er.extensions.batching

Class ERXBatchingDisplayGroup<T>

java.lang.Object

com.webobjects.appserver.WODisplayGroup

er.extensions.appserver.ERXDisplayGroup<T>

er.extensions.batching.ERXBatchingDisplayGroup<T>

Type Parameters:

T - data type of the displaygroup's objects

All Implemented Interfaces:

EOKeyValueArchiving, EOKeyValueArchiving.Awaking, NSDisposable, NSKeyValueCoding, NSKeyValueCoding.ErrorHandling, 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

Nested Classes

Modifier and Type	Class and Description
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

WODisplayGroup.Delegate

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

NSKeyValueCoding._BooleanFieldBinding, NSKeyValueCoding._BooleanMethodBinding, NSKeyValueCoding._FieldBinding, NSKeyValueCoding._ForwardingBinding, NSKeyValueCoding._KeyBinding, NSKeyValueCoding._KeyBindingCreation, NSKeyValueCoding._MethodBinding, NSKeyValueCoding._NumberFieldBinding, NSKeyValueCoding._NumberMethodBinding, NSKeyValueCoding._ReflectionKeyBindingCreation, NSKeyValueCoding.DefaultImplementation, NSKeyValueCoding.ErrorHandling, NSKeyValueCoding.MapImplementation, NSKeyValueCoding.Null<T>, NSKeyValueCoding.UnknownKeyException, NSKeyValueCoding.Utility, NSKeyValueCoding.ValueAccessor

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

EOKeyValueArchiving._NullValueSupport, EOKeyValueArchiving._NumberSupport, EOKeyValueArchiving._TimestampSupport, EOKeyValueArchiving.Awaking, EOKeyValueArchiving.FinishInitialization, EOKeyValueArchiving.Support

Field Summary

Fields

Modifier and Type	Field and Description
protected int	_batchCount total number of batches
protected NSArray<T>	_displayedObjects cache for the displayed objects
protected Boolean	_isBatching cache batching flag
protected NSArray<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

Constructors

Constructor and Description
ERXBatchingDisplayGroup() Creates a new ERXBatchingDisplayGroup.

Method Summary

Modifier and Type	Method and Description
int	batchCount() Overridden to return the pre-calculated number of batches.
static Object	decodeWithKeyValueUnarchiver(EOKeyValueUnarchiver unarchiver) Decodes an ERXBatchingDisplayGroup from the given unarchiver.
NSArray<T>	displayedObjects() Overridden method in order to fetch -only- the rows that are needed.
Object	fetch() Overridden to fetch only within displayed limits.
protected EOFetchSpecification	fetchSpecification() Utility to get the fetch specification from the datasource and the filter qualifier.
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 NSArray<T>	objectsInRange(int start, int end) Utility to fetch the object in a given range.
NSArray<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.
Object	selectFilteredObjects() Selects the visible objects, overridden to fetch all objects.
void	setCurrentBatchIndex(int index) Overridden to clear out our array of fetched objects.
void	setDataSource(EODataSource datasource) Overridden to set the isBatching flag to true if we have an EODatabaseDataSource.
void	setNumberOfObjectsPerBatch(int count) Overridden to clear out our array of fetched objects.
void	setObjectArray(NSArray objects) Overridden to update the batch count.
void	setPrefetchingRelationshipKeyPaths(ERXKey<?>... prefetchingRelationshipKeyPaths) Sets the prefetching key paths to override those in the underlying fetch spec.
void	setPrefetchingRelationshipKeyPaths(NSArray<String> prefetchingRelationshipKeyPaths) Sets the prefetching key paths to override those in the underlying fetch spec.
void	setQualifier(EOQualifier qualifier) 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(NSArray<EOSortOrdering> sortOrderings) Overridden to preserve the selected objects.
boolean	shouldRememberRowCount()
protected void	updateBatchCount()
void	updateDisplayedObjects()

Methods inherited from class er.extensions.appserver.ERXDisplayGroup

addToSelection, addToSelection, allObjects, allQualifierOperators, clearExtraQualifiers, displayNextBatch, displayPreviousBatch, indexOfFirstDisplayedObject, indexOfLastDisplayedObject, qualifierForKey, qualifierFromQueryValues, removeFromSelection, removeFromSelection, 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 NSArray<T> _displayedObjects

cache for the displayed objects

_isBatching

protected Boolean _isBatching

cache batching flag

_prefetchingRelationshipKeyPaths

protected NSArray<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 Object decodeWithKeyValueUnarchiver(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(EODataSource datasource)

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

Overrides:

setDataSource in class ERXDisplayGroup<T>

Parameters:

datasource - the EODataSource to use

batchCount

public int batchCount()

Overridden to return the pre-calculated number of batches.

Overrides:

batchCount in class WODisplayGroup

Returns:

the number of batches to display

setCurrentBatchIndex

public void setCurrentBatchIndex(int index)

Overridden to clear out our array of fetched objects.

Overrides:

setCurrentBatchIndex in class WODisplayGroup

Parameters:

index - the index of the batch to display

setNumberOfObjectsPerBatch

public void setNumberOfObjectsPerBatch(int count)

Overridden to clear out our array of fetched objects.

Overrides:

setNumberOfObjectsPerBatch in class ERXDisplayGroup<T>

Parameters:

count - the maximum number of objects to display per batch

displayedObjects

public 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 displayed.

hasMultipleBatches

public boolean hasMultipleBatches()

Overridden to refetchIfNecessary() first to ensure we get a correct result in cases where this is called before displayedObjects().

Overrides:

hasMultipleBatches in class WODisplayGroup

Returns:

true if batchCount is greater than 1, false otherwise

filteredObjects

public NSArray<T> filteredObjects()

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

Overrides:

filteredObjects in class ERXDisplayGroup<T>

Returns:

filtered objects

setQualifier

public void setQualifier(EOQualifier qualifier)

Overridden to trigger a refetch.

Overrides:

setQualifier in class ERXDisplayGroup<T>

Parameters:

qualifier - the qualifier for the display group

setSortOrderings

public void setSortOrderings(NSArray<EOSortOrdering> sortOrderings)

Overridden to preserve the selected objects.

Overrides:

setSortOrderings in class ERXDisplayGroup<T>

Parameters:

sortOrderings - the proposed EOSortOrdering objects

setPrefetchingRelationshipKeyPaths

public void setPrefetchingRelationshipKeyPaths(NSArray<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

setPrefetchingRelationshipKeyPaths

public void setPrefetchingRelationshipKeyPaths(ERXKey<?>... 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 NSArray<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 EOFetchSpecification fetchSpecification()

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

Returns:

the fetch specification

rowCount

public int rowCount()

Utility to get at the number of rows when batching.

Returns:

number of total rows

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 NSArray<T> objectsInRange(int start,
                                    int end)

Utility to fetch the object in a given range.

Parameters:

start - start index of the range

end - end index of the range

Returns:

array of object in the given range

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(NSArray objects)

Overridden to update the batch count.

Overrides:

setObjectArray in class WODisplayGroup

Parameters:

objects - the object array to set

fetch

public Object fetch()

Overridden to fetch only within displayed limits.

Overrides:

fetch in class ERXDisplayGroup<T>

Returns:

null to force the page to reload

updateDisplayedObjects

public void updateDisplayedObjects()

Overrides:

updateDisplayedObjects in class WODisplayGroup

selectFilteredObjects

public 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>

Returns:

null to force the page to reload