用Fluent NHibernate自動映射創建多個雙向一對多關聯

Question

我對NHibernate和.NET框架相當新穎。

我想映射我的Project類，它具有一對多關係Subproject和ProjectTask類。

public class Project : ProjectItem 
{ 
    public virtual IList<Subproject> Subprojects { get; set; } 

    public virtual IList<ProjectTask> Tasks { get; set; } 

    [NotNull] 
    public virtual ProjectStatus Status { get; set; } 

    public Project() 
    { 
     Subprojects = new List<Subproject>(); 
     Tasks = new List<ProjectTask>(); 
     Status = new ProjectStatus(); 
    } 

    public virtual void AddSubProject(Subproject subproject) 
    { 
     subproject.Project = this; 
     Subprojects.Add(subproject); 
    } 

    public virtual void RemoveSubProject(Subproject subproject) 
    { 
     Subprojects.Remove(subproject); 
    } 

    public virtual void AddTask(ProjectTask task) 
    { 
     task.Project = this; 
     Tasks.Add(task); 
    } 

    public virtual void RemoveTask(ProjectTask task) 
    { 
     Tasks.Remove(task); 
    } 
} 

public class ProjectTask : ProjectItemTask 
{ 
    [NotNull] 
    public virtual Project Project { get; set; } 
} 

public class Subproject : ProjectItem 
{ 
    [NotNull] 
    public virtual Project Project { get; set; } 
} 

我的實體繼承了抽象基類的Id屬性。

我用自動映射到覆蓋重新定義我的映射：

public class ProjectMappingOverride : IAutoMappingOverride<Project> 
{ 
    public void Override(AutoMapping<Project> mapping) 
    { 
     mapping.HasMany<Subproject>(x => x.Subprojects) 
      .Cascade.All() 
      .Inverse() 
      .Not.LazyLoad() 
      .AsBag(); 

     mapping.HasMany<ProjectTask>(x => x.Tasks) 
      .Cascade.All() 
      .Inverse() 
      .Not.LazyLoad() 
      .AsBag(); 

     mapping.HasOne<ProjectStatus>(x => x.Status) 
      .Cascade.All() 
      .Not.LazyLoad(); 
    } 
} 

public class SubprojectMappingOverride : IAutoMappingOverride<Subproject> 
{ 
    public void Override(AutoMapping<Subproject> mapping) 
    { 
     mapping.References<Project>(x => x.Project) 
      .ForeignKey("ProjectId"); 
    } 
} 

public class ProjectTaskMappingOverride : IAutoMappingOverride<ProjectTask> 
{ 
    public void Override(AutoMapping<ProjectTask> mapping) 
    { 
     mapping.References<Project>(x => x.Project) 
      .ForeignKey("ProjectId"); 
    } 
} 

當我只用映射子項目課堂上的一切協會工作正常，在Project.Subprojects子項目類的所有實例都將被存儲到數據庫正確。當我使用ProjectTask類的第二個覆蓋時，出現以下異常：

---> NHibernate.HibernateException：數據庫中已有一個名爲'ProjectId'的對象。無法創建約束。查看以前的錯誤。

---> System.Data.SqlClient.SqlException：數據庫中已經有一個名爲'ProjectId'的對象。

有誰知道，爲什麼會發生這種情況？

Answer 1

你應該用Column而不是ForeignKey

mapping.References<Project>(x => x.Project) 
      .Column("ProjectId");