Accessing other columns in UserType impl

mmcgovern · **Posted:** Wed Jul 12, 2006 6:46 pm

I need a variation on the classic MonetaryUserType (that uses two columns: one with amount, the other with currency).

I have a legacy system with ONE currency column in the table, being the default for all amounts. I can't map the same column multiple times so I need the code to just know what the column is called - it can then retrieve it (updating would be done against the currency column directly).

How can I retrieve the values for such a column when the generated SQL has given the column an alias? Is there a way of finding/calculating the alias? My current code is doing a 'startsWith' as the generated alias 'startsWith' a substring of the column name.

Thanks

Michael

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

I think that in this case, you want to map the same column multiple times. Just use either insert="false" update="false", or formula instead of column, when defining the currency column.

Code:

<class ...>
  ...
  <property name="Income" type="Monetary">
    <column name="IncomeValue"/>
    <formula>Currency</formula>
  </property>
  <property name="Outgoings" type="Monetary">
    <column name="OutgoingsValue"/>
    <formula>Currency</formula>
  </property>
  ...
</class>

mmcgovern · **Posted:** Wed Jul 12, 2006 9:52 pm

Thanks - now I'll complicate things by saying its EJB3, which means I'm using annotations.

Do I have?

@Columns( columns=({@Column(name="amount_column"),@Formula("currency_column")})

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

Don't know about formula in EJB3 annotations, but I know that @column has insertable and updatable attributes. Set them both to false and that should work too.

mmcgovern · **Posted:** Wed Jul 12, 2006 11:26 pm

Thanks - I tried insert="false" update="false" - not quite the right syntax.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

I think in annotations it would be

Code:

insertable=false updatable=false

No quotes.

mmcgovern · **Posted:** Thu Jul 13, 2006 6:08 am

Unfortunately Hibernate won't allow a mix of columns that are insertable/updatable and those that aren't.

Also tried the @Formula but its not allowed inside the @Columns annotation.

Which, I think, brings me back to trying to do a simple mapping to only the amount column and then have the nullSafeGet somehow find the right column alias for the known currency column.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

I don't know how its done with annotations, but you can create UserTypes that take parameters, by having the type extend ParameterizedUserType. Then make the name of the other column a parameter of the type. There are examples in the refdocs section 5.2.3.

mmcgovern · **Posted:** Thu Jul 13, 2006 6:39 pm

Thanks - the problem is that I dont know what the alias is, so the parameter can't really help me.

If I have a join between tables that both have a default currency column with the same name then only the alias can differentiate them.

Unless I can pass something dynamic into a parameter like some meta data that allows me to call the getAliasName on the particular column.