Entity Framework Fluent API and Indexing

最新推荐文章于 2022-03-06 21:45:25 发布

suzhi921

最新推荐文章于 2022-03-06 21:45:25 发布

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分类专栏： LINQ

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本文介绍如何使用Entity Framework (EF) 的 Fluent API 来为 People 实体类的不同属性定义单列索引、多列索引、唯一索引及聚集索引，并讨论了当前版本 EF 中尚不支持的功能。

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public class People  
{
    public int Id { get; set; }
    public string Firstname { get; set; }
    public string Lastname { get; set; }
    public string PhoneNumber { get; set; }
    public string NationalInsuranceNo { get; set; }
}

Single column Indexes

modelBuilder.Entity<People>()  
    .Property(x => x.Firstname)
    .HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute("ix_people_firstname")));

Multi Column Indexes

modelBuilder.Entity<People>()  
    .Property(x => x.Firstname)
    .HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute("ix_people_fullname", 1)));
modelBuilder.Entity<People>()  
    .Property(x => x.Lastname)
    .HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute("ix_people_fullname", 2)));

Unique Indexes

modelBuilder.Entity<People>()  
    .Property(x => x.NationalInsuranceNo)
    .HasColumnAnnotation("Index",
        new IndexAnnotation(new IndexAttribute("ix_people_nationalinsurance") {IsUnique = true}));

Clustered Indexes

modelBuilder.Entity<People>()  
    .Property(x => x.Id)
    .HasColumnAnnotation("Index",
        new IndexAnnotation(new IndexAttribute("ix_people_nationalinsurance") { IsClustered = true}));

What's Not Possible Using Fluent API

As of Entity Framework 6.1.1

Include Fields
Sort Order (ASC,DESC)
Filtered Indexes

Whilst this is a big step forwards it still feels like a work in progress. I would hope to end up with a friendlier and more complete syntax for doing this something like...