org.datanucleus.store.rdbms.query

Class ResultMetaDataROF

java.lang.Object

org.datanucleus.store.rdbms.query.ResultMetaDataROF

All Implemented Interfaces:

ResultObjectFactory

public class ResultMetaDataROF
extends Object
implements ResultObjectFactory

ResultObjectFactory that operates using a QueryResultMetaData and returns objects based on the definition. A QueryResultMetaData allows for a row of a ResultSet to be returned as a mix of :-

• a number of persistent objects (made up of several ResultSet columns)
• a number of Objects (from individual ResultSet columns)

Each call to getObject() will then return a set of objects as per the MetaData definition.

ResultSet to object mapping

Each row of the ResultSet has a set of columns, and these columns are either used for direct outputting back to the user as a "simple" object, or as a field in a persistent object. So you could have a situation like this :-

 ResultSet Column   Output Object
 ================   =============
 COL1               PC1.field1
 COL2               PC1.field2
 COL3               Simple Object
 COL4               PC2.field3
 COL5               PC2.field1
 COL6               PC2.field2
 COL7               Simple Object
 COL8               PC1.field3
 ...
 

So this example will return an Object[4] ... Object[0] = instance of PC1, Object[1] = instance of PC2, Object[2] = simple object, Object[3] = simple object. When creating the instance of PC1 we take the ResultSet columns (COL1, COL2, COL8). When creating the instance of PC2 we take the ResultSet columns (COL5, COL6, COL4).

Constructor Summary

Constructors

Constructor and Description
ResultMetaDataROF(RDBMSStoreManager storeMgr, org.datanucleus.metadata.QueryResultMetaData qrmd) Constructor.

Method Summary

Modifier and Type	Method and Description
Object	getObject(org.datanucleus.ExecutionContext ec, ResultSet rs) Accessor for the object(s) from a row of the ResultSet.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ResultMetaDataROF

public ResultMetaDataROF(RDBMSStoreManager storeMgr,
                         org.datanucleus.metadata.QueryResultMetaData qrmd)

Constructor.

Parameters:

storeMgr - RDBMS StoreManager

qrmd - MetaData defining the results from the query.

Method Detail

getObject

public Object getObject(org.datanucleus.ExecutionContext ec,
                        ResultSet rs)

Accessor for the object(s) from a row of the ResultSet.

Specified by:

getObject in interface ResultObjectFactory

Parameters:

ec - execution context

rs - ResultSet

Returns:

The object(s) for this row of the ResultSet.