How to use <component> with NHibernate.Mapping.Attribu

-daV (guest) · **Posted:** Wed Aug 17, 2005 10:35 am

Hi All,

Several of my classes (and tables) contain a validity information (beginDate and endDate fields of "dateTime" type).

I'm trying to implement a <component> containing this info and that could be reused in each class. I'm defining the mapping with mapping attributes in my classes.

As I'm quite a newbie on Nhibernate, my first question is : Is it the correct way to handle that kind of problems?

I'd like to get this kind of hbm file but through mapping attributes :

Code:

<component name="ValidityPeriod" class="ValidityPeriod">
    <property name="BeginDate" access="field" />
    <property name="EndDate" access="field" />
</component>

The [component] attribute is a class attribute, then I implemented by ValidityPeriod class like :

Code:

   [Component(Name="ValidityPeriod")]
   public class ValidityPeriod
   {
      private static DateTime INFINITE = new DateTime(9999,12,31);

      public DateTime _begin;
      public DateTime _end; // never null

      public DateTime Begin
      {
         get
         {
            return _begin;
         }
         set
         {
            _begin = value;
         }
      }

      public XsDateTime End
      {
         get
         {
            if (_end == INFINITE)
            {
               return XsDateTime.Null;
            }
            else
            {
               return _end;
            }
         }
         set
         {
            if (value.IsNull)
            {
               _end = INFINITE;
            }
            else
            {
               _end = value;
            }
         }
      }

Is the attribute [component] correctly defined?

What is the attribute I can use to create a property using that component?

Thanks !!

-daV

KPixel · **Posted:** Fri Aug 19, 2005 8:39 am

Hi,

Your situation is a good usage case of <component>.

As <component> must be in a <*class>, your Component class must also be in a mapped class.

Here is an example showing what you can do to share a component with many classes:

Code:

// DON'T MAP THIS CLASS
public class ValidityPeriod
{
   [Property]
   public DateTime Begin { ... }
   [Property]
   public DateTime End { ... }
}

[Class]
public class Entity1
{
   [Component]
   private class Entity1ValidityPeriod : ValidityPeriod {}
   // Here, Entity1ValidityPeriod will inherit properties of ValidityPeriod
}

-daV · **Posted:** Tue Aug 23, 2005 9:19 am

Thank you, it helps me a lot.

The [component] do not seem to be inheritable such as typical properties. Is it normal? or is there a problem in my implementation?

Thx,

KPixel · **Posted:** Wed Aug 24, 2005 8:52 am

-daV wrote:

The [component] do not seem to be inheritable such as typical properties. Is it normal? or is there a problem in my implementation?

Class-level attributes are not inherited; that's a design choice...