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etienne
 Post subject: Composite key and loading example needed
PostPosted: Mon Jul 11, 2005 11:47 am 
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Senior

Joined: Tue Jan 11, 2005 5:03 pm
Posts: 137
Location: Montreal, Quebec
HI,

I have check around in the forum and in the hibernate doc, and I didn't found a simple example of retrieving a record with a composite key.

I have this mapping:

Code:
<class name="ExchangeRate"
         table="ExchangeRate"
           mutable="false">
           
    <composite-id name="id" class="ExchangeRateId">
      <key-property name="Currency" type="TrimmedString">
        <column name="Currency" scale="3" precision="0" not-null="true" sql-type="char" />
      </key-property>
      <key-property name="RateDate" type="Numeric8DigitToDateFormat">
        <column name="RateDate" scale="8" precision="0" not-null="true" sql-type="numeric" />
      </key-property>
    </composite-id>
   
    <property name="Rate" type="java.math.BigDecimal">
      <column name="Rate" scale="13" precision="7" not-null="true" sql-type="decimal" />
    </property>
(-- more properties here... --)
</class>



I would like to know what is the "one liner code" (simpliest code) for my DAO method "getExchangeRateByIDs(currency, date)".

I need to use it for retrieving a record by the composite primary key. Can I use the session.load()? but I dont have the "Primary key" of the composite-key class (ExchangeRateId).

Should I use a Criteria? Could I have an exemple please? I would prefer not to use HQL here...

Thanks all

Etienne
Montreal
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etienne
 Post subject:
PostPosted: Mon Jul 11, 2005 1:43 pm 
Senior
Senior

Joined: Tue Jan 11, 2005 5:03 pm
Posts: 137
Location: Montreal, Quebec
Hi,

I think I have manage to make it work with the simpliest code:

In my DAO:

Code:
   public ExchangeRate findExchangeRateByIds(String exchangeRateCurrencyCode, Date exchangeRateDate) {
      Session session = SessionFactoryUtils.getSession(getSessionFactory(), true);
      Criteria criteria = session.createCriteria(ExchangeRate.class);
      criteria.add(Expression.eq("id.currency", exchangeRateCurrencyCode));
      criteria.add(Expression.eq("id.rateDate", exchangeRateDate));
      return (ExchangeRate)criteria.uniqueResult();
   }


Can it be more simplier?

Thanks.

Etienne.
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