uk.ac.ed.epcc.webapp.jdbc.expr

Class GeneralMapMapper<K,R>

java.lang.Object

uk.ac.ed.epcc.webapp.AbstractContexed

uk.ac.ed.epcc.webapp.jdbc.expr.SQLGroupMapper<java.util.Map<K,R>>

uk.ac.ed.epcc.webapp.jdbc.expr.GeneralMapMapper<K,R>

Type Parameters:

K -

R -

All Implemented Interfaces:

Contexed, ResultMapper<java.util.Map<K,R>>

Direct Known Subclasses:

MapMapper

public abstract class GeneralMapMapper<K,R>
extends SQLGroupMapper<java.util.Map<K,R>>
implements Contexed

SQLGroupMapper to populate a Map from a SQL query.

Field Summary

Fields inherited from class uk.ac.ed.epcc.webapp.jdbc.expr.SQLGroupMapper

qualify, use_alias

Fields inherited from class uk.ac.ed.epcc.webapp.AbstractContexed

conn

Constructor Summary

Constructors

Constructor and Description
GeneralMapMapper(AppContext c)

Method Summary

Modifier and Type	Method and Description
protected R	combine(R a, R b) If more than one database value maps to the same key we may have to combine multiple results.
java.util.Map<K,R>	makeDefault() Create a default Object to be returned if no SQL results are generated.
protected abstract K	makeKey(java.sql.ResultSet rs) Make the key object from the ResultSet
java.util.Map<K,R>	makeObject(java.sql.ResultSet rs) Convert a ResultSet into a domain object.
protected abstract R	makeResult(java.sql.ResultSet rs) make the result object from the ResultSet

Methods inherited from class uk.ac.ed.epcc.webapp.jdbc.expr.SQLGroupMapper

addAverage, addClause, addCount, addCount, addKey, addKeyList, addMaxDate, addMaxNumber, addMinDate, addMinNumber, addSQLAverage, addSQLCount, addSum, getModify, getModifyParameters, getRequiredFilter, getTarget, getTargetObject, getTargetParameters, setQualify, setUseAlias

Methods inherited from class uk.ac.ed.epcc.webapp.AbstractContexed

getContext, getLogger, resetLogger

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.ac.ed.epcc.webapp.Contexed

getContext

Constructor Detail

GeneralMapMapper

public GeneralMapMapper(AppContext c)

Method Detail

makeDefault

public java.util.Map<K,R> makeDefault()

Description copied from interface: ResultMapper

Create a default Object to be returned if no SQL results are generated. If there is no obvious default result then return null. Where there is an obvious result (like a sum=0 or an empty Map) this is less error prone than trying to trap null at the calling level. Note that FilterFinder can optionally check for null results and generate exceptions this still fails but makes it easier to find the problem.

Specified by:

makeDefault in interface ResultMapper<java.util.Map<K,R>>

Returns:

domain object

makeObject

public java.util.Map<K,R> makeObject(java.sql.ResultSet rs)
                              throws DataException,
                                     java.sql.SQLException

Description copied from interface: ResultMapper

Convert a ResultSet into a domain object. The ResultSet should already be positioned at the correct starting Row to start creating the object It is legal for this method to return null to indicate the ResultSet represents an invalid record that should be ignored by the higher levels of the code.

Specified by:

makeObject in interface ResultMapper<java.util.Map<K,R>>

Parameters:

rs - ResultSet or null

Returns:

domain object

Throws:

DataException

java.sql.SQLException

combine

protected R combine(R a,
                    R b)
             throws CombineException

If more than one database value maps to the same key we may have to combine multiple results. This method defines how multiple results are combined. If combination is not possible this method needs to throw CombineException if the first parameter is non-null.

Parameters:

a - previous value

b - new value

Returns:

combined value

Throws:

CombineException

makeKey

protected abstract K makeKey(java.sql.ResultSet rs)
                      throws DataException,
                             java.sql.SQLException

Make the key object from the ResultSet

Parameters:

rs -

Returns:

Throws:

DataFault

DataException

java.sql.SQLException

makeResult

protected abstract R makeResult(java.sql.ResultSet rs)
                         throws DataException,
                                java.sql.SQLException

make the result object from the ResultSet

Parameters:

rs -

Returns:

Throws:

DataFault

DataException

java.sql.SQLException