Data Annotation Feature-NotMapped, Annotation Feature-notmapped

Data Annotation Feature-NotMapped, Annotation Feature-notmapped

The NotMapped feature can be applied to the attributes of the domain class. The default Code-First Convention creates data columns for all attributes with get, and set attribute selectors ..

The NotManpped feature breaks this Convention. You can use the NotMapped feature to add a property. Then Code-First will not create columns for this property in the data table.

Let's take a look at the following code:

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; }          }}

 

Note: No. The table does not contain the Age column.

However, if only the Get attribute accessors or the set attribute accessors are available, Ef Code-First will not create data columns for them.

See:

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; }          }}

The obtained database is still like this: