Hibernate Annotations, specifying which members of a component to make persistent

Question

I have a Price object consisting of two MonetaryValues where one MonetaryValue consists of an amount and a currency.

If I configure the OR-mapping the XML-way, I can do this

    <component name="baseAmount" lazy="false" class="MonetartyValue">
        <property name="amount" column="baseAmount" precision="20" scale="2" not-null="true" />
        <!-- <property name="currency" column="baseCurrency" not-null="true" /> -->
    </component>

    <component name="originalAmount" lazy="false" class="MonetaryValue">
        <property name="amount" column="originalAmount" precision="20" scale="2" not-null="true" />
        <property name="currency" column="originalCurrency" not-null="true" />
    </component>

i.e. choose not to persist the baseCurrency element (since it is implicit and always the same).

Is it possible to achieve this in an annotation-configuration manner?

---

If I just do like this, and leave out the baseCurrency attribute, it will be persisted anyway, with a default name.

@Embedded
@AttributeOverrides ( {
 @AttributeOverride(name="amount", column= @Column(name="baseAmount"))
} )
private MonetaryValue baseAmount;

@Embedded
@AttributeOverrides ( { 
 @AttributeOverride(name="amount", column= @Column(name="originalAmount")),
 @AttributeOverride(name="currency", column= @Column(name="originalCurrency"))
} )
private MonetaryValue originalAmount;

It also not possible to make the property currency of MonetaryValue transient, since then it will never be saved.

So, is it possible to achieve what the above XML-mapping does, by means of annotations?

---

Just as mtpettyp suggests, I want to store two MonetaryValue in a a table, using only three columns. As Autocracy suggests in his comment, you could definitely solve the problem with inheritance. But then again, you can also solve it with with a custom .hbm.xml-mapping file instead of using annotations. I am not certain which is more correct, but I'm still curious if it's possible to solve with neither...

Answer 1

I'm still confused by your question, but I'm going to answer with a guess that you are trying to read baseCurrency without ever updating it?

// Use this in the override statement for your first baseCurrency
@Column(insertable=false,updatable=false)

Resulting in:

@Embedded
@AttributeOverrides ( {
        @AttributeOverride(name="amount", column= @Column(name="baseAmount"))
        @AttributeOverride(name="currency", column= @Column(name="baseCurrency", insertable=false,updatable=false))
} )
private MonetaryValue baseAmount;

@Embedded
@AttributeOverrides ( { 
        @AttributeOverride(name="amount", column= @Column(name="originalAmount")),
        @AttributeOverride(name="currency", column= @Column(name="originalCurrency"))
} )
private MonetaryValue originalAmount;

You should clarify more, though, if that's not what you mean. I really can't tell what you're trying to do here.