映射nhibernate父母/子女关系的“其他”方式 [英] mapping nhibernate parent/child relationship the 'other' way round

问题描述

使用FluentNhibernate;

我试图坚持一个看似简单的对象模型：

  public class Product 
 {
 public int Id {get;组; } 
 public string Name {get;组; } 
 public Config {{get;组; } 
} 
 
 public class Config 
 {
 public int ConfigId {get;组; } 
 public int ProductId {get;组; } 
 public string ConfigField1 {get;组; } 
 public string ConfigField2 {get;组;这个数据库看起来像：（在语法上不正确）
  > 
  

$ p $ CREATE TABLE [dbo]。[Products]（
[ProductId] [int] IDENTITY（1,1）NOT NULL，
[Name] [varchar]（50）NULL
）

创建表[dbo]。[Config]（
[ConfigId] [int] IDENTITY（1， 1）NOT NULL，
[ProductId] [int] NOT NULL，
[ConfigField1] [varchar]（50）NULL，
[ConfigField2] [varchar]（50）NULL
）ON [PRIMARY]


开箱即用的fluent-nhibernate会尝试将其映射为外部键 Products 表，例如：
$ b

INSERT INTO Products（Name，Config_id ）VALUES（？，？）;

我不希望它这样做，而是希望映射先插入产品，然后再插入 ProductId 被插入到配置表中。

我把我的头发拉出来，尝试覆盖和阅读链接，如这个和，但仍然不能做到我想要的。我正在使用现有的数据和代码，所以我宁愿不更改数据库表定义或域对象。还有一点比这个例子所描绘的要多，所以如果我们可以避免讨论领域模型设计，那将是非常棒的。我有一个这个项目的链接这里（假设数据库存在）

我目前的流利映射是：

  public class ProductOverrides：IAutoMappingOverride< Product> 
 public void Override（AutoMapping< Product> mapping）
 {
 mapping.Id（x => x.Id）.Column（ProductId）; 
 mapping.Table（Products）; 
} 
} 
 
 public class ConfigOverrides：IAutoMappingOverride< Config> 
 {
 public void Override（AutoMapping< Config> mapping）
 {
 mapping.Id（x => x.ConfigId）; 
 
 
 
 $ div $解析方案

正试图通过映射多方的两倍来映射一对一的关系作为一对多的关系。这是行不通的。 NHibernate在它的一对一的定义是严格的，并要求双方都有相同的主键，所以也不会工作。

我有<在这之前，我就碰到了这个问题，并找到了最好的解决方法是将其建模为一个标准的多对多，但是只允许通过封装对该对象的访问来允许集合中的一个项目。在你的情况下，我会猜测产品将是一方，并配置许多。

using FluentNhibernate;

I am trying to persist a seemingly simple object model:

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Config Config { get; set; }
}

public class Config
{
    public int ConfigId { get; set; }
    public int ProductId { get; set; }
    public string ConfigField1 { get; set; }
    public string ConfigField2 { get; set; }
}

and the database looks like: (not syntactically correct)

CREATE TABLE [dbo].[Products](
[ProductId] [int] IDENTITY(1,1) NOT NULL,
[Name] [varchar](50) NULL
)

CREATE TABLE [dbo].[Config](
[ConfigId] [int] IDENTITY(1,1) NOT NULL,
[ProductId] [int] NOT NULL,
[ConfigField1] [varchar](50) NULL,
[ConfigField2] [varchar](50) NULL
) ON [PRIMARY]

Out of the box fluent-nhibernate will try and map this as a foreign key on the Products table, eg:

INSERT INTO Products (Name, Config_id) VALUES (?, ?);

I don't want it to do this, rather I was hoping the mapping would insert Products first then the config second with ProductId being inserted into the Config table.

I've pulled my hair out trying overrides and reading links such as this and this but still can't get it to do what I want. I am working with existing data and code so I would rather not change the database table definitions or the domain object. There is a bit more going on than what this example paints so if we could avoid discussions on domain model design that would be great. I have a link to a spike of this project here (assumes database exists)

my current fluent mappings are:

public class ProductOverrides : IAutoMappingOverride<Product>
{
    public void Override(AutoMapping<Product> mapping)
    {
        mapping.Id(x => x.Id).Column("ProductId");            
        mapping.Table("Products");
    }
}

public class ConfigOverrides : IAutoMappingOverride<Config>
{
    public void Override(AutoMapping<Config> mapping)
    {
        mapping.Id(x => x.ConfigId);
    }
}

解决方案

You are trying to map a one-to-one relationship as a one-to-many by mapping what would be the many side twice. That won't work. NHibernate is strict in its definition of one-to-one and requires that both sides have the same primary key, so that won't work either.

I've butted heads with this before and the best workaround I found is to model it as a standard on-to-many but only allow one item in the collection by encapsulating access to the it. In your case I would guess that Product would be the one side and Config the many.

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