[英]Entity Framework 4.1 Code First and One-to-Many mapping problem
I have problem with mapping existing database. 我有映射现有数据库的问题。
2 tables (simplified) 2桌(简化)
"SomeEntity"
Id int
Name nvarchar
and 和
"EntityProperty"
EntityId int
Name nvarchar
and have relation one-to-many from Entity to entity properties. 并且从实体到实体属性具有一对多的关系。
How I can map this using EF 4.1 Code First? 我如何使用EF 4.1 Code First进行映射?
Thx in advance. Thx提前。
Edited 1: 编辑1:
ok) this is my code 好的)这是我的代码
class Program
{
static void Main(string[] args)
{
var context = new DataContext();
var result = context.SomeEntity.Include(p => p.EntityProperties);
foreach (var entity in result)
{
Console.WriteLine(entity);
}
}
}
public class SomeEntity
{
public int EntityId { get; set; }
public string Name { get; set; }
public virtual ICollection<EntityProperty> EntityProperties { get; set; }
public override string ToString()
{
return string.Format("Id: {0}, Name: {1}", EntityId, Name);
}
}
public class EntityProperty
{
public int EntityId { get; set; }
public string Name { get; set; }
}
public class DataContext : DbContext
{
public DbSet<SomeEntity> SomeEntity { get { return this.Set<SomeEntity>(); } }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<SomeEntity>().ToTable("SomeEntity");
modelBuilder.Entity<SomeEntity>().HasKey(k => k.EntityId);
modelBuilder.Entity<EntityProperty>().ToTable("EntityProperty");
modelBuilder.Entity<EntityProperty>().HasKey(k => k.EntityId);
}
}
Problem when I use Include in query for get properties: 在查询获取属性时使用Include时出现问题:
Invalid column name 'SomeEntity_EntityId'. 列名称“SomeEntity_EntityId”无效。 Invalid column name 'SomeEntity_EntityId'.
列名称“SomeEntity_EntityId”无效。
public class SomeEntity
{
public int SomeEntityId {get;set;}
public string Name {get;set;}
public ICollection<EntityProperty> EntityProperties {get;set;}
}
public class EntityProperty
{
public int EntityPropertyId {get;set;}
public string Name {get;set;}
}
Creating that ICollection (at '1' side of relation) should be enough to set 1:N relation. 创建ICollection(在关系的“1”侧)应足以设置1:N关系。 It will create SomeEntity_Id (or SomeEntityId) column in EntityProperty table.
它将在EntityProperty表中创建SomeEntity_Id(或SomeEntityId)列。
Edit: Btw: You can set that collection to virtual, if you want lazy loading enabled. 编辑:顺便说一句:如果要启用延迟加载,可以将该集合设置为虚拟。
public virtual ICollection<EntityProperty> EntityProperties {get;set}
Edit: 编辑:
public class SomeEntity
{
[Key]
public int Id {get;set;}
public string Name {get;set;}
}
public class EntityProperty
{
// What is PK here? Something like:
[Key]
public int Id {get;set;}
// EntityId is FK
public int EntityId {get;set;}
// Navigation property
[ForeignKey("EntityId")]
public SomeEntity LinkedEntity {get;set;}
public string Name {get;set;}
}
First try this.. then you can add that ICollection again, I didn't include it this time to keep it simple (and you an still query properties.. but with: context.EntityProperties.Where(x=>x.EntityId == X);
) 首先尝试这个..然后你可以再次添加ICollection,这次我没有包含它以保持简单(你还是一个查询属性..但是:
context.EntityProperties.Where(x=>x.EntityId == X);
)
I solved problem. 我解决了问题。 I cannot add simple PK to relational table.
我无法向关系表添加简单的PK。 I added complex PK on all unique fields and map one-to-many.
我在所有唯一字段上添加了复杂的PK并映射了一对多。 That's all.
就这样。
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