er.extensions.eof
Class ERXDatabaseContextDelegate

java.lang.Object
  er.extensions.eof.ERXDatabaseContextDelegate

public class ERXDatabaseContextDelegate
extends java.lang.Object

This delegate implements several methods from the formal interface EODatabaseContext.Delegate. Of special note this class adds the ability for enterprise objects to generate their own primary keys, correctly throws an exception when a toOne relationship object is not found in the database and adds debugging abilities to tracking down when faults are fired. It also supports a cache for array fault that is checked before they are fetched from the database.

Nested Class Summary

static interface	ERXDatabaseContextDelegate.AutoBatchFaultingEnterpriseObject Interface to provide auto-magic batch fetching.
static interface	ERXDatabaseContextDelegate.BatchHandler
static class	ERXDatabaseContextDelegate.ObjectNotAvailableException

Field Summary

static int	autoBatchFetchSize Holds the auto batch fetch size.
static org.apache.log4j.Logger	batchLog Faulting logging support, logging category: er.transaction.adaptor.Batching
static java.lang.String	DatabaseContextFailedToFetchObject
static org.apache.log4j.Logger	dbLog Faulting logging support, logging category: er.transaction.adaptor.FaultFiring
static org.apache.log4j.Logger	exLog Faulting logging support, logging category: er.transaction.adaptor.Exceptions
static org.apache.log4j.Logger	log Basic logging support
static java.lang.String	THREAD_KEY Batching thread key

Constructor Summary

ERXDatabaseContextDelegate()

Method Summary

ERXArrayFaultCache	arrayFaultCache()
static int	autoBatchFetchSize() Returns the batch size for automatic batch faulting from the System property er.extensions.ERXDatabaseContextDelegate.autoBatchFetchSize.
void	databaseContextDidFetchObjects(com.webobjects.eoaccess.EODatabaseContext dbc, com.webobjects.foundation.NSArray eos, com.webobjects.eocontrol.EOFetchSpecification fs, com.webobjects.eocontrol.EOEditingContext ec) Sets the cache entry for the fetched objects and refreshes the timestamps for fetched objects if batch faulting is enabled.
void	databaseContextDidSelectObjects(com.webobjects.eoaccess.EODatabaseContext dc, com.webobjects.eocontrol.EOFetchSpecification fs, com.webobjects.eoaccess.EODatabaseChannel channel) This delegate method is called every time a fault is fired that needs to go to the database.
boolean	databaseContextFailedToFetchObject(com.webobjects.eoaccess.EODatabaseContext context, java.lang.Object object, com.webobjects.eocontrol.EOGlobalID gid) This is Kelly Hawks' fix for the missing to one relationship.
com.webobjects.foundation.NSDictionary	databaseContextNewPrimaryKey(com.webobjects.eoaccess.EODatabaseContext databaseContext, java.lang.Object object, com.webobjects.eoaccess.EOEntity entity) Provides the ability for new enterprise objects that implement the interface ERXGeneratesPrimaryKeyInterface to provide their own primary key dictionary.
boolean	databaseContextShouldFetchArrayFault(com.webobjects.eoaccess.EODatabaseContext dbc, java.lang.Object obj) This delegate method first checks the arrayFaultCache if it is set before trying to resolve the fault from the DB.
boolean	databaseContextShouldFetchObjectFault(com.webobjects.eoaccess.EODatabaseContext dbc, java.lang.Object obj) Batch fetches to one relationships if enabled.
com.webobjects.foundation.NSArray	databaseContextShouldFetchObjects(com.webobjects.eoaccess.EODatabaseContext dbc, com.webobjects.eocontrol.EOFetchSpecification fs, com.webobjects.eocontrol.EOEditingContext ec) Returns an array of already fetched objects or null if they were not already fetched.
boolean	databaseContextShouldHandleDatabaseException(com.webobjects.eoaccess.EODatabaseContext dbc, java.lang.Exception e) Allows custom handling of dropped connection exceptions.
boolean	databaseContextShouldHandleDatabaseException(com.webobjects.eoaccess.EODatabaseContext databaseContext, java.lang.Throwable throwable) Provides for a hook to get at the original exceptions from the JDBC driver, as opposed to the cooked EOGeneralAdaptorException you get from EOF.
com.webobjects.foundation.NSArray	databaseContextWillPerformAdaptorOperations(com.webobjects.eoaccess.EODatabaseContext dbCtxt, com.webobjects.foundation.NSArray adaptorOps, com.webobjects.eoaccess.EOAdaptorChannel adChannel) Overridden to remove inserts and deletes of the "same" row.
static ERXDatabaseContextDelegate	defaultDelegate() Returns the singleton of the database context delegate
ERXFetchResultCache	fetchResultCache()
void	setArrayFaultCache(ERXArrayFaultCache value)
void	setBatchHandler(ERXDatabaseContextDelegate.BatchHandler handler) Sets the batch handler.
static void	setCurrentBatchObjects(com.webobjects.foundation.NSArray arr)
static void	setDefaultDelegate(ERXDatabaseContextDelegate delegate)
void	setFetchResultCache(ERXFetchResultCache value)

Methods inherited from class java.lang.Object

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

Field Detail

DatabaseContextFailedToFetchObject

public static final java.lang.String DatabaseContextFailedToFetchObject

See Also:

Constant Field Values

log

public static final org.apache.log4j.Logger log

Basic logging support

dbLog

public static final org.apache.log4j.Logger dbLog

Faulting logging support, logging category: er.transaction.adaptor.FaultFiring

exLog

public static final org.apache.log4j.Logger exLog

Faulting logging support, logging category: er.transaction.adaptor.Exceptions

batchLog

public static final org.apache.log4j.Logger batchLog

Faulting logging support, logging category: er.transaction.adaptor.Batching

autoBatchFetchSize

public static int autoBatchFetchSize

Holds the auto batch fetch size.

THREAD_KEY

public static final java.lang.String THREAD_KEY

Batching thread key

See Also:

Constant Field Values

Constructor Detail

ERXDatabaseContextDelegate

public ERXDatabaseContextDelegate()

Method Detail

defaultDelegate

public static ERXDatabaseContextDelegate defaultDelegate()

Returns the singleton of the database context delegate

setDefaultDelegate

public static void setDefaultDelegate(ERXDatabaseContextDelegate delegate)

Parameters:

delegate - - the singleton database context delegate to set

arrayFaultCache

public ERXArrayFaultCache arrayFaultCache()

setArrayFaultCache

public void setArrayFaultCache(ERXArrayFaultCache value)

fetchResultCache

public ERXFetchResultCache fetchResultCache()

setFetchResultCache

public void setFetchResultCache(ERXFetchResultCache value)

databaseContextShouldFetchObjects

public com.webobjects.foundation.NSArray databaseContextShouldFetchObjects(com.webobjects.eoaccess.EODatabaseContext dbc,
                                                                           com.webobjects.eocontrol.EOFetchSpecification fs,
                                                                           com.webobjects.eocontrol.EOEditingContext ec)

Returns an array of already fetched objects or null if they were not already fetched.

Parameters:

dbc -

fs -

ec -

databaseContextDidFetchObjects

public void databaseContextDidFetchObjects(com.webobjects.eoaccess.EODatabaseContext dbc,
                                           com.webobjects.foundation.NSArray eos,
                                           com.webobjects.eocontrol.EOFetchSpecification fs,
                                           com.webobjects.eocontrol.EOEditingContext ec)

Sets the cache entry for the fetched objects and refreshes the timestamps for fetched objects if batch faulting is enabled.

Parameters:

dbc -

eos -

fs -

ec -

databaseContextShouldHandleDatabaseException

public boolean databaseContextShouldHandleDatabaseException(com.webobjects.eoaccess.EODatabaseContext databaseContext,
                                                            java.lang.Throwable throwable)

Provides for a hook to get at the original exceptions from the JDBC driver, as opposed to the cooked EOGeneralAdaptorException you get from EOF. To see the exceptions trace, set the logger er.transaction.adaptor.Exceptions to DEBUG.

Parameters:

databaseContext -

throwable -

databaseContextNewPrimaryKey

public com.webobjects.foundation.NSDictionary databaseContextNewPrimaryKey(com.webobjects.eoaccess.EODatabaseContext databaseContext,
                                                                           java.lang.Object object,
                                                                           com.webobjects.eoaccess.EOEntity entity)

Provides the ability for new enterprise objects that implement the interface ERXGeneratesPrimaryKeyInterface to provide their own primary key dictionary. If the enterprise object implements the above interface then the method primaryKeyDictionary(true) will be called on the object. If the object returns null then a primary key will be generated for the object in the usual fashion.

Parameters:

databaseContext - databasecontext

object - the new enterprise object

entity - the entity of the object

Returns:

primary key dictionary to be used or null if a primary key should be generated for the object.

databaseContextShouldHandleDatabaseException

public boolean databaseContextShouldHandleDatabaseException(com.webobjects.eoaccess.EODatabaseContext dbc,
                                                            java.lang.Exception e)
                                                     throws java.lang.Throwable

Allows custom handling of dropped connection exceptions. This was needed in WebObjects 4.5 because the OracleEOAdaptor wouldn't correctly handle all exceptions of dropped connections. This may not be needed now.

Parameters:

dbc - current database context

e - throw exception

Returns:

if the exception is one of the bad ones that isn't handled then the method handleDroppedConnection is called directly on the database object of the context and false is returned otherwise true.

Throws:

java.lang.Throwable

databaseContextFailedToFetchObject

public boolean databaseContextFailedToFetchObject(com.webobjects.eoaccess.EODatabaseContext context,
                                                  java.lang.Object object,
                                                  com.webobjects.eocontrol.EOGlobalID gid)

This is Kelly Hawks' fix for the missing to one relationship. Delegate on EODatabaseContext that gets called when a to-one fault cannot find its data in the database. The object that is returned is a cleared fault. We raise here to restore the functionality that existed prior to WebObjects 4.5. Whenever a fault fails for a globalID (i.e. the object is NOT found in the database), we raise an EOObjectNotAvailableException.
If you have entities you don't really care about, you can set the system property er.extensions.ERXDatabaseContextDelegate.tolerantEntityPattern to a regular expression that will be tested against the GID entity name. If it matches, then only an error will be logged but no exception will be thrown.

Parameters:

context - database context

object - object that is firing the fault for a given to-one relationship

gid - global id that wasn't found in the database.

databaseContextDidSelectObjects

public void databaseContextDidSelectObjects(com.webobjects.eoaccess.EODatabaseContext dc,
                                            com.webobjects.eocontrol.EOFetchSpecification fs,
                                            com.webobjects.eoaccess.EODatabaseChannel channel)

This delegate method is called every time a fault is fired that needs to go to the database. All we have added is logging statement of the debug priority. This way during runtime a developer can toggle the logger priority settting on and off to see what faults are firing. Also note that when using ERXPatternLayout one can set the option to see full backtraces to the calling method. With this option specified a developer can see exactly which methods are firing faults.

Parameters:

dc - the databasecontext

fs - the fetchspecification

channel - the databasechannel

databaseContextShouldFetchArrayFault

public boolean databaseContextShouldFetchArrayFault(com.webobjects.eoaccess.EODatabaseContext dbc,
                                                    java.lang.Object obj)

This delegate method first checks the arrayFaultCache if it is set before trying to resolve the fault from the DB. It can be a severe performance optimization depending on your setup. Also, it support batch fetching of to-many relationships of EOs that were fetched at the "same" time.

Parameters:

dbc -

obj -

databaseContextShouldFetchObjectFault

public boolean databaseContextShouldFetchObjectFault(com.webobjects.eoaccess.EODatabaseContext dbc,
                                                     java.lang.Object obj)

Batch fetches to one relationships if enabled.

Parameters:

dbc -

obj -

Returns:

true if the fault should get fetched

databaseContextWillPerformAdaptorOperations

public com.webobjects.foundation.NSArray databaseContextWillPerformAdaptorOperations(com.webobjects.eoaccess.EODatabaseContext dbCtxt,
                                                                                     com.webobjects.foundation.NSArray adaptorOps,
                                                                                     com.webobjects.eoaccess.EOAdaptorChannel adChannel)

Overridden to remove inserts and deletes of the "same" row. When you delete from a join table and then re-add the same object, then the order of operations would be insert, then delete and you will get an error because the delete would try to also delete the newly inserted row. Here we just check every insert and see if the deleted contains the same object. If they do, we just skip both operations,

Parameters:

dbCtxt -

adaptorOps -

adChannel -

Author:

chello team!

autoBatchFetchSize

public static int autoBatchFetchSize()

Returns the batch size for automatic batch faulting from the System property er.extensions.ERXDatabaseContextDelegate.autoBatchFetchSize. Default is 0, meaning it's disabled.

Returns:

batch size

setBatchHandler

public void setBatchHandler(ERXDatabaseContextDelegate.BatchHandler handler)

Sets the batch handler.

Parameters:

handler -

setCurrentBatchObjects

public static void setCurrentBatchObjects(com.webobjects.foundation.NSArray arr)