Re: java.lang.NullPointerException for SqlQueryStatement

Mon, 11 Oct 2004 01:53:32 -0700 

Reda Benzair wrote:

Jakob Braeuchi wrote:

hi reda,

the problem is imo that the subqueries are not extent aware (as mentioned in the other post about splitCriteria).

i suggest you separate the queries. the first one retrieves all the ids and the second uses these ids in an IN-clause:

ReportQueryByCriteria subQuery = new ReportQueryByCriteria(Company.class, compCrit);
subQuery.setAttributes(new String[] {"cpyId"});
Iterator subIter = broker.getReportQueryIteratorByQuery(subQuery);
Collection subIds = new ArrayList();
while (subIter.hasNext())
{
Object[] id = (Object[])subIter.next();
subIds.add(id[0]);
}

Query empQuery = new QueryByCriteria(Employee.class, crit);
Criteria empCrit = new Criteria();
empCrit.addLike("name", "%A%");
empCrit.addIn("cpyId", subIds);

hth
jakob

Reda Benzair schrieb:

Hi,

I am facing a problem you already encountered, but don't seem to find a solution.
*SUMMARY*
I would like to include a reportQuery that returns only one attribute inside a Criteria :

*EXISTING*

Using OJB 1.0, on JDK 1.4.2 (with Tomcat 4.1.30)

Tables:

   * A Company has a name
   * An Employee has a name
   * An Employee has a Company

class Company
{
   Integer cpyId; //the ID
   String name;  //the name

   /* Collection of employees*/
   Employee[] employees;
}

class Employee
{
   Integer empId; //the ID
   String name;  //the name

   /*  Reference to a company */
   Integer cpyId;
   Company company;
}

Mapping:
In fact, Company is an interface with one single extent CompanyImpl.
Employee is an interface with one single extent EmployeeImpl.

------------------------------------------------------------------------

*PROBLEM*
I want to get all the user with an 'A' in their name, and who belong to a company with a 'B' in its name.

I know it could be done like this:


Criteria crit = new Criteria();
crit.addLike("company.name", "%B%");
crit.addLike("name", "%A%");
broker.getIteratorByQuery(new QueryByCriteria(Employee.class, crit));

but this is a simple exemple to help you understand my problem. I'm trying to use a subquery (because my subquery is much more complex than a simple like)

   Criteria compCrit = new Criteria();
   compCrit.addLike("name", "%B%");
   Query empQuery = new QueryByCriteria(Employee.class, crit);
       Criteria empCrit = new Criteria();
   empCrit.addLike("name", "%A%");
       ReportQueryByCriteria subQuery = new
   ReportQueryByCriteria(Company.class, compCrit);
   subQuery.setAttributes(new String[] {"cpyId"});
       empCrit.addIn("cpyId", subQuery);
       broker.getIteratorByQuery(empQuery);

This second piece of code generate a NullPointerException :


java.lang.NullPointerException

at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement$TableAlias.hashCode(SqlQueryStatement.java:1920) 


at java.util.HashMap.hash(HashMap.java:261)

at java.util.HashMap.put(HashMap.java:379)

at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.splitCriteria(SqlQueryStatement.java:1630)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.<init>(SqlQueryStatement.java:130)


at org.apache.ojb.broker.accesslayer.sql.SqlSelectStatement.<init>(SqlSelectStatement.java:64)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.getSubQuerySQL(SqlQueryStatement.java:910)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendSubQuery(SqlQueryStatement.java:891)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendParameter(SqlQueryStatement.java:876)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryState ment.appendInCriteria(SqlQueryStatement.java:704)

at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendCriteria(SqlQueryStatement.java:783)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendSQLClause(SqlQueryStatement.java:856)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.asSQLStatement(SqlQueryStatement.java:609)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendClause(SqlQueryStatement.java:532)


at org.apache.ojb.broker.accesslayer.sql.SqlQueryStatement.appendWhereClause(SqlQueryStatement.java:484)


at org.apache.ojb.broker.accesslayer.sql.SqlSelectStatement.getStatement(SqlSelectStatement.java:251)


at org.apache.ojb.broker.accesslayer.sql.SqlGeneratorDefaultImpl.getPreparedSelectStatement(SqlGeneratorDefaultImpl.java:151)


at org.apache.ojb.broker.accesslayer.JdbcAccessImpl.executeQuery(JdbcAccessImpl.java:276)


at org.apache.ojb.broker.accesslayer.RsQueryObject.perfo rmQuery(RsQueryObject.java:74)

at org.apache.ojb.broker.accesslayer.RsIterator.<init>(RsIterator.java:183)


at org.apache.ojb.broker.core.RsIteratorFactoryImpl.createRsIterator(RsIteratorFactoryImpl.java:58)


at org.apache.ojb.broker.core.PersistenceBrokerImpl.getRsIteratorFromQuery(PersistenceBrokerImpl.java:1831)


at org.apache.ojb.broker.core.PersistenceBrokerImpl.getIteratorFromQuery(PersistenceBrokerImpl.java:1331)


at org.apache.ojb.broker.core.QueryReferenceBroker.getCollectionByQuery(QueryReferenceBroker.java:111)


at org.apache.ojb.broker.core.QueryReferenceBroker.getCollectionByQuery(QueryReferenceBroker.java:233)


at org.apache.ojb.broker.core.QueryReferenceBroker.getCollectionByQuery(QueryReferenceBroker.java:253)


at org.apache.ojb.broker.core.PersistenceBrokerImpl.getCollectionByQuery(PersistenceBrokerImpl.java:1215)


at org.apache.ojb.broker.core.DelegatingPersistenceBroker.getCollectionByQuery(DelegatingPersi stenceBroker.java:338)

at org.apache.ojb.broker.core.DelegatingPersistenceBroker.getCollectionByQuery(DelegatingPersistenceBroker.java:338)


In fact, in this case, I would simply like OJB to retreive all the Employee that are returned by

select * from employee where name like '%A%' and cpyId in (select cpyId from company where name like '%B%')


I've found out you faced exactly the same problem, in a thread entitled "SqlQueryStatement.splitCriteria -> NullPointerException". Did you reach a solution?


thinks all

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Thank you Jakob,
I had already used the workaround you propose, but I'd rather use one single, "clean" query.
Will subqueries be extent-aware in future releases?
Thank you again,



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