如何在EF Core 2.1中定义外键关系 [英] How to define foreign key relationship in EF Core 2.1

问题描述

我的DAL使用的是EF Core 2.1。这就是我的模型的样子

一个用户只能拥有一个角色：

  //角色实体-主角色的类型
 public class Role 
 {
 public int RoleId {get;组; } 
 
公用字符串RoleName {get;组; } 
} 
 
 //用户实体-每个用户将有一个角色
公共类User 
 {
 public int UserId {get;组; } 
 
公用字符串电子邮件{get;组; } 
公用字符串密码{get;组; } 
 
 public int RoleId {get;组; } 
 public bool IsActive {get;组; } 
 public DateTime CreatedOn {get;组; } 
 
公共虚拟角色Role {组; } 
} 
  

这就是我想/试图定义两者之间的关系的方式实体：

  public void Configure（EntityTypeBuilder< User>生成器）
 {
 builder.HasKey（x => x.UserId）; 
 builder.Property（x => x.RoleId）.IsRequired（true）; 
 builder.Property（x => x.CreatedOn）.IsRequired（true）.HasDefaultValue（DateTime.Now）; 
 
 // FK-抛出编译时错误
 builder.HasOne（x => x.Role）.WithOne（y => y.RoleId）; 
} 
  

如何使用EF Fluent API定义此一个用户一个角色关系？ / p>

谢谢。

附件：-

解决方案

不仅在FK关系配置中，对于 CreatedOn 列。因此，请按以下方式编写您的实体配置：

  public void Configure（EntityTypeBuilder< User> builder）
 {
 builder.HasKey（u => u.UserId）; 
 builder.Property（u => u.CreatedOn）.IsRequired（true）.HasDefaultValueSql（ getdate（））; 
 
 // FK-配置
 builder.HasOne（u => u.Role）.WithMany（）。HasForeignKey（u => u.RoleId）.IsRequired（true）; 
} 
  

I am using EF Core 2.1 for my DAL. This is how my model looks like

One user can have only one role:

// Role entity - kind of master
public class Role
{
    public int RoleId { get; set; }

    public string RoleName { get; set; }
}

// User entity - every user will have one role
public class User
{
    public int UserId { get; set; }

    public string Email { get; set; }
    public string Password { get; set; }

    public int RoleId { get; set; }
    public bool IsActive { get; set; }
    public DateTime CreatedOn { get; set; }

    public virtual Role Role { get; set; }
}

This is how I was thinking/tried to define the relationship between these two entities:

public void Configure(EntityTypeBuilder<User> builder)
{
    builder.HasKey(x => x.UserId);
    builder.Property(x => x.RoleId).IsRequired(true);
    builder.Property(x => x.CreatedOn).IsRequired(true).HasDefaultValue(DateTime.Now);

    // FK - throwing compile time error 
    builder.HasOne(x => x.Role).WithOne(y => y.RoleId);
}

How do I define this one user one role relation using EF Fluent API?

Thanks.

Attachment:-

解决方案

Not only in the FK relationship configuration, you also have problem in the default value generation configuration for the CreatedOn column. So write your Entity Configuration as follows:

public void Configure(EntityTypeBuilder<User> builder)
{
    builder.HasKey(u => u.UserId);
    builder.Property(u => u.CreatedOn).IsRequired(true).HasDefaultValueSql("getdate()");

    // FK - configuraiton
    builder.HasOne(u => u.Role).WithMany().HasForeignKey(u => u.RoleId).IsRequired(true);
}

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