I'm a bit restricted in posting original code but I'll do my best :-)
Ok.
Brian McCallister wrote:
Saw your original message and am thinking about this one.at runtime and that is the main problem. During load time I could solve by using the attributes at the repository.
Any chance you can post specifics?
Does value need to change while running, or is it just dependent upon something at load time?
I have two classes A and B and A has a 1:n relationshop to B.
<class-descriptor class="A" table="A">
<field-descriptor id="1"
name="a_key"
column="a_key"
jdbc-type="INTEGER"
/>
<collection-descriptor name="b_col" element-class-ref="B" auto-retrieve="true" auto-update="false" auto-delete="false" proxy="false" refresh="false">
<inverse-foreignkey field-id-ref="2"/>
<query-customizer
class="QueryCustomizerFilterImpl">
<attribute
attribute-name="attr1"
attribute-value="value1"
/>
</query-customizer>
</collection-descriptor>
</class-descriptor>
<class-descriptor class="B" table="B">
<field-descriptor id="1"
name="b_key"
column="b_key"
jdbc-type="INTEGER"
primarykey="true"
autoincrement="false"
/>
<field-descriptor id="2"
name="a_key"
column="a_key"
jdbc-type="INTEGER"
primarykey="true"
autoincrement="false"
/>
</class-descriptor> Criteria crit = new Criteria();
crit.addEqualTo("key", "value1"); Criteria crit2 = new Criteria();
crit2.addEqualTo("b_col.b_key", "pk_value_of_B"); Criteria crit3 = new Criteria();
crit3.addAndCriteria(crit);
crit3.addAndCriteria(crit2); Query q = QueryFactory.newQuery(A.class, crit3);
Collection results = broker.getCollectionByQuery(q);I would like to get a collection a.b_col which contains only the elements of B which has the primary key "pk_value_of_B" not ALL
values. The query from above gives the correct instance of A but the collection is filled with all existing b which are very much.
So I build a QueryCustomizer where I can add the missing select criteria to the query which was build from OJB to load ALL b.
public Query customizeQuery(Object anObject, PersistenceBroker aBroker, CollectionDescriptor aCod, QueryByCriteria aQuery)
{
aQuery.getCriteria().addEqualTo("b_key","pk_value_of_B");
return aQuery;
}
My problem is how to get the "pk_value_of_B" to the QueryCustomizer instance. The QueryCustomizer instance is constructed by OJB
so the default constructor is called, no way to pass a argument with my pk value. After that OJB calls the customizeQuery method and again
it looks like there is no way to get my key in there.
Hope this is more readable and a bit more detailed.
best regards,
Guido
-Brian
On Fri, 2003-12-19 at 10:09, Guido Beutler wrote:
Hello,
This is a repost with a better subject, hoping to get a hint.
I build a custom QueryCustomizer implementation to restrict the retrieved values of a collection to a known primary key.
I saw that I could add attributes at the deployment descriptor but the value of the
primary key changes dynamically during my application.
My sample:
public Query customizeQuery(Object anObject, PersistenceBroker aBroker, CollectionDescriptor aCod, QueryByCriteria aQuery)
{
aQuery.getCriteria().addEqualTo("field","value");
return aQuery;
}
The "value" should change dynamically. Is there really no way to pass additional dynamic arguments to the implementation?
IA Simple workaround is to use System properties but of course this just a hack for a test case. It's not thread save, it's slow
etc.
I found no way to find out where the current query came from to build sonething like a callback. Extending the Query implementation by
a user object would be a solution buit this modification shouldn't be done without consulting the OJB crew.
Implementing a user object might be difficult because the querry which is passed to the QueryCustomizer is generated by OJB and is
not directly coming from my code. So a modified Query would mean that the user object must be passed around by OJB Broker.
I still think that I miss something.
best regards,
Guido
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