel in _context.OwnerTypes on MachineModel.OwnerTypeID equals OwnerTypeModel.OwnerTypeID into table4
                          from updatedtable in table1.DefaultIfEmpty()
                          from updatedtable2 in table2.DefaultIfEmpty()
                          //from updatedtable3 in table3.DefaultIfEmpty()
                          //from updatedtable4 in table4.DefaultIfEmpty()
                          
                          orderby updatedtable2.HighTrustEnvironmentTypeID
                          
                          select new
                          {
                              machineid = (int?)MachineModel.MachineID,
                              machinename = MachineModel.MachineName,
                              machinedescription = MachineModel.MachineDescription,
                              machineidentifier = MachineModel.MachineIdentifier,
                              environmentid = (int?)updatedtable.EnvironmentTypeID,
                              //ownerid = (int?)updatedtable4.OwnerTypeID,
                              hightrustenvironmentid = (int?)updatedtable2.HighTrustEnvironmentTypeID,
                              //physicallocationid = (int?)updatedtable3.PhysicalLocationTypeID,
                              createddatetime = MachineModel.CreatedDateTime,
                              updateddatetime = MachineModel.UpdatedDateTime,
                              updatedby = MachineModel.UpdatedBy,
                              isdeleted = (bool?)MachineModel.IsDeleted,
                              environmentname = updatedtable.EnvironmentTypeName,
                              //physicallocationname = updatedtable3.PhysicalLocationTypeName,
                              hightrustname = updatedtable2.HighTrustEnvironmentTypeName,
                              //ownername = updatedtable4.OwnerTypeName
                          }).ToList()
                          .Select(x => new JoinedMachineModel()
                          {
                              MachineID = x.machineid,
                              MachineName =x.machinename,
                              MachineDescription = x.machinedescription,
                              MachineIdentifier = x.machineidentifier,
                              EnvironmentTypeID = x.environmentid,
                              //OwnerTypeID = x.ownerid,
                              HighTrustEnvironmentTypeID = x.hightrustenvironmentid,
                              //PhysicallocationTypeID = x.physicallocationid,
                              CreatedDateTime = x.createddatetime,
                              UpdatedDateTime = x.updateddatetime,
                              UpdatedBy = x.updatedby,
                              IsDeleted = x.isdeleted,
                              EnvironmentTypeName = x.environmentname,
                              //PhysicalLocationTypeName = x.physicallocationname,
                              HighTrustEnvironmentTypeName = x.hightrustname, 
                              //OwnerTypeName = x.ownername
                          }).ToList();
            return (List<JoinedMachineModel>)result;
        }

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如果您需要更多信息，请告诉我。

请参阅以下内容：重复问题。考虑一下现有的答案，如JJungYes所评论的，我找到了答案。我只是在努力确定应该对解决方案进行哪些更改以使连接正常工作。答案没有详细说明为使所有连接正常工作所做的具体操作。我需要表演一组吗。请记住，我对这方面还不太熟悉。谢谢

public class JoinedMachineModel
    {
      

        public int? MachineID { get; set; }

        public string MachineName { get; set; }

        public string MachineDescription { get; set; }

        public string MachineIdentifier { get; set; }


        [Key]

        public int? EnvironmentTypeID { get; set; }


        public int? OwnerTypeID { get; set; }

        public int? HighTrustEnvironmentTypeID { get; set; }

        public int? PhysicallocationTypeID { get; set; }

        public DateTime CreatedDateTime { get; set; }

       

        public DateTime UpdatedDateTime { get; set; }

        public string UpdatedBy { get; set; }


        public bool? IsDeleted { get; set; }




        // Joined Columns


        public string EnvironmentTypeName { get; set; }

        public string PhysicalLocationTypeName { get; set; }

        public string HighTrustEnvironmentTypeName { get; set; }

        public string OwnerTypeName { get; set; }