NotMapped特性可以应用到领域类的属性中,Code-First默认的约定,是为所有带有get,和set属性选择器的属性创建数据列。。
NotManpped特性打破了这个约定,你可以使用NotMapped特性到某个属性上面,然后Code-First就不会为这个属性就不会在数据表中创建列了。
我们看一下下面的代码:
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace EF2
{
[Table("StudentMaster",Schema="WaHaHa")]
public class Student
{
[Key]
[Column(Order=5)]
public int StudentKey1 { get; set; } [Key]
[Column(Order=6)]
public int StudentKey2 { get; set; } [MaxLength(20)]
[ConcurrencyCheck]
[Required]
[Column("SName",Order=1,TypeName="nvarchar")]
public string StudentName { get; set; } [NotMapped()]
public int? Age { get; set; } public int StandardRefId { get; set; } [ForeignKey("StandardRefId")]
public virtual Standard Standard { get; set; } }
}
注意到没有,这个表里面没有Age列。
但是如果属性,只有Get属性访问器,或者只有set属性访问器,那么Ef Code-First就不会为它创建数据列了。
请看:
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace EF2
{
[Table("StudentMaster",Schema="WaHaHa")]
public class Student
{
[Key]
[Column(Order=5)]
public int StudentKey1 { get; set; } [Key]
[Column(Order=6)]
public int StudentKey2 { get; set; } [MaxLength(20)]
[ConcurrencyCheck]
[Required]
[Column("SName",Order=1,TypeName="nvarchar")]
public string StudentName { get; set; } [NotMapped()]
public int? Age { get; set; } public int StandardRefId { get; set; } public string FirstName
{
get { return FirstName; }
} public int myAge;
public int MyAge
{
set { value = myAge; }
} [ForeignKey("StandardRefId")]
public virtual Standard Standard { get; set; } }
}
得到的数据库还是这个: