PersistenceQuery (Castor JavaDoc)

All Known Implementing Classes:

AbstractCallQuery, MultiRSCallQuery, PostgreSQLCallQuery, ReturnedRSCallQuery, SQLQuery
```
public interface PersistenceQuery
```
The persistence engine implements this interface in order to allow queries to be performed and multiple objects to be returned. This is an extension of Persistence.load(java.lang.Object, org.castor.persist.ProposedEntity, org.exolab.castor.persist.spi.Identity, org.exolab.castor.mapping.AccessMode) for dealing with complex queries.
The caller takes full responsibility to assure integrity of transactions and object caching and only relies on the engine to assist in assuring that through the mechanisms available to it.
A query may be created once and used multiple times by calling the execute(Object, AccessMode, boolean) method. Query parameters are set each time prior to executing the query.
See Persistence for information about locks, loading objects, identities and stamps.

Version:

$Revision: 8104 $ $Date: 2006-04-11 15:26:07 -0600 (Tue, 11 Apr 2006) $

Author:

Assaf Arkin

See Also:

Persistence

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`absolute(int row)`	Moves the result of the query to the absolute position in the resultset.
`void`	`close()`	Close the query and release all resources held by the query.
`void`	`execute(java.lang.Object conn, AccessMode accessMode, boolean scrollable)`	Execute the query with the give connection and lock type.
`void`	`fetch(ProposedEntity proposedObject)`	Loades the object.
`java.lang.Class<?>`	`getResultType()`	Returns the type of object returned by this query.
`Identity`	`nextIdentity(Identity identity)`	Returns the identity of the next object to be returned.
`void`	`setParameter(int index, java.lang.Object value)`	Sets the value of a paramter.
`int`	`size()`	Finds the size of the resulting resultset from the query.

- Method Detail
  - setParameter
```
void setParameter(int index,
                  java.lang.Object value)
```
    Sets the value of a paramter. Will complain if the parameter is not of the specified type.
    
    Parameters:
    
    index - The parameter index
    
    value - The parameter value
  - getResultType
```
java.lang.Class<?> getResultType()
```
    Returns the type of object returned by this query.
    
    Returns:
    
    The type of object returned by this query
  - execute
```
void execute(java.lang.Object conn,
             AccessMode accessMode,
             boolean scrollable)
      throws PersistenceException
```
    Execute the query with the give connection and lock type. After a successful return the query results will be returned by calling nextIdentity(org.exolab.castor.persist.spi.Identity) and fetch(org.castor.persist.ProposedEntity). The query parameters will be reset. A new query may be issued by providing new query parameters and calling execute(Object, AccessMode, boolean).
    
    Parameters:
    
    conn - An open connection
    
    accessMode - The access mode (null equals shared)
    
    scrollable - The db cursor mode.
    
    Throws:
    
    PersistenceException - An invalid query or an error reported by the persistence engine.
  - nextIdentity
```
Identity nextIdentity(Identity identity)
               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.
    
    Parameters:
    
    identity - The identity of the previous object, null if this method is called for the first time
    
    Returns:
    
    The identity of the next object, null if the result set has been exhausted
    
    Throws:
    
    PersistenceException - An error reported by the persistence engine
  - fetch
```
void fetch(ProposedEntity proposedObject)
    throws PersistenceException
```
    Loades the object. This method must be called immediately after nextIdentity(org.exolab.castor.persist.spi.Identity) with the same identity.
    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 ObjectNotFoundException. The query may proceed to the next identity.
    This method is equivalent to Persistence.load(java.lang.Object, org.castor.persist.ProposedEntity, org.exolab.castor.persist.spi.Identity, org.exolab.castor.mapping.AccessMode) with a known cache engine and access mode and acts on the query results rather than issuing a new query to load the object.
    
    Parameters:
    
    proposedObject - The fields to load into
    
    Throws:
    
    PersistenceException - The object was not found in persistent storage or any other persistence error occured.
    
    See Also:
    
    Persistence.load(java.lang.Object, org.castor.persist.ProposedEntity, org.exolab.castor.persist.spi.Identity, org.exolab.castor.mapping.AccessMode)
  - close
```
void close()
```
    Close the query and release all resources held by the query.
  - absolute
```
boolean absolute(int row)
          throws PersistenceException
```
    Moves the result of the query to the absolute position in the resultset.
    
    Parameters:
    
    row - The row to move to
    
    Throws:
    
    PersistenceException - A persistence error occured
  - size
```
int size()
  throws PersistenceException
```
    Finds the size of the resulting resultset from the query.
    
    Throws:
    
    PersistenceException

Interface PersistenceQuery

Method Summary

Method Detail

setParameter

getResultType

execute

nextIdentity

fetch

close

absolute

size