er.extensions.batching
Class ERXBatchingDisplayGroup<T>

java.lang.Object
  com.webobjects.appserver.WODisplayGroup
      er.extensions.appserver.ERXDisplayGroup<T>
          er.extensions.batching.ERXBatchingDisplayGroup<T>

All Implemented Interfaces:

com.webobjects.eocontrol.EOKeyValueArchiving, com.webobjects.eocontrol.EOKeyValueArchiving.Awaking, com.webobjects.foundation.NSDisposable, com.webobjects.foundation.NSKeyValueCoding, com.webobjects.foundation.NSKeyValueCoding.ErrorHandling, java.io.Serializable

public class ERXBatchingDisplayGroup<T>
extends ERXDisplayGroup<T>

Extends WODisplayGroup in order to provide real batching. This is done by adding database specific code to the select statement from the EOFetchSpecification from the WODisplayGroup's EODataSource which must be an EODatabaseDataSource. If used with other datasources, it reverts to the default behaviour.

See Also:

Serialized Form

Author:

dt first version, ak gross hacks, made functional and usable.

Nested Class Summary

static class

ERXBatchingDisplayGroup.FakeArray Dummy array class that is used to provide a certain number of entries.

Nested classes/interfaces inherited from class com.webobjects.appserver.WODisplayGroup

com.webobjects.appserver.WODisplayGroup.Delegate

Nested classes/interfaces inherited from interface com.webobjects.foundation.NSKeyValueCoding

com.webobjects.foundation.NSKeyValueCoding._BooleanFieldBinding, com.webobjects.foundation.NSKeyValueCoding._BooleanMethodBinding, com.webobjects.foundation.NSKeyValueCoding._FieldBinding, com.webobjects.foundation.NSKeyValueCoding._ForwardingBinding, com.webobjects.foundation.NSKeyValueCoding._KeyBinding, com.webobjects.foundation.NSKeyValueCoding._KeyBindingCreation, com.webobjects.foundation.NSKeyValueCoding._MethodBinding, com.webobjects.foundation.NSKeyValueCoding._NumberFieldBinding, com.webobjects.foundation.NSKeyValueCoding._NumberMethodBinding, com.webobjects.foundation.NSKeyValueCoding._ReflectionKeyBindingCreation, com.webobjects.foundation.NSKeyValueCoding.DefaultImplementation, com.webobjects.foundation.NSKeyValueCoding.ErrorHandling, com.webobjects.foundation.NSKeyValueCoding.Null, com.webobjects.foundation.NSKeyValueCoding.UnknownKeyException, com.webobjects.foundation.NSKeyValueCoding.Utility, com.webobjects.foundation.NSKeyValueCoding.ValueAccessor

Nested classes/interfaces inherited from interface com.webobjects.eocontrol.EOKeyValueArchiving

com.webobjects.eocontrol.EOKeyValueArchiving._NullValueSupport, com.webobjects.eocontrol.EOKeyValueArchiving._NumberSupport, com.webobjects.eocontrol.EOKeyValueArchiving._TimestampSupport, com.webobjects.eocontrol.EOKeyValueArchiving.Awaking, com.webobjects.eocontrol.EOKeyValueArchiving.FinishInitialization, com.webobjects.eocontrol.EOKeyValueArchiving.Support

Field Summary

protected int	_batchCount total number of batches
protected com.webobjects.foundation.NSArray<T>	_displayedObjects cache for the displayed objects
protected java.lang.Boolean	_isBatching cache batching flag
protected com.webobjects.foundation.NSArray<java.lang.String>	_prefetchingRelationshipKeyPaths
protected int	_rowCount
protected boolean	_shouldRememberRowCount

Fields inherited from class com.webobjects.appserver.WODisplayGroup

DisplayGroupWillFetchNotification

Fields inherited from interface com.webobjects.foundation.NSKeyValueCoding

_CLASS, NullValue

Fields inherited from interface com.webobjects.foundation.NSKeyValueCoding.ErrorHandling

_CLASS

Fields inherited from interface com.webobjects.foundation.NSDisposable

_CLASS

Fields inherited from interface com.webobjects.eocontrol.EOKeyValueArchiving

_CLASS

Fields inherited from interface com.webobjects.eocontrol.EOKeyValueArchiving.Awaking

_CLASS

Constructor Summary

ERXBatchingDisplayGroup()
Creates a new ERXBatchingDisplayGroup.

Method Summary

int	batchCount() Overridden to return the pre-calculated number of batches
static java.lang.Object	decodeWithKeyValueUnarchiver(com.webobjects.eocontrol.EOKeyValueUnarchiver unarchiver) Decodes an ERXBatchingDisplayGroup from the given unarchiver.
com.webobjects.foundation.NSArray<T>	displayedObjects() Overridden method in order to fetch -only- the rows that are needed.
java.lang.Object	fetch() Overridden to fetch only within displayed limits.
protected com.webobjects.eocontrol.EOFetchSpecification	fetchSpecification() Utility to get the fetch spec from the datasource and the filter qualifier.
com.webobjects.foundation.NSArray<T>	filteredObjects() Overridden to return allObjects() when batching, as we can't qualify in memory.
boolean	hasMultipleBatches() Overridden to refetchIfNecessary() first to ensure we get a correct result in cases where this is called before displayedObjects().
protected boolean	isBatching() Determines if batching is possible.
boolean	isRawRowsForCustomQueries() Returns whether or not fetch specification with custom queries should use raw rows.
protected com.webobjects.foundation.NSArray<T>	objectsInRange(int start, int end) Utility to fetch the object in a given range.
com.webobjects.foundation.NSArray<java.lang.String>	prefetchingRelationshipKeyPaths() Returns the prefetching key paths overriding those in the underlying fetch spec.
protected void	refetch() Utility that does the actual fetching, if a qualifier() is set, it adds it to the dataSource() fetch qualifier.
protected void	refetchIfNecessary() If we're batching and the displayed objects have not been fetched, do a refetch() of them.
int	rowCount() Utility to get at the number of rows when batching.
java.lang.Object	selectFilteredObjects() Selects the visible objects, overridden to fetch all objects.
void	setCurrentBatchIndex(int index) Overriden to clear out our array of fetched objects.
void	setDataSource(com.webobjects.eocontrol.EODataSource eodatasource) Overridden to set the isBatching flag to true if we have an EODatabaseDataSource.
void	setNumberOfObjectsPerBatch(int count) Overriden to clear out our array of fetched objects.
void	setObjectArray(com.webobjects.foundation.NSArray objects) Overridden to update the batch count.
void	setPrefetchingRelationshipKeyPaths(com.webobjects.foundation.NSArray<java.lang.String> prefetchingRelationshipKeyPaths) Sets the prefetching key paths to override those in the underlying fetch spec.
void	setQualifier(com.webobjects.eocontrol.EOQualifier aEoqualifier) Overridden to trigger a refetch.
void	setRawRowsForCustomQueries(boolean rawRowsForCustomQueries) Sets whether or not fetch specification with custom queries should use raw rows.
void	setRowCount(int rowCount) Override the number of rows of results (if you can provide a better estimate than the default behavior).
void	setShouldRememberRowCount(boolean shouldRememberRowCount) Set to true to retain the rowCount() after it is determined once for a particular qualifier.
void	setSortOrderings(com.webobjects.foundation.NSArray nsarray) Overridden to preserve the selected objects.
boolean	shouldRememberRowCount()
protected void	updateBatchCount()
void	updateDisplayedObjects()

Methods inherited from class er.extensions.appserver.ERXDisplayGroup

allObjects, allQualifierOperators, clearExtraQualifiers, displayNextBatch, displayPreviousBatch, indexOfFirstDisplayedObject, indexOfLastDisplayedObject, qualifierFromQueryValues, selectedObject, selectedObjects, setQualifierForKey, setSelectedObjects, setSelectionIndexes, sortedObjects, sortOrderings

Methods inherited from class com.webobjects.appserver.WODisplayGroup

_beginObserverNotification, _deleteObject, _insertObjectAtIndex, _lastObserverNotified, awakeFromKeyValueUnarchiver, clearSelection, currentBatchIndex, dataSource, defaultStringMatchFormat, defaultStringMatchOperator, delegate, delete, deleteObjectAtIndex, deleteSelection, detailKey, displayBatchContainingSelectedObject, dispose, editingContextPresentErrorMessage, encodeWithCoder, encodeWithKeyValueArchiver, endEditing, fetchesOnLoad, finishInitialization, globalDefaultForValidatesChangesImmediately, globalDefaultStringMatchFormat, globalDefaultStringMatchOperator, handleQueryWithUnboundKey, handleTakeValueForUnboundKey, hasDetailDataSource, initWithCoder, inQueryMode, insert, insertedObjectDefaultValues, insertNewObjectAtIndex, insertObjectAtIndex, localKeys, masterObject, numberOfObjectsPerBatch, objectsChangedInEditingContext, objectsInvalidatedInEditingContext, qualifier, qualifyDataSource, qualifyDisplayGroup, queryBindings, queryMatch, queryMax, queryMin, queryOperator, redisplay, relationalQualifierOperators, selectionIndexes, selectNext, selectObject, selectObjectsIdenticalTo, selectObjectsIdenticalToSelectFirstOnNoMatch, selectPrevious, selectsFirstObjectAfterFetch, setDefaultStringMatchFormat, setDefaultStringMatchOperator, setDelegate, setDetailKey, setFetchesOnLoad, setGlobalDefaultForValidatesChangesImmediately, setGlobalDefaultStringMatchFormat, setGlobalDefaultStringMatchOperator, setInQueryMode, setInsertedObjectDefaultValues, setLocalKeys, setMasterObject, setSelectedObject, setSelectsFirstObjectAfterFetch, setValidatesChangesImmediately, stringQualifierOperators, takeValueForKey, toString, unableToSetNullForKey, undoManager, validatesChangesImmediately, valueForKey, willChange

Methods inherited from class java.lang.Object

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

Field Detail

_batchCount

protected int _batchCount

total number of batches

_displayedObjects

protected com.webobjects.foundation.NSArray<T> _displayedObjects

cache for the displayed objects

_isBatching

protected java.lang.Boolean _isBatching

cache batching flag

_prefetchingRelationshipKeyPaths

protected com.webobjects.foundation.NSArray<java.lang.String> _prefetchingRelationshipKeyPaths

_rowCount

protected int _rowCount

_shouldRememberRowCount

protected boolean _shouldRememberRowCount

Constructor Detail

ERXBatchingDisplayGroup

public ERXBatchingDisplayGroup()

Creates a new ERXBatchingDisplayGroup.

Method Detail

setRawRowsForCustomQueries

public void setRawRowsForCustomQueries(boolean rawRowsForCustomQueries)

Sets whether or not fetch specification with custom queries should use raw rows. Defaults to true for backwards compatibility.

Parameters:

rawRowsForCustomQueries - whether or not fetch specification with custom queries should use raw rows

isRawRowsForCustomQueries

public boolean isRawRowsForCustomQueries()

Returns whether or not fetch specification with custom queries should use raw rows.

Returns:

whether or not fetch specification with custom queries should use raw rows

decodeWithKeyValueUnarchiver

public static java.lang.Object decodeWithKeyValueUnarchiver(com.webobjects.eocontrol.EOKeyValueUnarchiver unarchiver)

Decodes an ERXBatchingDisplayGroup from the given unarchiver.

Parameters:

unarchiver - the unarchiver to construct this display group with

Returns:

the corresponding batching display group

refetchIfNecessary

protected void refetchIfNecessary()

If we're batching and the displayed objects have not been fetched, do a refetch() of them.

isBatching

protected boolean isBatching()

Determines if batching is possible.

Returns:

true if dataSource is an instance of EODatabaseDataSource

setDataSource

public void setDataSource(com.webobjects.eocontrol.EODataSource eodatasource)

Overridden to set the isBatching flag to true if we have an EODatabaseDataSource.

Overrides:

setDataSource in class ERXDisplayGroup<T>

batchCount

public int batchCount()

Overridden to return the pre-calculated number of batches

Overrides:

batchCount in class com.webobjects.appserver.WODisplayGroup

setCurrentBatchIndex

public void setCurrentBatchIndex(int index)

Overriden to clear out our array of fetched objects.

Overrides:

setCurrentBatchIndex in class com.webobjects.appserver.WODisplayGroup

setNumberOfObjectsPerBatch

public void setNumberOfObjectsPerBatch(int count)

Overriden to clear out our array of fetched objects.

Overrides:

setNumberOfObjectsPerBatch in class ERXDisplayGroup<T>

displayedObjects

public com.webobjects.foundation.NSArray<T> displayedObjects()

Overridden method in order to fetch -only- the rows that are needed. This is different to the editors methods because a WODisplayGroup would always fetch from the start until the end of the objects from the fetch limit.

Overrides:

displayedObjects in class ERXDisplayGroup<T>

Returns:

the objects that should be diplayed.

hasMultipleBatches

public boolean hasMultipleBatches()

Overridden to refetchIfNecessary() first to ensure we get a correct result in cases where this is called before displayedObjects(). See http://issues.objectstyle.org/jira/browse/WONDER-381

Overrides:

hasMultipleBatches in class com.webobjects.appserver.WODisplayGroup

filteredObjects

public com.webobjects.foundation.NSArray<T> filteredObjects()

Overridden to return allObjects() when batching, as we can't qualify in memory.

Overrides:

filteredObjects in class ERXDisplayGroup<T>

setQualifier

public void setQualifier(com.webobjects.eocontrol.EOQualifier aEoqualifier)

Overridden to trigger a refetch.

Overrides:

setQualifier in class com.webobjects.appserver.WODisplayGroup

setSortOrderings

public void setSortOrderings(com.webobjects.foundation.NSArray nsarray)

Overridden to preserve the selected objects.

Overrides:

setSortOrderings in class ERXDisplayGroup<T>

setPrefetchingRelationshipKeyPaths

public void setPrefetchingRelationshipKeyPaths(com.webobjects.foundation.NSArray<java.lang.String> prefetchingRelationshipKeyPaths)

Sets the prefetching key paths to override those in the underlying fetch spec.

Parameters:

prefetchingRelationshipKeyPaths - the prefetching key paths to override those in the underlying fetch spec

prefetchingRelationshipKeyPaths

public com.webobjects.foundation.NSArray<java.lang.String> prefetchingRelationshipKeyPaths()

Returns the prefetching key paths overriding those in the underlying fetch spec.

Returns:

the prefetching key paths overriding those in the underlying fetch spec

fetchSpecification

protected com.webobjects.eocontrol.EOFetchSpecification fetchSpecification()

Utility to get the fetch spec from the datasource and the filter qualifier.

rowCount

public int rowCount()

Utility to get at the number of rows when batching.

setRowCount

public void setRowCount(int rowCount)

Override the number of rows of results (if you can provide a better estimate than the default behavior). If you guess too low, you will never get more than what you set, but if you guess too high, it will adjust. Call with -1 to have the rows counted again.

Parameters:

rowCount - the number of rows of results

shouldRememberRowCount

public boolean shouldRememberRowCount()

Returns:

true if the rowCount() should be remembered after being determined or false if rowCount() should be re-calculated when the batch changes

setShouldRememberRowCount

public void setShouldRememberRowCount(boolean shouldRememberRowCount)

Set to true to retain the rowCount() after it is determined once for a particular qualifier. Set to false to have rowCount() re-calculated when the batch changes. The default is true.

Parameters:

shouldRememberRowCount - the shouldRememberRowCount to set

objectsInRange

protected com.webobjects.foundation.NSArray<T> objectsInRange(int start,
                                                              int end)

Utility to fetch the object in a given range.

Parameters:

start -

end -

refetch

protected void refetch()

Utility that does the actual fetching, if a qualifier() is set, it adds it to the dataSource() fetch qualifier.

updateBatchCount

protected void updateBatchCount()

setObjectArray

public void setObjectArray(com.webobjects.foundation.NSArray objects)

Overridden to update the batch count.

Overrides:

setObjectArray in class com.webobjects.appserver.WODisplayGroup

fetch

public java.lang.Object fetch()

Overridden to fetch only within displayed limits.

Overrides:

fetch in class ERXDisplayGroup<T>

updateDisplayedObjects

public void updateDisplayedObjects()

Overrides:

updateDisplayedObjects in class com.webobjects.appserver.WODisplayGroup

selectFilteredObjects

public java.lang.Object selectFilteredObjects()

Selects the visible objects, overridden to fetch all objects. Note that this makes sense only when there are only a "few" objects in the list.

Overrides:

selectFilteredObjects in class ERXDisplayGroup<T>