0

我有以下表格和实体需要在 Fluent NHibernate 中进行映射。

表：

CREATE TABLE workarea
(
  id uuid NOT NULL,
  name character varying(255) NOT NULL,
  CONSTRAINT pk_workarea PRIMARY KEY (id),
)

CREATE TABLE element
(
  id uuid NOT NULL,
  name character varying(255) NOT NULL,
  CONSTRAINT pk_element PRIMARY KEY (id),
)

CREATE TABLE attachment
(
  id uuid NOT NULL,
  filename character varying(255) NOT NULL,
  CONSTRAINT pk_attachment PRIMARY KEY (id),
)  

CREATE TABLE objectattachment
(
  id uuid NOT NULL,
  attachmentid uuid NOT NULL,
  attachmenttype string NOT NULL,
  objectid uuid NOT NULL,
  CONSTRAINT pk_objectattachment PRIMARY KEY (id),
  CONSTRAINT fk_oa_a FOREIGN KEY (attachmentid)
      REFERENCES attachment (id) MATCH SIMPLE
      ON UPDATE RESTRICT ON DELETE RESTRICT,
  CONSTRAINT fk_oa_at FOREIGN KEY (attachmenttypeid)
      REFERENCES attachmenttype (id) MATCH SIMPLE
      ON UPDATE RESTRICT ON DELETE RESTRICT
)

这种数据库设计下的思路如下：

  • 一个“工作区”或“元素”可以有几个“附件”文件，一个“附件”文件可以由几个“工作区”或“元素”引用。

  • “工作区”或“元素”可以引用相同的“附件”文件。

所以“attachment”和“workarea”或“element”之间的关系存储在“objectattachment”表中，其中：

  • “attachmentid”字段是指特定“附件”的标识符。

  • “附件类型”字段（鉴别器）定义此关系是在“附件”和“工作区”之间还是在“附件”和“元素”之间。

  • “objectid”字段是指特定“workarea”或“element”的标识符，取决于上述“attachmenttype”字段的值。

然后根据数据库设计，定义领域模型类如下：

public class WorkArea    
{
     private Guid _id = Guid.Empty;
     private string _name;
     public virtual Guid Id     
     {
          get { return _id ; }
          set { _id = value; }
     }
     public virtual string Name     
     {
          get { return _name ; }
          set { _name = value; }
     }
}

public class Element    
{
     private Guid _id = Guid.Empty;
     private string _name;
     public virtual Guid Id     
     {
          get { return _id ; }
          set { _id = value; }
     }
     public virtual string Name     
     {
          get { return _name ; }
          set { _name = value; }
     }
}

public class Attachment
{
     private Guid _id = Guid.Empty;
     private string _fileName;
     public virtual Guid Id     
     {
          get { return _id ; }
          set { _id = value; }
     }
     public virtual string FileName     
     {
          get { return _fileName; }
          set { _fileName= value; }
     }
}

public class WorkAreaAttachment : Attachment
{
     private WorkArea _workArea;
     public virtual WorkArea WorkArea 
     {
          get { return _workArea; }
          set { _workArea = value; }
     }     
}

public class ElementAttachment : Attachment
{
     private Element _element;
     public virtual Element Element
     {
          get { return _element; }
          set { _element = value; }
     }     
}

现在我的问题是我是否可以将这些域模型类与上述数据库设计进行映射。如果是，那我该怎么做？如果不是，那么如何更改域模型类以支持针对设计数据库的 Fluent NHibernate 映射，因为我不想更改当前的数据库设计（即为“工作区”和“元素”创建单独的“附件”表） .

问候， 权

4

1 回答 1

0 
public class AttachmentLink
{
     private Attachment _attachment;
     public virtual Attachment Parent
     {
          get { return _attachment; }
          set { _attachment = value; }
     }

     private IHasAttachments _linkedTo;
     public virtual IHasAttachments LinkedTo
     {
          get { return _linkedTo; }
          set { _linkedTo = value; }
     }
}

// in AttachmentMap
HasMany(x => x.Links)
    .Table("objectattachment");

// map the component
sealed class AttachmentLinkMap : ComponentMap<AttachmentLink>
{
    public AttachmentLinkMap()
    {
        References(x => x.Attachment, "attachmentid");
        ReferencesAny(x => x.LinkedTo)
            .IdentityType<Guid>()
            .EntityIdentifierColumn("objectid")
            .EntityTypeColumn("attachmenttype")
            .AddMetaValue<WorkArea>(typeof(WorkArea).Name.ToLower())
            .AddMetaValue<Element>(typeof(Element).Name.ToLower())
            .Not.LazyLoad();  // to prevent false proxies
    }
}


// in ElementMap, and almost the same in WorkAreaMap
HasManyToMany(x => x.Attachments)
    .Where("attachmenttype='element'")

注意：链接表中不需要 Id 列

于 2012-03-01T11:34:10.537 回答