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WODisplayGroup Delegate


Adopted by: WODisplayGroup delegate objects
Declared in: WebObjects/WODisplayGroup.h


Protocol Description

WODisplayGroup offers a number of methods for its delegate to implement; if the delegate does implement them, the WODisplayGroup instances invoke them as appropriate. There are methods that inform the delegate that the EODisplayGroup has fetched, created an object (or failed to create one), inserted or deleted an object, changed the selection, or set a value for a property. There are also methods that request permission from the delegate to perform most of these same actions. The delegate can return YES to permit the action or NO to deny it. See each method's description for more information.



Instance Methods


displayGroup:createObjectFailedForDataSource:

- (void)displayGroup:(WODisplayGroup *)aDisplayGroup createObjectFailedForDataSource:(id)aDataSource

Invoked from insertObjectAtIndex: to inform the delegate that aDisplayGroup has failed to create a new object for aDataSource. If the delegate doesn't implement this method, the WODisplayGroup fails silently.

displayGroupDidChangeDataSource:

- (void)displayGroupDidChangeDataSource:(WODisplayGroup *)aDisplayGroup

Informs the delegate that aDisplayGroup's EODataSource (defined in the EOControl framework) has changed.

displayGroupDidChangeSelectedObjects:

- (void)displayGroupDidChangeSelectedObjects:(WODisplayGroup *)aDisplayGroup

Informs the delegate that aDisplayGroup's selected objects have changed, regardless of whether the selection indexes have changed.

displayGroupDidChangeSelection:

- (void)displayGroupDidChangeSelection:(WODisplayGroup *)aDisplayGroup

Informs the delegate that aDisplayGroup's selection has changed.

displayGroup:didDeleteObject:

- (void)displayGroup:(WODisplayGroup *)aDisplayGroup didDeleteObject:(id)anObject

Informs the delegate that aDisplayGroup has deleted anObject.

displayGroup:didFetchObjects:

- (void)displayGroup:(WODisplayGroup *)aDisplayGroup didFetchObjects:(NSArray *)objects

Informs the delegate that aDisplayGroup has fetched objects.

displayGroup:didInsertObject:

- (void)displayGroup:(WODisplayGroup *)aDisplayGroup didInsertObject:(id)anObject

Informs the delegate that aDisplayGroup has inserted anObject.

displayGroup:didSetValue:forObject:key:

- (void)displayGroup:(WODisplayGroup *)aDisplayGroup didSetValue:(id)value forObject:(id)anObject key:(NSString *)key

Informs the delegate that aDisplayGroup has altered a property value of anObject. key identifies the property, and value is its new value.

displayGroup:displayArrayForObjects:

- (NSArray *)displayGroup:(WODisplayGroup *)aDisplayGroup displayArrayForObjects:(NSArray *)objects

Invoked from updateDisplayedObjects, this method allows the delegate to filter and sort aDisplayGroup's array of objects to limit which ones get displayed. objects contains all of aDisplayGroup's objects. The delegate should filter any objects that shouldn't be shown and sort the remainder, returning a new array containing this group of objects. You can use the NSArray methods filteredArrayUsingQualifier: and sortedArrayUsingKeyOrderingArray: to create the new array.

If the delegate doesn't implement this method, the WODisplayGroup uses its own qualifier and sort ordering to update the displayed objects array.

See Also: - displayedObjects, - qualifier, - sortOrderings


displayGroup:shouldChangeSelectionToIndexes:

- (BOOL)displayGroup:(WODisplayGroup *)aDisplayGroup shouldChangeSelectionToIndexes:(NSArray *)newIndexes

Allows the delegate to prevent a change in selection by aDisplayGroup. newIndexes is the proposed new selection. If the delegate returns YES, the selection changes; if the delegate returns NO, the selection remains as it is.

displayGroup:shouldDeleteObject:

- (BOOL)displayGroup:(WODisplayGroup *)aDisplayGroup shouldDeleteObject:(id)anObject

Allows the delegate to prevent aDisplayGroup from deleting anObject. If the delegate returns YES, anObject is deleted; if the delegate returns NO, the deletion is abandoned.

displayGroupShouldFetch:

- (BOOL)displayGroupShouldFetch:(WODisplayGroup *)aDisplayGroup

Allows the delegate to prevent aDisplayGroup from fetching. If the delegate returns YES, aDisplayGroup performs the fetch; if the delegate returns NO, aDisplayGroup abandons the fetch.

displayGroup:shouldInsertObject:atIndex:

- (BOOL)displayGroup:(WODisplayGroup *)aDisplayGroup shouldInsertObject:(id)anObject atIndex:(unsigned int)anIndex

Allows the delegate to prevent redisplay from inserting anObject at anIndex. If the delegate returns YES, anObject is inserted; if the delegate returns NO, the insertion is abandoned.

displayGroup:shouldRedisplayForChangesInEditingContext:

- (BOOL)displayGroup:(WODisplayGroup *)aDisplayGroup shouldRedisplayForEditingContextChangeNotification:(NSNotification *)aNotification

Invoked whenever aDisplayGroup receives an EOObjectsChangedInEditingContextNotification, this method allows the delegate to suppress redisplay based on the nature of the change that has occurred. If the delegate returns YES, aDisplayGroup redisplays; if it returns NO, aDisplayGroup doesn't.

See Also: - redisplay


displayGroup:shouldRefetchForInvalidatedAllObjectsNotification:

- (BOOL)displayGroup:(WODisplayGroup *)aDisplayGroup shouldRefetchForInvalidatedAllObjectsNotification:(NSNotification *)aNotification

Invoked whenever aDisplayGroup receives an EOInvalidatedAllObjectsInStoreNotification, this method allows the delegate to suppress the refetching of the invalidated objects. If the delegate returns YES, aDisplayGroup immediately fetches its objects. If the delegate returns NO, aDisplayGroup doesn't immediately fetch, instead delaying until absolutely necessary.

See Also: - redisplay



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