Class QueryResults

java.lang.Object
org.exolab.castor.persist.QueryResults

public final class QueryResults extends Object
The result of a query in the context of a transaction. A query is executed against the cache engine in the context of a transaction. The result of a query is this object that can be used to obtain the next object in the query.
Version:
$Revision: 7951 $ $Date: 2006-04-22 11:05:30 -0600 (Sat, 22 Apr 2006) $
Author:
Assaf Arkin
  • Constructor Details

  • Method Details

    • getTransaction

      public TransactionContext getTransaction()
      Returns the transaction context in which this query was opened. The transaction may be closed.
      Returns:
      The query's transaction context
    • getQuery

      public PersistenceQuery getQuery()
      Returns the associated query.
      Returns:
      The query
    • getResultType

      public Class getResultType()
      Returns the type of object returned by this query.
      Returns:
      The type of object returned by this query
    • nextIdentity

      public Object nextIdentity() throws PersistenceException
      Returns the identity of the next object to be returned. Calling this method multiple time will skip objects. When the result set has been exhuasted, this method will return null.
      Returns:
      The identity of the next object
      Throws:
      PersistenceException - An error reported by the persistence engine
      TransactionNotInProgressException - The transaction has been closed
    • fetch

      public Object fetch() throws PersistenceException
      Loads the specified object with the identity. The identity must have been retrieved with a call to nextIdentity().

      If the object is locked by another transaction this method will block until the lock is released, or a timeout occured. If a timeout occurs or the object has been deleted by the other transaction, this method will report an. The query may proceed to the next identity.

      If the object has been deleted in this transaction, this method will report an. However, the caller may iterate to and obtain the next object.

      This method is equivalent to TransactionContext.fetch(org.exolab.castor.persist.ClassMolder, org.exolab.castor.persist.spi.Identity, org.exolab.castor.mapping.AccessMode) with a know cache engine, identity and lock and acts on the query results rather than issuing a new query to load the object.

      Returns:
      The loaded object
      Throws:
      PersistenceException - An error reported by the persistence engine. The object was not found in persistent storage. The transaction has been closed. Could not acquire a lock on the object.
    • close

      public void close()
      Close the query and release all resources held by the query.
    • absolute

      public boolean absolute(int row) throws PersistenceException
      Throws:
      PersistenceException
    • size

      public int size() throws PersistenceException
      Throws:
      PersistenceException