Dictionary of components where key is a property of cmpnt?

laevus · **Posted:** Mon Mar 26, 2007 5:15 am

Hibernate version: 1.2.0.CR1

Is it possible to map a generic dictionary of value objects (composite-elements) where the key is a property from the composite-element?

This is the mapping for the dictionary:

Code:

   <map name="Values" table="CurrencyPrice" cascade="all-delete-orphan" access="nosetter.camelcase-underscore">
      <key column="PriceId" />

      <index-many-to-many column="CurrencyId" class="MyApplication.Domain.Currency, MyApplication.Domain" />

      <composite-element class="MyApplication.Domain.Money, MyApplication.Domain">
         <property
            name="Amount"
            column="Value"
            type="Decimal"
            access="nosetter.camelcase-underscore" />
         <many-to-one
            name="Currency"
            column="CurrencyId"
            class="MyApplication.Domain.Currency, MyApplication.Domain"
            access="nosetter.camelcase-underscore"
            not-null="true" />
      </composite-element>
   </map>

As you can see, I'm using the column CurrencyId twice - as the dictionary's key and as a property of the composite-element "Money".
I get the following NHibernate.MappingException when building the SessionFactory:

Quote:

Repeated column in mapping for collection: MyApplication.Domain.Price.Values column: CurrencyId

Type: NHibernate.MappingException
Source: NHibernate
TargetSite: Void CheckColumnDuplication(Iesi.Collections.ISet, System.Collections.ICollection)
HelpLink: null
Stack: at NHibernate.Persister.Collection.AbstractCollectionPersister.CheckColumnDuplication(ISet distinctColumns, ICollection columns)
...

Mapping documents:

Price.hbm.xml

Code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-cascade="save-update">
   <class name="MyApplication.Domain.Price, MyApplication.Domain" table="Price" lazy="true">
      <id name="Id" column="Id" type="Int32" unsaved-value="0" access="nosetter.camelcase-underscore">
         <generator class="identity" />
      </id>

      <map name="Values" table="CurrencyPrice" cascade="all-delete-orphan" access="nosetter.camelcase-underscore">
         <key column="PriceId" />

         <index-many-to-many column="CurrencyId" class="MyApplication.Domain.Currency, MyApplication.Domain" />

         <composite-element class="MyApplication.Domain.Money, MyApplication.Domain">
            <property
               name="Amount"
               column="Value"
               type="Decimal"
               access="nosetter.camelcase-underscore" />
            <many-to-one
               name="Currency"
               column="CurrencyId"
               class="MyApplication.Domain.Currency, MyApplication.Domain"
               access="nosetter.camelcase-underscore"
               not-null="true" />
         </composite-element>
      </map>

      <!-- SNIP -->
   </class>
</hibernate-mapping>

Currency.hbm.xml

Code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-cascade="save-update">
   <class name="MyApplication.Domain.Currency, MyApplication.Domain" table="Currency" lazy="true">
      <id name="Id" column="Id" type="Int32" unsaved-value="0" access="nosetter.camelcase-underscore">
         <generator class="identity" />
      </id>

      <property
         name="Code"
         column="CurrencyCode"
         type="String"
         access="nosetter.camelcase-underscore"
         not-null="true" />

      <!-- SNIP -->
   </class>
</hibernate-mapping>

Domain objects:

Value object "Money":

Code:

struct Money {
   decimal Amount { get; }
   Currency Currency { get; }
}

Entity "Currency":

Code:

class Currency {
   int Id { get; }
   string Code { get; } // "EUR", "USD" etc.
   // ...
}

The Price object holds prices for a product in different currencies. To make it easy to get the price of a product in a given currency, I would like to have a dictionary of the

prices:

Code:

class Price {
   Dictionary<Currency, Money> Values { get; }
}

laevus · **Posted:** Mon Mar 26, 2007 9:20 am

I've now circumvented the problem by mapping a decimal (as an element) instead of the Money as a composite-element, so now I have an IDictionary<Currency, decimal> instead of IDictionary<Currency, Money>:

Code:

class Price {
   IDictionary<Currency, decimal> Values { get; }

   public virtual Money GetValue(Currency currency) {
      return new Money(currency, Values[currency]);
   }
}

This is definitely not the way I want to keep it, but it'll have to do for now.

YNight · **Joined:** Tue Mar 20, 2007 11:48 am **Posts:** 11

I'm having the same problem, searched on the net but didn't find any solution, any help would be appreciated...

mnichols · **Joined:** Mon Aug 21, 2006 9:18 am **Posts:** 179

The cause for this is simple...you can't have two columns with the same name in a table. So you need to change one of the 'column name' attributes to a different value. For example, I use the suff '_idx' for column names that are the indices for lists,etc...So it would become this...

Code:

 <map name="Values" table="CurrencyPrice" cascade="all-delete-orphan" access="nosetter.camelcase-underscore">
      <key column="PriceId" />

      <index-many-to-many column="CurrencyId_idx" class="MyApplication.Domain.Currency, MyApplication.Domain" />

      <composite-element class="MyApplication.Domain.Money, MyApplication.Domain">
         <property
            name="Amount"
            column="Value"
            type="Decimal"
            access="nosetter.camelcase-underscore" />
         <many-to-one
            name="Currency"
            column="CurrencyId"
            class="MyApplication.Domain.Currency, MyApplication.Domain"
            access="nosetter.camelcase-underscore"
            not-null="true" />
      </composite-element>
   </map>

Notice I change the following element with my _idx suffix:

Code:

<index-many-to-many column="CurrencyId_idx" class="MyApplication.Domain.Currency, MyApplication.Domain" />

Hope this helps...

laevus · **Posted:** Thu Mar 29, 2007 10:55 am

thanks, it's working now! It also seems that cascade="all-delete-orphan" does not work on a composite-element collection. I get a MappingException with the message "collection was not an association" when trying to save the owner of the collection (i.e. the price).

mnichols · **Joined:** Mon Aug 21, 2006 9:18 am **Posts:** 179

Glad it worked. You are correct about the all-delete-orphan on a component....I've gotten bit by that one more than once :)
Take care
MIKE