映射抽象类和子类时NHibernate的DuplicateMappingException [英] NHibernate DuplicateMappingException when mapping abstract class and subclass

问题描述

我有一个抽象类和这个的子类，我想用NHibernate把它映射到我的数据库。我正在使用Fluent，并且在wiki上阅读如何进行映射。但是当我添加子类的映射时，映射时会抛出一个NHibernate.DuplicateMappingException异常。为什么？

以下是我的（简化）类：

  public abstract class FieldValue 
 {
 public int Id {get;组; } 
 public abstract object Value {get;组; } 
} 
 
 public class StringFieldValue：FieldValue 
 {
 public string ValueAsString {get;组; } 
 public override object Value 
 {
 get 
 {
 return ValueAsString; 
} 
 set 
 {
 ValueAsString =（string）value; 
 
 
 
 
 
 
映射： p> 
 
 
  public class FieldValueMapping：ClassMap< FieldValue> 
 {
 public FieldValueMapping（）
 {
 Id（m => m.Id）.GeneratedBy.HiLo（1）; 
 // DiscriminateSubClassesOnColumn（type）; 
} 
} 
 
 public class StringValueMapping：SubclassMap< StringFieldValue> 
 {
 public StringValueMapping（）
 {
 Map（m => m.ValueAsString）.Length（100）; 
 
 
 
 
 
 
 $例外
 
 
 
 
 NHibernate.MappingException：无法编译映射文档：（XmlDocument）
 ----> NHibernate.DuplicateMappingException：重复的类/实体映射NamespacePath.StringFieldValue  
 
有什么想法？ 
解决方案
发现问题。事实证明，我在用于配置数据库的PersistenceModel中多次引用了相同的程序集： 
 
 
  public class MappingsPersistenceModel：PersistenceModel 
 {
 public MappingsPersistenceModel（）
 {
 AddMappingsFromAssembly（typeof（FooMapping）.Assembly）; 
 AddMappingsFromAssembly（typeof（BarMapping）.Assembly）; 
 // FooMapping和BarMapping在同一个程序集中。 
 
 
 
 
 $ b $ p $显然这对于​​ClassMap映射来说不是问题。但是对于SubclassMap来说，它不能很好地处理它，从而导致重复的映射，从而导致DuplicateMappingException异常。删除PersistenceModel中的重复项可以解决问题。  
I have an abstract class, and subclasses of this, and I want to map this to my database using NHibernate. I'm using Fluent, and read on the wiki how to do the mapping. But when I add the mapping of the subclass an NHibernate.DuplicateMappingException is thrown when it is mapping. Why? 

Here are my (simplified) classes: 
public abstract class FieldValue
{
    public int Id { get; set; }
    public abstract object Value { get; set; }
}

public class StringFieldValue : FieldValue
{        
    public string ValueAsString { get; set; }
    public override object Value
    {
        get
        {
            return ValueAsString; 
        } 
        set
        {
            ValueAsString = (string)value; 
        }
    } 
}
And the mappings: 
public class FieldValueMapping : ClassMap<FieldValue>
{
    public FieldValueMapping()
    {
        Id(m => m.Id).GeneratedBy.HiLo("1");
        // DiscriminateSubClassesOnColumn("type"); 
    }
}

public class StringValueMapping : SubclassMap<StringFieldValue>
{
    public StringValueMapping()
    { 
        Map(m => m.ValueAsString).Length(100);
    }
}
And the exception: 

  
NHibernate.MappingException : Could not compile the mapping document: (XmlDocument)
    ----> NHibernate.DuplicateMappingException : Duplicate class/entity mapping NamespacePath.StringFieldValue
Any ideas? 
解决方案
Discovered the problem. It turned out that I did reference the same Assembly several times in the PersistenceModel used to configure the database: 
public class MappingsPersistenceModel : PersistenceModel
{
    public MappingsPersistenceModel()
    {
        AddMappingsFromAssembly(typeof(FooMapping).Assembly);
        AddMappingsFromAssembly(typeof(BarMapping).Assembly);
        // Where FooMapping and BarMapping is in the same Assembly. 
    }
}
Apparently this is not a problem for ClassMap-mappings. But for SubclassMap it doesn't handle it as well, causing duplicate mappings - and hence the DuplicateMappingException. Removing the duplicates in the PersistenceModel fixes the problem. 

                        
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