实体框架代码第一个通用数据库审计字段

我是Entity Framework的新手,过去我直接使用Enterprise Library或ADO.NET将模型映射到数据库表.我使用的一种模式是将我的公共审计字段放在基类中的每个表中,然后为每个对象继承该基类.

我采取两个步骤来保护两个字段(Created,CreatedBy):

在Base Enitity上创建一个无参数构造函数私有,并创建第二个需要Created和CreatedBy的构造函数在创建时传递.

使setter Private,以便在创建对象后无法更改值.

基类:

using System;

namespace App.Model
{
    [Serializable()]
    public abstract class BaseEntity
    {
        public bool IsActive { get; private set; }
        public DateTimeOffset Created { get; private set; }
        public string CreatedBy { get; private set; }
        public DateTimeOffset LastUpdated { get; protected set; }
        public string LastUpdatedBy { get; protected set; }

        private BaseEntity() { }

        protected BaseEntity(DateTimeOffset created, string createdBy)
        {
            IsActive = true;
            Created = created;
            CreatedBy = createdBy;
            LastUpdated = created;
            LastUpdatedBy = createdBy;
        }
    }
}

继承类:

using System;

namespace App.Model
{
    [Serializable()]
    public class Person : BaseEntity
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Email { get; set; }

        public Person(DateTimeOffset created, string createdBy) : 
            base(created, createdBy) {  }
    }
}

我遇到了两个问题.EF需要无参数构造函数来创建对象.EF不会创建具有私有setter的数据库列.

我的问题是,如果有更好的方法来实现我的EF目标:

要求在实例化时填充Created和CreatedBy的值.

无法更改Created和CreatedBy的值.

Gert Arnold.. 5

您可以使用接受字符串的构造函数实例化上下文createdBy.然后在覆盖SaveChanges():

public override int SaveChanges()
{
    foreach( var entity in ChangeTracker.Entries()
                                        .Where(e => e.State == EntityState.Added)
                                        .Select (e => e.Entity)
                                        .OfType())
    {
        entity.SetAuditValues(DateTimeOffset.Now, this.CreatedBy);
    }
    return base.SaveChanges();
}

与SetAuditValues()作为

internal void SetAuditValues(DateTimeOffset created, string createdBy)
{
    if (this.Created == DateTimeOffset.MinValue) this.Created = created;
    if (string.IsNullOrEmpty(this.CreatedBy)) this.CreatedBy = createdBy;
}

从数据库实现实体后,当有人调用时,不会覆盖这些值SetAuditValues.

您可以使用接受字符串的构造函数实例化上下文createdBy.然后在覆盖SaveChanges():

public override int SaveChanges()
{
    foreach( var entity in ChangeTracker.Entries()
                                        .Where(e => e.State == EntityState.Added)
                                        .Select (e => e.Entity)
                                        .OfType())
    {
        entity.SetAuditValues(DateTimeOffset.Now, this.CreatedBy);
    }
    return base.SaveChanges();
}

与SetAuditValues()作为

internal void SetAuditValues(DateTimeOffset created, string createdBy)
{
    if (this.Created == DateTimeOffset.MinValue) this.Created = created;
    if (string.IsNullOrEmpty(this.CreatedBy)) this.CreatedBy = createdBy;
}

从数据库实现实体后,当有人调用时,不会覆盖这些值SetAuditValues.