Fluent NHibernate：一对多映射到抽象类中存在外键的子类

Question

我是 NHibernate/Fluent NHibernate 的新手，我正在尝试弄清楚如何将它与现有的数据库结构一起使用。如果可能的话，我想让它在不改变数据库结构的情况下工作。

我尝试松散映射的数据库结构类似于：

Forms
----
FormId
CompletedBy

Records
-------
RecordId
RecordTypeId
FormId

EducationRecords
----------------
RecordId
SchoolName
DateAttendedFrom
DateAttendedTo

我的实体：

public class Form
{
    public virtual int Id { get; private set; }
    public virtual string CompletedBy { get; set; }

    public virtual IList<Entities.EducationRecord> EducationRecords { get; set; }

    public Form()
    {
        this.EducationRecords = new List<EducationRecord>();
    }
}

public abstract class Record
{
    public virtual int Id { get; set; }
    public virtual int RecordTypeId { get; set; }
    public virtual Form Parent { get; set; }
}

public class EducationRecord : Record
{
    public virtual string SchoolName { get; set; }
    public virtual DateTime DateAttendedFrom { get; set; }
    public virtual DateTime DateAttendedTo { get; set; }
}

我的映射：

public class FormMap : ClassMap<Entities.Form>
{
    public FormMap()
    {
        Table("Forms");
        Id(x => x.Id, "FormId");
        Map(x => x.CompletedBy);

        HasMany(x => x.EducationRecords);
    }
}

public class RecordMap : ClassMap<Entities.Record>
{
    public RecordMap()
    {

        Table("Records");
        Id(x => x.Id, "RecordId");
        Map(x => x.RecordTypeId);
        References(x => x.Parent, "FormId");
    }
}

public class EducationRecordMap : SubclassMap<Entities.EducationRecord>
{
    public EducationRecordMap()
    {
        Table("EducationRecords");
        KeyColumn("RecordId");
        Map(x => x.SchoolName);
        Map(x => x.DateAttendedFrom);
        Map(x => x.DateAttendedTo);
    }
}

按照当前的设置方式，在尝试访问 Form 的 EducationRecords 属性时出现以下异常：

[SqlException (0x80131904): Invalid column name 'FormId'.
Invalid column name 'FormId'.]

看起来底层 SQL 查询正在尝试查询 EducationRecords 表中的“FormId”列，但该列不存在。我花了很多时间尝试使用我的地图类配置的不同变体，但没有运气。

所以我的问题是：如何告诉 Fluent NHibernate 在检索教育记录时使用记录表中的“FormId”列，或者这是否可能？

---

Update:
My problem seems to essentially be the same as the one stated here (which, unfortunately, the question was never resolved):
Fluent NHibernate inheritance mapping problem

---

Update 2:

按照建议，我对 FormMap 进行了以下更改：

HasMany(x => x.EducationRecords).Inverse();

但仍然出现同样的问题。

这是源错误：

Line 14: 
Line 15:     <div>
Line 16:         <% if (Model.EducationRecords.Any()) { %>
Line 17: 
Line 18:             <table>

模型的类型为表单。

以下是堆栈跟踪：

[SqlException (0x80131904): Invalid column name 'FormId'.
Invalid column name 'FormId'.]
   System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) +2030802
   System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +5009584
   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() +234
   System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +2275
   System.Data.SqlClient.SqlDataReader.ConsumeMetaData() +33
   System.Data.SqlClient.SqlDataReader.get_MetaData() +86
   System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) +311
   System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) +987
   System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) +162
   System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) +32
   System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) +141
   System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) +12
   System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader() +12
   NHibernate.AdoNet.AbstractBatcher.ExecuteReader(IDbCommand cmd) +278
   NHibernate.Loader.Loader.GetResultSet(IDbCommand st, Boolean autoDiscoverTypes, Boolean callable, RowSelection selection, ISessionImplementor session) +264
   NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +186
   NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +70
   NHibernate.Loader.Loader.LoadCollection(ISessionImplementor session, Object id, IType type) +226

[GenericADOException: could not initialize a collection: [Sample.NHibernate.Entities.Form.EducationRecords#1][SQL: SELECT educationr0_.FormId as FormId1_, educationr0_.RecordId as RecordId1_, educationr0_.RecordId as RecordId1_0_, educationr0_1_.RecordTypeId as RecordTy2_1_0_, educationr0_1_.FormId as FormId1_0_, educationr0_.SchoolName as SchoolName2_0_, educationr0_.DateAttendedFrom as DateAtte3_2_0_, educationr0_.DateAttendedTo as DateAtte4_2_0_, educationr0_.Degree as Degree2_0_, educationr0_.DateDegreeAwarded as DateDegr6_2_0_ FROM dbo.EducationRecords educationr0_ inner join dbo.Records educationr0_1_ on educationr0_.RecordId=educationr0_1_.RecordId WHERE educationr0_.FormId=?]]
   NHibernate.Loader.Loader.LoadCollection(ISessionImplementor session, Object id, IType type) +345
   NHibernate.Loader.Collection.CollectionLoader.Initialize(Object id, ISessionImplementor session) +27
   NHibernate.Persister.Collection.AbstractCollectionPersister.Initialize(Object key, ISessionImplementor session) +29
   NHibernate.Event.Default.DefaultInitializeCollectionEventListener.OnInitializeCollection(InitializeCollectionEvent event) +349
   NHibernate.Impl.SessionImpl.InitializeCollection(IPersistentCollection collection, Boolean writing) +431
   NHibernate.Collection.AbstractPersistentCollection.Initialize(Boolean writing) +47
   NHibernate.Collection.Generic.PersistentGenericBag`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() +16
   System.Linq.Enumerable.Any(IEnumerable`1 source) +71
   ASP.views_form_index_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer) in c:\Dev\Sandbox\NHibernateSample\Sample.Web\Views\Form\Index.aspx:16
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +109
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +8
   System.Web.UI.Control.Render(HtmlTextWriter writer) +10
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +100
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +208
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +8
   System.Web.UI.Control.Render(HtmlTextWriter writer) +10
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +100
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +208
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +8
   System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer) +55
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +100
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3060

在 GenericADOException 中显示的生成的 SQL 查询中，WHERE 子句指定：

WHERE educationr0_.FormId=?

但它需要是：

WHERE educationr0_1_.FormId=?

Answer 1

我花了一段时间才重新审视这一点。在发布这个问题后不久，我就停止使用 Fluent NHibernate。

回想起来，我认为我想要完成的事情可能存在根本性的错误。只需将 EducationRecords 列表替换为 Records 即可解决我的问题。如果需要，可以从中检索特定类型的记录。

我不记得为什么我最初认为我需要 Forms 中的 EducationRecords 列表。我怀疑这要么是我对 ORM 缺乏经验，要么是数据库设计中存在未正确表示的约束。

Answer 2

解决方案确实非常简单。您需要为所有子类映射指定，这是一个抽象
基类

public class EducationRecordMap : SubclassMap<Entities.EducationRecord>
{
   public EducationRecordMap()
   {
    Table("EducationRecords");

    Abstract(); // because Record base class is abstract

    KeyColumn("RecordId");
    Map(x => x.SchoolName);
    Map(x => x.DateAttendedFrom);
    Map(x => x.DateAttendedTo);
  }
 }

Answer 3

尝试改变：

HasMany(x => x.EducationRecords);

通过

HasMany(x => x.EducationRecords).Inverse();

这种方式，你告诉NH，只有这段关系中的孩子负责储蓄。

您可以在此处阅读有关多余更新的更多信息：
http://nhprof.com/Learn/Alerts/SuperfluousManyToOneUpdate

Answer 4

您应该检查生成的 XML 映射。也许它生成子类映射而不是连接子类。
http://knol.google.com /k/fabio-maulo/nhibernate-chapter-8-inheritance-mapping/1nr4enxv3dpeq/11

Answer 5

尝试这个映射：

public class FormMap : ClassMap<Entities.Form>
{
    public FormMap()
    {
        Table("Forms");
        Id(x => x.Id, "FormId");
        Map(x => x.CompletedBy);

        HasMany<Record>(x => x.EducationRecords).Where("form0_1_.EducationRecordId is not null");
    }
}

并使类 Record 不再抽象。这对我有用。也许“form0_1_”不是正确的列名称。您可以在生成的 SQL 中找到正确的 SQL。