[英]The expression 'y.Cases' is invalid inside an 'Include' operation
I have one-to-many relationship database.我有一对多的关系数据库。 DbSet Companies
being "One" and DbSet Cases
being "many". DbSet Companies
是“一个”,而 DbSet Cases
是“许多”。 Here's my context and model classes:这是我的上下文和 model 类:
Database Context数据库上下文
class CaseContext : DbContext
{
public DbSet<ParticipantCompany> Companies{ get; set; }
public DbSet<ParticipantPerson> Persons { get; set; }
public DbSet<LegalCase> Cases { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder options)
=> options.UseSqlite("Data Source=Clients.db");
}
ParticipantCompany
class inherits from Participant
Class. ParticipantCompany
class 继承自Participant
Class。
public class ParticipantCompany : Participant
{
public ParticipantCompany():this(false, "","","","") { }
public ParticipantCompany (bool isclient) : this(isclient, "","","","") { }
public ParticipantCompany(bool isclient, string name, string address, string inncompany, string ogrn) : base(isclient, SubjectType.Company)
{
Name = name;
Address = address;
InnCompany = inncompany;
Ogrn = ogrn;
}
public string InnCompany { get; set; }
public string Ogrn { get; set; }
}
public abstract class Participant
{
public Participant(bool isclient, SubjectType Type, string name, string address)
{
SubjType = Type;
IsClient = isclient;
Name = name;
Address = address;
}
public Participant(bool isclient, SubjectType Type ) : this(isclient, Type, "","")
{
}
public int Id { get; set; }
public SubjectType SubjType { get; private set; }
public bool IsClient { get; set; }
public string Name { get; set; }
public string Address { get; set; }
public List<LegalCase> Cases = new List<LegalCase>();
}
LegalCase
class represents "Many" in relationships LegalCase
class 代表关系中的“许多”
public class LegalCase
{
public LegalCase() : this("", CaseType.ArbGeneral){}
public LegalCase(string casefabula, CaseType casetype)
{
CaseFabula = casefabula;
CaseType = casetype;
}
public int Id { get; set; }
public string CaseFabula { get; set; }
public CaseType CaseType { get; set; }
//public ICaseParticipant Client { get; set; }
public int? CompanyId { get; set; }
public ParticipantCompany Company { get; set; }
public int? PersonId { get; set; }
public ParticipantPerson Person { get; set; }
}
Now here's the Query:现在这里是查询:
using(var db = new CaseContext())
{
var QClients = db.Companies
.Where(x => x.IsClient == true)
//Exception: The expression 'y.Cases' is
// invalid inside an 'Include' operation,
// since it does not represent a property
// access: 't => t.MyProperty'. etc
.Include(y => y.Cases)
.ToList();
}
I tried to explicitly cast y
to ParticipantCompany
since it's what the prompt of the exection seems to suggest:我试图将y
显式转换为ParticipantCompany
,因为这似乎是执行提示所暗示的:
To target navigations declared on derived types, use casting ('t => ((Derived)t).MyProperty') or the 'as' operator ('t => (t as Derived).MyProperty')要定位在派生类型上声明的导航,请使用强制转换 ('t => ((Derived)t).MyProperty') 或 'as' 运算符 ('t => (t as Derived).MyProperty')
But it generates the same exception:但它会产生相同的异常:
using(var db = new CaseContext())
{
var QClients = db.Companies
.Where(x => x.IsClient == true)
//Same exception
.Include(y => (y as ParticipantCompany).Cases)
.ToList();
}
Change Cases
from being field to property as the exception suggests:例外情况表明,将Cases
从字段更改为属性:
public List<LegalCase> Cases { get; set; } = new List<LegalCase>();
Each entity type in your model has a set of properties, which EF Core will read and write from the database. model 中的每个实体类型都有一组属性,EF Core 将从数据库中读取和写入这些属性。 If you're using a relational database, entity properties map to table columns.如果您使用的是关系数据库,则将实体属性 map 转换为表列。
By convention, all public properties with a getter and a setter will be included in the model.按照惯例,所有带有 getter 和 setter 的公共属性都将包含在 model 中。
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