EF Core Identity - Applicationuser 与返回 null 的另一个实体具有一对一关系答案

【问题标题】：EF Core Identity - Applicationuser with one-to-one relationship with another entity returning nullEF Core Identity - Applicationuser 与返回 null 的另一个实体具有一对一关系
【发布时间】：2021-04-20 01:18:17
【问题描述】：

我与 ApplicationUser 有以下一对一的关系：

public class Person
    {
        public Guid PersonId { get; set; }
        public string UserId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Company { get; set; }
        public string Role { get; set; }
        public string Country { get; set; }
        public DateTime CreatedDate { get; set; }
        public bool IsActive { get; set; }

        public ApplicationUser User { get; set; }
   }

public class ApplicationUser : IdentityUser
    {
        public Guid PersonId { get; set; }
        public string Provider { get; set; } = "LOCAL";
        public string ExternalUserId { get; set; }

        public Person Person { get; set; }
    }

数据库上下文：

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> opts) : base(opts) { }

        public DbSet<Person> Person { get; set; }        
        public DbSet<ApplicationUser> User { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            modelBuilder.ApplyConfiguration(new PersonConfiguration());  
                                    
            modelBuilder.Entity<ApplicationUser>(e => {
                e.ToTable(name: "User");
                e.HasOne(p => p.Person).WithOne(u => u.User);
                //e.HasOne(p => p.Person).WithOne().HasForeignKey;
            });
            modelBuilder.Entity<IdentityRole>(e => e.ToTable(name: "Role"));
            modelBuilder.Entity<IdentityUserRole<string>>(e => e.ToTable(name: "UserRole"));
            modelBuilder.Entity<IdentityUserClaim<string>>(e => e.ToTable(name: "UserClaim"));
            modelBuilder.Entity<IdentityUserLogin<string>>(e => e.ToTable(name: "UserLogin"));
            modelBuilder.Entity<IdentityUserToken<string>>(e => e.ToTable(name: "UserToken"));
            modelBuilder.Entity<IdentityRoleClaim<string>>(e => e.ToTable(name: "RoleClaim"));           
             
        }
    }

人物实体配置：

public class PersonConfiguration : IEntityTypeConfiguration<Person>
    {
        public void Configure(EntityTypeBuilder<Person> builder)
        {
            builder.ToTable("Person");

            builder.HasOne(u => u.User)
                   .WithOne(p => p.Person)
                   .HasForeignKey<Person>(p => p.UserId);
         }
    }

问题是当我从 db 获取人员数据时，即使使用 Include 扩展，相关用户也会返回 null。仅供参考：我尝试使用 dbcontext 从 db 加载用户，但它也返回 null。

【问题讨论】：

尝试将virtual 添加到public Person Person { get; set; }。有关更多信息，请阅读此答案stackoverflow.com/questions/41881169/…

标签： c# asp.net-core entity-framework-core asp.net-identity

【解决方案1】：

我测试了你的代码，我认为你的配置没有问题，所以问题可能是你的数据插入造成的。你可以尝试添加一个新的Person，然后尝试如下找到它们：

  var user = new ApplicationUser
        {
            Email = "www.example.com"
        };
        var p = new Person
        {
            FirstName = "AA",
            //...
            User = user,  
        };
        _context.Persons.Add(p);
        _context.SaveChanges();

        var u =  _context.User.ToList();
        var pe = _context.Persons.Include(c => c.User).ToList();

【讨论】：