kob*_*490 181 c# entity-framework entity-framework-6 ef-fluent-api
我正在尝试使用Code First构建一个EF实体,并EntityTypeConfiguration
使用流畅的API.使用Unique Constraint创建主键很容易,但不是这样.我看到旧帖子建议为此执行本机SQL命令,但这似乎打败了目的.这可能与EF6有关吗?
Yor*_*rro 267
在EF6.2上,您可以使用HasIndex()
通过Fluent API添加用于迁移的索引.
https://github.com/aspnet/EntityFramework6/issues/274
例
modelBuilder
.Entity<User>()
.HasIndex(u => u.Email)
.IsUnique();
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在EF6.1以后,您可以使用IndexAnnotation()
在流畅的API中添加迁移索引.
http://msdn.microsoft.com/en-us/data/jj591617.aspx#PropertyIndex
您必须添加以下参考:
using System.Data.Entity.Infrastructure.Annotations;
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基本例子
这是一个简单的用法,在User.FirstName
属性上添加索引
modelBuilder
.Entity<User>()
.Property(t => t.FirstName)
.HasColumnAnnotation(IndexAnnotation.AnnotationName, new IndexAnnotation(new IndexAttribute()));
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实际例子:
这是一个更现实的例子.它在多个属性上添加了唯一索引:User.FirstName
并且User.LastName
索引名称为"IX_FIrstNameLastName"
modelBuilder
.Entity<User>()
.Property(t => t.FirstName)
.IsRequired()
.HasMaxLength(60)
.HasColumnAnnotation(
IndexAnnotation.AnnotationName,
new IndexAnnotation(
new IndexAttribute("IX_FirstNameLastName", 1) { IsUnique = true }));
modelBuilder
.Entity<User>()
.Property(t => t.LastName)
.IsRequired()
.HasMaxLength(60)
.HasColumnAnnotation(
IndexAnnotation.AnnotationName,
new IndexAnnotation(
new IndexAttribute("IX_FirstNameLastName", 2) { IsUnique = true }));
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con*_*i2k 134
作为Yorro答案的补充,它也可以通过使用属性来完成.
int
类型唯一键组合的示例:
[Index("IX_UniqueKeyInt", IsUnique = true, Order = 1)]
public int UniqueKeyIntPart1 { get; set; }
[Index("IX_UniqueKeyInt", IsUnique = true, Order = 2)]
public int UniqueKeyIntPart2 { get; set; }
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如果数据类型是string
,则MaxLength
必须添加属性:
[Index("IX_UniqueKeyString", IsUnique = true, Order = 1)]
[MaxLength(50)]
public string UniqueKeyStringPart1 { get; set; }
[Index("IX_UniqueKeyString", IsUnique = true, Order = 2)]
[MaxLength(50)]
public string UniqueKeyStringPart2 { get; set; }
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如果存在域/存储模型分离问题,使用Metadatatype
属性/类可以是一个选项:https://msdn.microsoft.com/en-us/library/ff664465%28v =pandp.50%29.aspx?f = 255&MSPPError = -2147217396
快速控制台应用示例:
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;
namespace EFIndexTest
{
class Program
{
static void Main(string[] args)
{
using (var context = new AppDbContext())
{
var newUser = new User { UniqueKeyIntPart1 = 1, UniqueKeyIntPart2 = 1, UniqueKeyStringPart1 = "A", UniqueKeyStringPart2 = "A" };
context.UserSet.Add(newUser);
context.SaveChanges();
}
}
}
[MetadataType(typeof(UserMetadata))]
public class User
{
public int Id { get; set; }
public int UniqueKeyIntPart1 { get; set; }
public int UniqueKeyIntPart2 { get; set; }
public string UniqueKeyStringPart1 { get; set; }
public string UniqueKeyStringPart2 { get; set; }
}
public class UserMetadata
{
[Index("IX_UniqueKeyInt", IsUnique = true, Order = 1)]
public int UniqueKeyIntPart1 { get; set; }
[Index("IX_UniqueKeyInt", IsUnique = true, Order = 2)]
public int UniqueKeyIntPart2 { get; set; }
[Index("IX_UniqueKeyString", IsUnique = true, Order = 1)]
[MaxLength(50)]
public string UniqueKeyStringPart1 { get; set; }
[Index("IX_UniqueKeyString", IsUnique = true, Order = 2)]
[MaxLength(50)]
public string UniqueKeyStringPart2 { get; set; }
}
public class AppDbContext : DbContext
{
public virtual DbSet<User> UserSet { get; set; }
}
}
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Bar*_*ann 17
这是一个更流利地设置唯一索引的扩展方法:
public static class MappingExtensions
{
public static PrimitivePropertyConfiguration IsUnique(this PrimitivePropertyConfiguration configuration)
{
return configuration.HasColumnAnnotation("Index", new IndexAnnotation(new IndexAttribute { IsUnique = true }));
}
}
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用法:
modelBuilder
.Entity<Person>()
.Property(t => t.Name)
.IsUnique();
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将生成迁移,例如:
public partial class Add_unique_index : DbMigration
{
public override void Up()
{
CreateIndex("dbo.Person", "Name", unique: true);
}
public override void Down()
{
DropIndex("dbo.Person", new[] { "Name" });
}
}
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Src:使用Entity Framework 6.1创建唯一索引流畅的API
Ari*_*oon 16
@ coni2k的答案是正确的,但你必须[StringLength]
为它添加属性才能工作,否则你将得到一个无效的密钥异常(例如下面的例子).
[StringLength(65)]
[Index("IX_FirstNameLastName", 1, IsUnique = true)]
public string FirstName { get; set; }
[StringLength(65)]
[Index("IX_FirstNameLastName", 2, IsUnique = true)]
public string LastName { get; set; }
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