[英]EF CORE multiple properties that map to the same table
我有这个数据模型,我无法让它工作。
一个User
可以同时关联到一个Company
和多个。
但是一个Company
有多个Users
下面的图片示例: 我试图像这样在模型构建器上设置关系:
builder
.HasMany(c => c.Users)
.WithOne(u => u.CurrentAssociatedCompany)
.HasForeignKey(u => u.CurrentAssociatedCompanyId)
.IsRequired();
但我在迁移中遇到错误
值不能为空。 (参数'键')
甚至研究过 InverseProperty 但也没有运气。
我的问题是,是否有可能实现这一目标,还是应该尝试不同的方法?
从User
和Company
之间的关系,您可以设计如下所示的模型:
模型
public class User
{
public int Id { get; set; }
public string UserName { get; set; }
public int Age { get; set; }
public int CurrentAssociatedCompanyId { get; set; }
public Company CurrentAssociatedCompany { get; set; }
public ICollection<UserCompany> UserCompanies { get; set; }
}
public class Company
{
public int Id { get; set; }
public string CompanyName { get; set; }
public ICollection<UserCompany> UserCompanies { get; set; }
}
public class UserCompany
{
public int UserId { get; set; }
public User User { get; set; }
public int CompanyId { get; set; }
public Company Company { get; set; }
}
数据库上下文
public class MVCDbContext : DbContext
{
public MVCDbContext(DbContextOptions<MVCDbContext> options) : base(options)
{ }
public DbSet<User> User { get; set; }
public DbSet<Company> Company { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<UserCompany>()
.HasKey(uc => new { uc.UserId,uc.CompanyId });
modelBuilder.Entity<UserCompany>()
.HasOne(uc=>uc.Company)
.WithMany(c => c.UserCompanies)
.HasForeignKey(uc=>uc.CompanyId)
.OnDelete(DeleteBehavior.Restrict);
modelBuilder.Entity<UserCompany>()
.HasOne(uc => uc.User)
.WithMany(u => u.UserCompanies)
.HasForeignKey(uc => uc.UserId)
.OnDelete(DeleteBehavior.Restrict);
}
}
控制器
public IActionResult GetUserData(int? id)
{
var userData = _context.User
.Include(u => u.CurrentAssociatedCompany)
.Include(u => u.UserCompanies)
.ThenInclude(uc => uc.Company)
.Where(u=>u.Id==id)
.Select(u => new
{
UserId = u.Id,
UserName = u.UserName,
Age = u.Age,
CurrentAssociatedCompany = u.CurrentAssociatedCompany.CompanyName,
AssociatedCompanies = u.UserCompanies.Select(uc => new {
Id=uc.Company.Id,
CompanyName=uc.Company.CompanyName
}).ToList()
});
return Json(userData);
}
对于 EF Core 中的多对多关系,可以参考官方文档。
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