Re: Collection Query, continuation

Sun, 03 Jul 2005 13:10:40 -0700 

Armin Waibel wrote:
how did you map the sub-classes of Citation.class, do you use 'extent-class' elements in mapping for Citation.class or do you use 'super-references' in the sub-classes? 
here is what I have:
<class-descriptor class="edu.uci.ics.sigmoid.Citation">
  <extent-class class-ref="edu.uci.ics.sigmoid.OJBCitation" />
  <extent-class class-ref="edu.uci.ics.sigmoid.Article" />
  <extent-class class-ref="edu.uci.ics.sigmoid.Book" />
  <extent-class class-ref="edu.uci.ics.sigmoid.Booklet" />
  <extent-class class-ref="edu.uci.ics.sigmoid.Unpublished" />
  <extent-class class-ref="edu.uci.ics.sigmoid.TechReport" />
  <extent-class class-ref="edu.uci.ics.sigmoid.Proceedings" />
  <extent-class class-ref="edu.uci.ics.sigmoid.PhDThesis" />
  <extent-class class-ref="edu.uci.ics.sigmoid.MiscCitation" />
  <extent-class class-ref="edu.uci.ics.sigmoid.MastersThesis" />
  <extent-class class-ref="edu.uci.ics.sigmoid.Manual" />
  <extent-class class-ref="edu.uci.ics.sigmoid.InProceedings" />
  <extent-class class-ref="edu.uci.ics.sigmoid.InCollection" />
  <extent-class class-ref="edu.uci.ics.sigmoid.InBook" />
  <extent-class class-ref="edu.uci.ics.sigmoid.Conference" />
</class-descriptor>

should I change it somehow?

Kirill

Kirill Petrov wrote:


Hello guys,

is it indeed a bug or am I doing something wrong?? Please, help.

thanks,

Kirill


you should try using the path class hint:

Criteria crit = new Criteria();
crit.addLike("reactions.name", rName);
QueryByCriteria query = new QueryByCriteria(Model.class, crit1);
query.addPathClass("reactions", BidirectionalReaction.class);
in this case ojb will only use BidirectionalReaction when processing the relationship "reactions". 

there's a test case called PathTest for this feature.




I guess there is a bug in this feature:

here is the code that I have
public static Collection findModelsByAuthorsName(String aName) {
PersistenceBroker broker = PersistenceBrokerFactory.defaultPersistenceBroker(); 

    try{
      Criteria crit = new Criteria();
      crit.addLike("sources.author", aName);
QueryByCriteria query = new QueryByCriteria(Model.class, crit, true); 
      query.addPathClass("sources", Citation.class);
      return broker.getCollectionByQuery(query);
    } finally {
      broker.close();
    }
  }
when I run it I get an error (below). The problem is that Citation is another superclass that has a number of classes that implement it. If instead of Citation I use OJBCitation (which is not extended by any class) then everything works fine. 

Do you have a fix for this or am I doing something wrong?
[org.apache.ojb.broker.accesslayer.sql.SqlGeneratorDefaultImpl] DEBUG: createTableAlias2: path: sources* tableAlias: model_sources_knowledge_source A1 [org.apache.ojb.broker.accesslayer.sql.SqlGeneratorDefaultImpl] DEBUG: Result of getTableAlias(): null A2 [org.apache.ojb.broker.accesslayer.sql.SqlGeneratorDefaultImpl] DEBUG: SQL:SELECT DISTINCT A0._id,A0.name,A0.extended_description,A0.license_id,A0.unique_dbid,A0.comment FR\ OM model A0 INNER JOIN (model_sources_knowledge_source A1 INNER JOIN null A2 ON A1.knowledge_source_id=A2._id) ON A0._id=A1.model_id WHERE author LIKE ? [org.apache.ojb.broker.accesslayer.JdbcAccessImpl] ERROR: SQLException during the execution of the query (for edu.uci.ics.sigmoid.OJBModel): ERROR: syntax error at or near \ 
"null"
ERROR: syntax error at or near "null"
java.sql.SQLException: ERROR: syntax error at or near "null"
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1471) at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1256) at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:175) at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:389) at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:330) at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:240) 




jakob

Kirill Petrov schrieb:


Hello everybody,
Recently, I asked a question how can a query an object having a property which is a collection of objects. I received an answer, so, now my query looks like this: 

public static Collection findModelsByReactionsName(String rName) {
PersistenceBroker broker = PersistenceBrokerFactory.defaultPersistenceBroker(); 

    try{
      Criteria crit = new Criteria();
      crit.addLike("reactions.name", rName);
      QueryByCriteria query = new QueryByCriteria(Model.class, crit);
      return broker.getCollectionByQuery(query);
    } finally {
      broker.close();
    }
  }
Now, I have another problem. There are several subclasses of Reaction. Those subclasses of course have their own properties. For example, "BidirectionalReaction" has a property "reverseRate". I want to query the models by this property which implies that I am looking only for the models that have BidirectionalReactions in them. But I don't know how to do that. If I just specify "reactions.reverseRate" in the query, OJB generates SQL that would try to query using all the possibe subclasses. The SQL of course fails since only one table would have a column corresponding to reverseRate. 

How do I write such a query?

thanks a lot,

Kirill

PS

Here is explanation of my object model:

I have an object model in which there are two objects: Model and
Reactiont. This is basically n to m relationship. Model can have a number of Reactions. Reactions can be in a number of Models. 
In Java this is implemented by a Collection property in Model class.

I want to construct a query that allows me to find all the models that
have a particular reaction in them.



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