忽略 Entity Framework 4.1 Code First 中的类属性 [英] Ignoring a class property in Entity Framework 4.1 Code First

问题描述

我的理解是 [NotMapped] 属性直到 EF 5 才可用，它目前在 CTP 中，所以我们不能在生产中使用它.

My understanding is that the [NotMapped] attribute is not available until EF 5 which is currently in CTP so we cannot use it in production.

如何将 EF 4.1 中的属性标记为忽略?

How can I mark properties in EF 4.1 to be ignored?

更新:我注意到了一些奇怪的事情.我让 [NotMapped] 属性起作用，但由于某种原因，EF 4.1 仍然在数据库中创建一个名为 Disposed 的列，即使 public bool Disposed { get;私人订制；} 用[NotMapped] 标记.该类当然实现了 IDisposeable，但我不知道这有什么关系.有什么想法吗?

UPDATE: I noticed something else strange. I got the [NotMapped] attribute to work but for some reason, EF 4.1 still creates a column named Disposed in the database even though the public bool Disposed { get; private set; } is marked with [NotMapped]. The class implements IDisposeable of course but I don't see how that should matter. Any thoughts?

推荐答案

您可以使用 NotMapped 属性数据注释来指示 Code-First 排除特定属性

You can use the NotMapped attribute data annotation to instruct Code-First to exclude a particular property

public class Customer
{
    public int CustomerID { set; get; }
    public string FirstName { set; get; } 
    public string LastName{ set; get; } 
    [NotMapped]
    public int Age { set; get; }
}

[NotMapped] 属性包含在 System.ComponentModel.DataAnnotations 命名空间中.

[NotMapped] attribute is included in the System.ComponentModel.DataAnnotations namespace.

您也可以使用 Fluent API 覆盖 DBContext 类中的 OnModelCreating 函数来执行此操作:

You can alternatively do this with Fluent API overriding OnModelCreating function in your DBContext class:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
   modelBuilder.Entity<Customer>().Ignore(t => t.LastName);
   base.OnModelCreating(modelBuilder);
}

http://msdn.microsoft.com/en-us/library/hh295847(v=vs.103).aspx

我检查的版本是EF 4.3，这是使用NuGet时可用的最新稳定版本.

The version I checked is EF 4.3, which is the latest stable version available when you use NuGet.

编辑:2017 年 9 月

数据标注

如果您使用的是 asp.net core(在撰写本文时为 2.0)，则可以在属性级别使用 [NotMapped] 属性.

If you are using asp.net core (2.0 at the time of this writing), The [NotMapped] attribute can be used on the property level.

public class Customer
{
    public int Id { set; get; }
    public string FirstName { set; get; } 
    public string LastName { set; get; } 
    [NotMapped]
    public int FullName { set; get; }
}

流畅的 API

public class SchoolContext : DbContext
{
    public SchoolContext(DbContextOptions<SchoolContext> options) : base(options)
    {
    }
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>().Ignore(t => t.FullName);
        base.OnModelCreating(modelBuilder);
    }
    public DbSet<Customer> Customers { get; set; }
}

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