fluent nhibernate - 具有属性的多对多映射 [英] fluent nhibernate - Many to Many mapping with attribute

问题描述

我有 2 个主表，它们由一个映射表链接，如下所示

I have 2 master tables which are linked by a map table as below

User [UserId,Name]

Resource [ResourceId,Name]

UserResourceMap [UserId,ResourceId,AccessLevel]

将 AccessLevel 作为资源属性的 Resource 和 User ClassMap 看起来如何?

How would the Resource and User ClassMap with AccessLevel as a resource attribute look?

My Domain 类看起来像这样

My Domain classes look like this

public class User
{
    public virtual int UserId { get;protected set; }
    public virtual string Name { get;set; }
}
public class Resource
{
    public virtual int ResourceId { get;protected set; }
    public virtual string Name { get;set; }
    public virtual string AccessLevel { get;set; }//Issue-populate this using fluent
}

如何使用 fluent 映射以下代码中的 accessLevel 属性.

How can I use fluent to map the accessLevel attribute in the below code.

public class UserMap : ClassMap<User>
    {
        public UserMap()
        {
            Table("User");
            Id(x => x.Key);
            Map(x=>x.Name);
        }
    }

public class ResourceMap : ClassMap<Resource>
    {
        public ResourceMap()
        {
            Table("Resource");
            Id(x => x.Key);
            Map(x=>x.Name);//Need some Map Here to make a hasManyToMany Map with attribute
        }
    }

推荐答案

您的域模型似乎与您的数据库模型不匹配 - Resource 类具有属性 AccessLevel(即每个资源一个 AccessLevel)但在 DB 模型中 AccessLevel 是映射表上的一列(即每个用户-资源关系一个访问级别).

Your domain model does not seem to match your database model - the Resource class has the property AccessLevel (i.e. one AccessLevel per Resource) but in the DB model AccessLevel is a column on the map table (i.e. one AccessLevel per User-Resource relation).

假设 DB 模型是正确的模型，一种(相当简单的)映射方法就是引入这样的类.

Assuming the DB model is the correct model one (fairly straightforward) way of mapping this would be to introduce a class like this.

public class UserResource {

  public virtual int UserResourceId { get; protected set; }
  public virtual User User { get; set; }
  public virtual Resource { get; set; }
  public virtual string AccessLevel { get; set; }
}

并以这种方式映射:

public class UserResourceMap : ClassMap<UserResource> {

  public UserResourceMap() {

    Table("UserResourceMap");
    Id(x => x.UserResourceId);
    References(x => x.User).UniqueKey("UniqueUserAndResource");
    References(x => x.Resource).UniqueKey("UniqueUserAndResource");
    Map(x => x.AccessLevel);
  }
}

如果您想要双向关联，您还可以在 User 和/或 Resource 上添加 Collection 属性，并使用 HasMany(...).Inverse() 映射它们.当然，这种映射会在 UserResourceMap 表中引入一个新的 UserResourceId 列(使用由 User 和 Resource 组成的复合键可以缓解这种情况).

If you want bidirectional associations you could also add a Collection property on User and/or Resource and map these with HasMany(...).Inverse(). Of course, this kind of mapping would introduce a new UserResourceId column in the UserResourceMap table (using a composite key consisting of User and Resource would mitigate that).

另一种解决方案是添加 EntityMap 关联.如果关联归用户所有，它将是 Dictionary 属性.像这样的事情可能会奏效:

Another solution would be to add an EntityMap association. If the association is owned by User it would be a Dictionary<Resource, string> property. Something like this might do the trick:

public class User {
  public virtual int UserId { get; protected set; }
  public virtual string Name { get; set; }
  public virtual Dictionary<Resource, string> Resources { get; set; } // Resource -> AccessLevel
}

public class UserMap : ClassMap<User> {

  public UserMap() {

    Table("User");
    Id(x => x.UserId);
    Map(x => x.Name);
    HasMany<Resource, string>(x => x.Resources).AsEntityMap().Element("AccessLevel");
  }
}

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