实体框架code首先流利的API：添加索引的列 [英] Entity Framework Code First Fluent Api: Adding Indexes to columns

问题描述

我跑EF 4.2 CF和想在我的POCO对象来创建某些列的索引。

I'm running EF 4.2 CF and want to create indexes on certain columns in my POCO objects.

作为一个例子，假设我们有这样的员工类：

As an example lets say we have this employee class:

public class Employee
{
  public int EmployeeID { get; set; }
  public string EmployeeCode { get; set; }
  public string FirstName { get; set; }
  public string LastName { get; set; }
  public DateTime HireDate { get; set; }
}

我们常常被他们的员工code做员工搜索和因为有很多的员工，这将是很好的有一个索引性能方面的原因。

We often do searches for employees by their EmployeeCode and since there are a lot of employees it would be nice to have that indexed for performance reasons.

我们能做到这一点用流利的API不知何故？或者数据注解？

Can we do this with fluent api somehow? or perhaps data annotations?

我知道这是可能执行SQL命令是这样的：

I know it is possible to execute sql commands something like this:

context.Database.ExecuteSqlCommand("CREATE INDEX IX_NAME ON ...");

我非常希望避免这样的原始的SQL。

I would very much like to avoid raw SQL like that.

我知道这并不存在，但在寻找类似的规定：

i know this does not exist but looking for something along those lines:

class EmployeeConfiguration : EntityTypeConfiguration<Employee>
    {
        internal EmployeeConfiguration()
        {
            this.HasIndex(e => e.EmployeeCode)
                .HasIndex(e => e.FirstName)
                .HasIndex(e => e.LastName);
        }
    }

或者使用 System.ComponentModel.DataAnnotations 的POCO看起来是这样的（再次我知道这不存在）：

or maybe using System.ComponentModel.DataAnnotations the POCO could look like this (again i know this does not exist):

public class Employee
{
  public int EmployeeID { get; set; }
  [Indexed]
  public string EmployeeCode { get; set; }
  [Indexed]
  public string FirstName { get; set; }
  [Indexed]
  public string LastName { get; set; }
  public DateTime HireDate { get; set; }
}

人对如何做到这一点的任何想法，或者有实施办法做到这一点任何计划时，code第一种方式？

Anyone have any ideas on how to do this, or if there are any plans to implement a way to do this, the code first way?

更新：作为由罗巴的答复中提到，此功能在EF版本中实现6.1

UPDATE: As mentioned in the answer by Robba, this feature is implemented in EF version 6.1

推荐答案

迁移后，在EF 4.3引入了修改或创建一个表时，你现在可以添加索引。下面是从<一个摘录href=\"http://blogs.msdn.com/b/adonet/archive/2012/02/09/ef-4-3-$c$c-based-migrations-walkthrough.aspx\">EF 4.3 $ C $基于C语言迁移演练从ADO.NET团队博客

After Migrations was introduced in EF 4.3 you can now add indexes when modifying or creating a table. Here is an excerpt from the EF 4.3 Code-Based Migrations Walkthrough from the ADO.NET team blog

namespace MigrationsCodeDemo.Migrations
{
    using System.Data.Entity.Migrations;

    public partial class AddPostClass : DbMigration
    {
        public override void Up()
        {
            CreateTable(
                "Posts",
                c => new
                    {
                        PostId = c.Int(nullable: false, identity: true),
                        Title = c.String(maxLength: 200),
                        Content = c.String(),
                        BlogId = c.Int(nullable: false),
                    })
                .PrimaryKey(t => t.PostId)
                .ForeignKey("Blogs", t => t.BlogId, cascadeDelete: true)
                .Index(t => t.BlogId)
                .Index(p => p.Title, unique: true);

            AddColumn("Blogs", "Rating", c => c.Int(nullable: false, defaultValue: 3));
        }

        public override void Down()
        {
            DropIndex("Posts", new[] { "BlogId" });
            DropForeignKey("Posts", "BlogId", "Blogs");
            DropColumn("Blogs", "Rating");
            DropTable("Posts");
        }
    }
}

这是一个很好的强类型的方法来添加索引，这是我一直在寻找，当我第一次张贴的问题。

This is a nice strongly typed way to add the indexes, which was what i was looking for when i first posted the question.

这篇关于实体框架code首先流利的API：添加索引的列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！