实体框架：使用代码优先方法定义关系答案

【问题标题】：Entitiy Framework: Defining relations with Code First Approach实体框架：使用代码优先方法定义关系
【发布时间】：2016-01-18 14:43:48
【问题描述】：

作为 Entity Framework 及其方法的新手，我有几个模型类，我想用它们以代码优先的方法创建数据库表。 Usermodel 的 id 指的是 2 个表，每个表至少指向 2 列，如下所示。

    public class ControlGroup
    {

        public int ControlGroupId { get; set; }

        public string ControlGroupName { get; set; }

        public virtual User CreatedBy { get; set; }

        public DateTime CreationTime { get; set; }

        public virtual User UpdatedBy { get; set; }

        public DateTime UpdateTime { get; set; }

    }

    public class ControlPoint
    {

        public int ControlPointId { get; set; }

        public string ControlPointName { get; set; }

        public virtual User CreatedBy { get; set; }

        public DateTime CreationTime { get; set; }

        public virtual User UpdatedBy { get; set; }

        public virtual User Auditor{ get; set; }

        public DateTime UpdateTime { get; set; }

    }

    public class User
    {

        public string UserId { get; set; }

        public string UserFirstName { get; set; }

        public string UserLastName { get; set; }

        public string UserPassword { get; set; }

        public string UserEmail { get; set; }

        public virtual UserType UserType { get; set; }

    }

我已经在ControlGroup 和ControlPoint 类中定义了User，但我对如何在User 类中定义关系感到困惑。我是否需要在User 中为其他两个类中的每个User 对象放置5 个属性，还是只需要一个就足够了？任何帮助将不胜感激。

【问题讨论】：

标签： database-design ef-code-first entity-framework-6 code-first

【解决方案1】：

添加到您的所有课程 ID 字段
向用户类添加导航属性
我假设您在 User 和 ControlPoint、ControlGroup 实体之间存在一对多的关系。
我从User中删除了UserType字段，因为你没有显示UserType类声明，也没有指定它们之间的关系（我不知道怎么处理，你自己解决）。

最终模型将如下所示：

public class ControlGroup
{
    //was added
    public int ID { get; set; }

    public int ControlGroupId { get; set; }    
    public string ControlGroupName { get; set; }    
    public virtual User CreatedBy { get; set; }    
    public DateTime CreationTime { get; set; }    
    public virtual User UpdatedBy { get; set; }    
    public DateTime UpdateTime { get; set; }    
}

public class ControlPoint
{
    //was added
    public int ID { get; set; }

    public int ControlPointId { get; set; }    
    public string ControlPointName { get; set; }    
    public virtual User CreatedBy { get; set; }    
    public DateTime CreationTime { get; set; }    
    public virtual User UpdatedBy { get; set; }    
    public virtual User Auditor { get; set; }    
    public DateTime UpdateTime { get; set; }    
}

public class User
{
    //was added
    public int ID { get; set; }

    public string UserId { get; set; }    
    public string UserFirstName { get; set; }    
    public string UserLastName { get; set; }    
    public string UserPassword { get; set; }    
    public string UserEmail { get; set; }

    //on your own
    //public virtual UserType UserType { get; set; }

    //navigation properties one-to-many were added
    [InverseProperty("Auditor")]
    public virtual ICollection<ControlPoint> ControlPointAuditor { get; set; }
    [InverseProperty("UpdatedBy")]
    public virtual ICollection<ControlPoint> ControlPointUpdatedBy { get; set; }
    [InverseProperty("CreatedBy")]
    public virtual ICollection<ControlPoint> ControlPointCreatedBy { get; set; }    
    [InverseProperty("UpdatedBy")]
    public virtual ICollection<ControlGroup> ControlGroupUpdatedBy { get; set; }
    [InverseProperty("CreatedBy")]
    public virtual ICollection<ControlGroup> ControlGroupCreatedBy { get; set; }
    //navigation one-to-many
}

【讨论】：