如何防止 EF Core 在实体之间进行不正确的连接

Question

我需要以某种方式明确忽略复杂类型的 "deep" 导航属性或明确告诉 EF 如何加入

我正在做一个简单的 select 用户并映射到平面视图模型（我显然已经为 ProjectTo 设置了相关映射）：

return await DataContext.Users
    .ProjectTo<UserModel>()
    .ToListAsync();

public class User {
    public int PersonId { get; set; }       
    public Person Person { get; set; }
}
public class Person {
    public int Id { get; set; }     
    public int DeptartmentId { get; set; }      
    public Department Department { get; set; }
}
public class Department {
    public int Id { get; set; }     
    public int DeptartmentHeadId { get; set; }      
    public Person DepartmentHead { get; set; }
}
public class UserSummary
{
    public Guid Id { get; set; }
    public string UserName { get; set; }
    public string Name { get; set; }
    public string DepartmentName { get; set; }
}

像这样覆盖 OnModelCreating 方法适用于这种情况，但显然会一直排除 OwnerPerson，我们只想排除当 select 从数据库中获取用户实体并将其映射到 UserModel 时：

builder.Entity<Department>().Ignore(x => x.DepartmentHead);

我需要做类似的事情：

builder.Entity<User>().Ignore(x => x.Person.Department.DepartmentHead);

使用 SQL Profiler，您可以看到它在部门上创建了一个意外的连接：

 SELECT * FROM [Users] AS [x] 
 INNER JOIN [dbo].[People] AS [x.Person]
 ON [x].[PersonId] = [x.Person].[Id] 
 LEFT JOIN [Departments] AS [x.Person.Department] 
 ON [x.Person].[Id] = [x.Person.Department].[DeptartmentHeadId]

我想要的是：

 SELECT * FROM [Users] AS [x] 
 INNER JOIN [dbo].[People] AS [x.Person]
 ON [x].[PersonId] = [x.Person].[Id] 
 LEFT JOIN [Departments] AS[x.Person.Department] 
 ON [x.Person].[DepartmentId] = [x.Person.Department].[Id]

Answer 1

我需要做的就是告诉 EF 某个部门有人（因此修复关系映射）：

public class Department {
    public int Id { get; set; }     
    public int DeptartmentHeadId { get; set; }      
    public Person DepartmentHead { get; set; }

    [InverseProperty(nameof(Person.Department))]
    public IList<Person> People { get; set; } = new List<Person>();
}

如何防止 EF Core 在实体之间进行不正确的连接

How to prevent EF Core from making an incorrect join between entities

entity-framework

entity-framework-core

entity-framework-core-2.2