Entity Framework Code First需要实现Repository模式吗

2025-03-17 00:22:31
推荐回答(1个)
回答1:

Entity Framework Code First属性映射约定中“约定”一词,在原文版中为“Convention”,翻译成约定或许有些不好理解,这也是网上比较大多数的翻译,我们就当这是Entity Framework的一些使用“规则”,这样或许更好理解一些。

  Entity Framework Code First与数据表之间的映射方式有两种实现:Data Annotation和Fluent API。本文中采用创建Product类为例来说明tity Framework Code First属性映射约定的具体方式。

  1、表名及所有者

  在默认约定的情况下,Entity Framework Code First创建的表名是根据类名的英语复数形式,创建的表所有者为dbo,可以通过重写约定来指定表名及表的所有者。

  1>、Data Annotation方式

  在使用Data Annotation方式进行Entity Framework Code First与数据库映射之前,需要先添加命名空间引用。

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using System.ComponentModel.DataAnnotations.Schema;

  为类配置对应表名:

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[Table("Product")]
public class Product

  为类配置对应表名并指定表的所有者:

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[Table("Product", Schema = "dbo")]
public class Product

  2>、Fluent API方式

  Fluent API实现配置Entity Framework Code First与数据库映射关系主要是通过继承DbContext并重写其中的OnModelCreating方法来进行的。在本文中新建类文件PortalContext.cs继承DbContext。

  在继承DbContext之前,添加命名空间引用。

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using System.Data.Entity;

  重写OnModelCreating方法,配置类对应于数据库中的表名:

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protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity().ToTable("Product");
}

  重写OnModelCreating方法,配置类对应于数据库中的表名,并指定表的所有者:

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protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity().ToTable("Product", "dbo");
}

  到此处PortalContext.cs的完整代码:

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Data.Entity;

using Portal.Entities;

namespace Portal
{
public class PortalContext : DbContext
{
static PortalContext()
{
Database.SetInitializer(new DropCreateDatabaseIfModelChanges());
}

public PortalContext()
: base("name=PortalContext")
{
}

public DbSet Products { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity().ToTable("Product", "dbo");
}
}
}

2、字段名、长度、数据类型及是否可空

  在默认约定的情况下,Entity Framework Code First创建的列名与类的属性名相同,可以根据需要进行重新指定类属性与列名之间的映射关系。

  1>、Data Annotation方式

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