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EODisplayGroup

Inherits from:
NSObject (Yellow Box)Object (Java Client)

Conforms to:
NSCoding

NSObject (NSObject)

Declared in:
EOInterface/EODisplayGroup.h

Class at a Glance

An EODisplayGroup collects an array of objects from an EODataSource, and works with a group of EOAssociation objects to display and edit the properties of those objects.

Principal Attributes

Array of objects supplied by an EODataSource
EOQualifier and EOSortOrderings to filter the objects for display
Array of selection indexes
Delegate

Commonly Used Methods

- allObjects	Returns all objects in the EODisplayGroup.
- displayedObjects	Returns the subset of all objects made available for display.
- selectedObjects	Returns the selected objects.
- setQualifier:	Sets a filter that limits the objects displayed.
- setSortOrderings:	Sets the ordering used to sort the objects.
- updateDisplayedObjects	Filters, sorts, and redisplays the objects.
- insertObjectAtIndex:	Creates a new object and inserts it into the EODataSource.

Class Description

An EODisplayGroup is the basic user interface manager for an Enterprise Objects Framework or Java Client application. It collects objects from an EODataSource, filters and sorts them, and maintains a selection in the filtered subset. It interacts with user interface objects and other display objects through EOAssociations, which bind the values of objects to various aspects of the display objects.

An EODisplayGroup manipulates its EODataSource by sending it fetchObjects, insertObject:, and other messages, and registers itself as an editor and message handler of the EODataSource's EOEditingContext. The EOEditingContext allows the EODisplayGroup to intercede in certain operations, as described in the EOEditors and EOMessageHandlers informal protocol specifications (both protocols are defined in EOControl). EODisplayGroup implements all the methods of these informal protocols; see their specifications for more information.

Most of an EODisplayGroup's interactions are with its associations, its EODataSource, and its EOEditingContext. See the EOAssociation, EODataSource, and EOEditingContext class specifications for more information on these interactions.

Creating an EODisplayGroup

You create most EODisplayGroups in Interface Builder, by dragging an entity icon from the EOModeler application, which creates an EODisplayGroup with an EODatabaseDataSource (EODistributedDataSource, for Java Client applications), or by dragging an EODisplayGroup with no EODataSource from the EOPalette. EODisplayGroups with EODataSources operate independent of other EODisplayGroups, while those without EODataSources must be set up in a master-detail association with another EODisplayGroup.

To create an EODisplayGroup programmatically, simply initialize it and set its EODataSource:

EODataSource *myDataSource;    /* Assume this exists. */
EODisplayGroup *myDisplayGroup;

myDisplayGroup = [[EODisplayGroup alloc] init];
[myDisplayGroup setDataSource:myDataSource];

After creating the EODisplayGroup, you can add associations as described in the EOAssociation class specification.

Getting Objects

Since an EODisplayGroup isn't much use without objects to manage, the first thing you do with an EODisplayGroup is send it a fetch message. You can use the basic fetch method; the fetch: action method, which can be invoked by a control in the EODisplayGroup's nib file; or you can configure the EODisplayGroup in Interface Builder to fetch automatically when its nib file is loaded. These methods all ask the EODisplayGroup's EODataSource to fetch from its persistent store with a fetchObjects message.

Filtering and Sorting

An EODisplayGroup's fetched objects are available through its allObjects method. These objects are treated only as candidates for display, however. The array of objects actually displayed is filtered and sorted by the EODisplayGroup's delegate, or by a qualifier and sort ordering array. You set the qualifier and sort orderings using the setQualifier: and setSortOrderings: methods. The displayedObjects method returns this filtered and sorted array; index arguments to other EODisplayGroup methods are defined in terms of this array.

If the EODisplayGroup has a delegate that responds to displayGroup:displayArrayForObjects:, it invokes this method rather than using its own qualifier and sort ordering array. The delegate is then responsible for filtering the objects and returning a sorted array. If the delegate only needs to perform one of these steps, it can get the qualifier or sort orderings from the EODisplayGroup and apply either itself using the NSArray methods filteredArrayUsingQualifier: and sortedArrayUsingKeyOrderArray:, which are added by the control layer.

If you change the qualifier or sort ordering, or alter the delegate in a way that changes how it filters and sorts the EODisplayGroup's objects, you can send updateDisplayedObjects to the EODisplayGroup to get it to refilter and resort its objects. Note that this doesn't cause the EODisplayGroup to refetch.

Changing and Examining the Selection

An EODisplayGroup keeps a selection in terms of indexes into the array of displayed objects. EOAssociations that display values for multiple objects are responsible for updating the selection in their EODisplayGroups according to user actions on their display objects. This is typically done with the setSelectionIndexes: method. Other methods available for indirect manipulation of the selection are the action methods selectNext and selectPrevious, as well as selectObjectsIdenticalTo: and selectObjectsIdenticalTo:.

To get the selection, you can use the selectionIndexes method, which returns an array of NSNumbers, or selectedObjects, which returns an array containing the selected objects themselves. Another method, selectedObject, returns the first selected object if there is one.

The Delegate

EODisplayGroup offers a number of methods for its delegate to implement; if the delegate does, it invokes them as appropriate. Besides the aforementioned displayGroup:displayArrayForObjects:, 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. For more information, see each method's description in the EODisplayGroup Delegate informal protocol specification.

Methods for Use by EOAssociations

While most of your application code interacts with objects directly, EODisplayGroup also defines methods for its associations to access properties of individual objects without having to know anything about which methods they implement. Accessing properties through the EODisplayGroup offers associations the benefit of automatic validation, as well.

Associations access objects by index into the displayed objects array, or by object identifier. valueForObjectAtIndex:key: returns the value of a named property for the object at a given index, and setValue:forObjectAtIndex:key: sets it. Similarly, valueForObject:key: and setValue:forObject:key:access the objects by object identifier. EOAssociations can also get and set values for the first object in the selection using selectedObjectValueForKey: and setSelectedObjectValue:forKey:.

Adopted Protocols

NSCoding
- encodeWithCoder:

- initWithCoder:

Method Types

Creating instances

- init

Configuring behavior

- defaultStringMatchFormat

- defaultStringMatchOperator

- fetchesOnLoad

- queryBindingValues

- queryOperatorValues

- selectsFirstObjectAfterFetch

- setDefaultStringMatchFormat:

- setDefaultStringMatchOperator:

- setFetchesOnLoad:

- setQueryBindingValues:

- setQueryOperatorValues:

- setSelectsFirstObjectAfterFetch:

- setUsesOptimisticRefresh:

- setValidatesChangesImmediately:

- usesOptimisticRefresh

- validatesChangesImmediately

Setting the data source

- setDataSource:

- dataSource

Setting the qualifier and sort ordering

- setQualifier:

- qualifier

- setSortOrderings:

- sortOrderings

Managing queries

- qualifierFromQueryValues

- setEqualToQueryValues:

- equalToQueryValues

- setGreaterThanQueryValues:

- greaterThanQueryValues

- setLessThanQueryValues:

- lessThanQueryValues

- qualifyDisplayGroup

- qualifyDisplayGroup:

- qualifyDataSource

- qualifyDataSource:

- enterQueryMode:

- inQueryMode

- setInQueryMode:

- enabledToSetSelectedObjectValueForKey:

Fetching objects from the data source

- fetch

- fetch:

Getting the objects

- allObjects

- displayedObjects

Updating display of values

- redisplay

- updateDisplayedObjects

Setting the objects

- setObjectArray:

Changing the selection

- setSelectionIndexes:

- selectObjectsIdenticalTo:

- selectObjectsIdenticalTo:selectFirstOnNoMatch:

- selectObject:

- clearSelection

- selectNext

- selectNext:

- selectPrevious

- selectPrevious:

Examining the selection

- selectionIndexes

- selectedObject

- selectedObjects

Inserting and deleting objects

- delete:

- deleteObjectAtIndex:

- deleteSelection

- insert:

- insertedObjectDefaultValues (Yellow Box applications only)

- insertObjectAtIndex:

- insertObject:atIndex:

- setInsertedObjectDefaultValues:(Yellow Box applications only)

Adding keys

- setLocalKeys:

- localKeys

Getting the associations

- observingAssociations

Setting the delegate

- setDelegate:

- delegate

Changing values from associations

- setSelectedObjectValue:forKey:

- selectedObjectValueForKey:

- setValue:forObject:key:

- valueForObject:key:

- setValue:forObjectAtIndex:key:

- valueForObjectAtIndex:key:

Editing by associations

- associationDidBeginEditing:

- association:failedToValidateValue:forKey:object:errorDescription:

- associationDidEndEditing:

- editingAssociation

- endEditing

Querying changes for associations

- contentsChanged

- selectionChanged

- updatedObjectIndex

Interacting with the EOEditingContext

- editorHasChangesForEditingContext:

- editingContextWillSaveChanges:

- editingContext:presentErrorMessage:

Class Methods

globalDefaultForValidatesChangesImmediately

+ (BOOL)globalDefaultForValidatesChangesImmediately

Returns YES if the default behavior for new display group instances is to immediately handle validation errors, or NO if the default behavior leaves errors for the EOEditingContext to handle when saving changes.

See Also: - validatesChangesImmediately

globalDefaultStringMatchFormat

+ (NSString *)globalDefaultStringMatchFormat

Returns the default string match format string used by display group instances.

See Also: - defaultStringMatchFormat

globalDefaultStringMatchOperator

+ (NSString *)globalDefaultStringMatchOperator

Returns the default string match operator used by display group instances.

See Also: - defaultStringMatchOperator

setGlobalDefaultForValidatesChangesImmediately:

+ (void)setGlobalDefaultForValidatesChangesImmediately:(BOOL)flag

Sets the default behavior display group instances use when they encounter a validation error. If flag is YES, the default behavior is for display groups to immediately present an attention panel indicating a validation error. If flag is NO, the default behavior if for display groups to leave validation errors to be handled when changes are saved. By default, display groups don't validate changes immediately.

See Also: - saveChanges (EOEditingContext), - setValidatesChangesImmediately:

setGlobalDefaultStringMatchFormat:

+ (void)setGlobalDefaultStringMatchFormat:(NSString *)format

Sets the default string match format to be used by display group instances. The default format string for pattern matching is "%@*".

See Also: - setDefaultStringMatchFormat:

setGlobalDefaultStringMatchOperator:

+ (void)setGlobalDefaultStringMatchOperator:(NSString *)op

Sets the default string match operator to be used by display group instances. The default operator is case insensitive like.

See Also: - setDefaultStringMatchOperator:

Instance Methods

allObjects

- (NSArray *)allObjects

Returns all of the objects collected by the receiver.

See Also: - displayedObjects, - fetch

associationDidBeginEditing:

- (void)associationDidBeginEditing:(EOAssociation *)anAssociation

Invoked by anAssociation when its display object begins editing to record that EOAssociation as the editing association.

associationDidEndEditing:

- (void)associationDidEndEditing:(EOAssociation *)anAssociation

Invoked by anAssociation to clear the editing association. If anAssociation is the receiver's editing association, clears the editing association. Otherwise does nothing.

association:failedToValidateValue:forKey:object:errorDescription:

- (BOOL)association:(EOAssociation *)anAssociation failedToValidateValue:(NSString *)value forKey:(NSString *)key object:(id)anObject errorDescription:(NSString *)errorDescription

Invoked by anAssociation from its shouldEndEditingForAspect:invalidInput:errorDescription:index: method to let the receiver handle a validation error. This method opens an attention panel with errorDescription as the message and returns NO.

clearSelection

- (BOOL)clearSelection

Invokes setSelectionIndexes: to clear the selection, returning YES on success and NO on failure.

contentsChanged

- (BOOL)contentsChanged

Returns YES if the receiver's array of objects has changed and not all observers have been notified, NO otherwise. EOAssociations use this in their subjectChanged methods to determine what they need to update.

dataSource

- (EODataSource *)dataSource

Returns the receiver's EODataSource.

See Also: - setDataSource:

defaultStringMatchFormat

- (NSString *)defaultStringMatchFormat

Returns the format string that specifies how pattern matching will be performed on string values in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues). If a key in the queryMatch dictionary does not have an associated operator in the queryOperatorValues dictionary, then its value is matched using pattern matching, and the format string returned by this method specifies how it will be matched.

defaultStringMatchOperator

- (NSString *)defaultStringMatchOperator

Returns the operator used to perform pattern matching for string values in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues). If a key in one of the query dictionaries does not have an associated operator in the queryOperatorValues dictionary, then the operator returned by this method is used to perform pattern matching.

delegate

- (id)delegate

Returns the receiver's delegate.

See Also: - setDelegate:

delete:

- (void)delete:(id)sender

This action method invokes deleteSelection.

deleteObjectAtIndex:

- (BOOL)deleteObjectAtIndex:(unsigned int)index

Attempts to delete the object at index, returning YES if successful and NO if not. Checks with the delegate using displayGroup:shouldDeleteObject:. If the delegate returns NO, this method fails and returns NO. If successful, sends the delegate a displayGroup:didDeleteObject: message.

This method performs the delete by sending deleteObject: to the EODataSource. If that message raises an exception, this method fails and returns NO.

deleteSelection

- (BOOL)deleteSelection

Attempts to delete the selected objects, returning YES if successful and NO if not.

displayedObjects

- (NSArray *)displayedObjects

Returns the objects that should be displayed or otherwise made available to the user, as filtered by the receiver's delegate or by its qualifier and sort ordering.

editingAssociation

- (EOAssociation *)editingAssociation

Returns the EOAssociation editing a value if there is one, NO if there isn't.

editingContext:presentErrorMessage:

- (void)editingContext:(EOEditingContext *)anEditingContext presentErrorMessage:(NSString *)errorMessage

Invoked by anEditingContext as part of the EOMessageHandlers informal protocol, this method presents an attention panel with errorMessage as the message to display.

editingContextWillSaveChanges:

- (void)editingContextWillSaveChanges:(EOEditingContext *)anEditingContext

Invoked by anEditingContext in its saveChanges method as part of the EOEditors informal protocol, this method allows the EODisplayGroup to prohibit a save operation. EODisplayGroup's implementation of this method invokes endEditing, and raises an NSInternalInconsistencyException if it returns NO. Thus, if there's an association that refuses to end editing, anEditingContext doesn't save changes.

editorHasChangesForEditingContext:

- (BOOL)editorHasChangesForEditingContext:(EOEditingContext *)anEditingContext

Invoked by anEditingContext as part of the EOEditors informal protocol, this method returns NO if any association is editing, YES otherwise.

enabledToSetSelectedObjectValueForKey:

- (BOOL)enabledToSetSelectedObjectValueForKey:(NSString *)key

Returns YES to indicate that a single value association (such as an EOControlAssociation for a NSTextField) should be enabled for setting key, NO otherwise. Normally this is the case if the receiver has a selected object. However, if key is a special query key (for example, "@query=.name"), then the control should be enabled even without a selected object.

endEditing

- (BOOL)endEditing

Attempts to end any editing taking place. If there's no editing association or if the editing association responds YES to an endEditing message, returns YES. Otherwise returns NO.

See Also: - editingAssociation

enterQueryMode:

- (void)enterQueryMode:(id)sender

This action method invokes setInQueryMode: with an argument of YES.

equalToQueryValues

- (NSDictionary *)equalToQueryValues

Returns the receiver's dictionary of equalTo query values. This dictionary is typically manipulated by associations bound to keys of the form @query=.propertyName. The qualifierFromQueryValues method uses this dictionary along with the lessThan and greaterThan dictionaries to construct qualifiers.

fetch

- (BOOL)fetch

Attempts to fetch objects from the EODataSource, returning YES on success and NO on failure.

Before fetching, invokes endEditing and sends displayGroupShouldFetch: to the delegate, returning NO if either of these methods does. If both return YES, sends a fetchObjects message to the receiver's EODataSource to replace the object array, and if successful sends the delegate a displayGroup:didFetchObjects: message.

fetch:

- (void)fetch:(id)sender

This action method invokes fetch.

fetchesOnLoad

- (BOOL)fetchesOnLoad

Returns YES if the receiver fetches automatically after being loaded from a nib file, NO if it must be told explicitly to fetch. The default is NO. You can set this behavior in Interface Builder using the Inspector panel.

See Also: - fetch, - setFetchesOnLoad:

greaterThanQueryValues

- (NSDictionary *)greaterThanQueryValues

Returns the receiver's dictionary of greaterThan query values. This dictionary is typically manipulated by associations bound to keys of the form @query>.propertyName. The qualifierFromQueryValues method uses this dictionary along with the lessThan and equalTo dictionaries to construct qualifiers.

init

- (id)init

Initializes a newly allocated EODisplayGroup. The new display group then needs to have an EODataSource set with setDataSource:. This is the designated initializer for the EODisplayGroup class. Returns self.

See Also: - bindAspect:displayGroup:key: (EOAssociation)

inQueryMode

- (BOOL)inQueryMode

Returns YES to indicate that the receiver is in query mode, NO otherwise. In query mode, user interface controls that normally display values become empty, allowing users to type queries directly into them (this is also known as a "Query By Example" interface). In effect, the receiver's "displayedObjects" are replaced with an empty equalTo query values dictionary. When qualifyDisplayGroup or qualifyDataSource is subsequently invoked, the query is performed and the display reverts to displaying values-this time, the objects returned by the query.

See Also: - setInQueryMode:, - enterQueryMode:

insert:

- (void)insert:(id)sender

This action method invokes insertObjectAtIndex: with an index just past the first index in the selection, or 0 if there's no selection.

insertedObjectDefaultValues

- (NSDictionary *)insertedObjectDefaultValues

Returns the default values to be used for newly inserted objects. The keys into the dictionary are the properties of the entity that the display group manages. If the dictionary returned by this method is empty, the insert... method adds an object that is initially empty. Because the object is empty, the display group has no value to display on the HTML page for that object, meaning that there is nothing for the user to select and modify. Use the setInsertedObjectDefaultValues: method to set up a default value so that there is something to display on the page.

insertObjectAtIndex:

- (id)insertObjectAtIndex:(unsigned int)anIndex

Asks the receiver's EODataSource to create a new object by sending it a createObject message, then inserts the new object using insertObject:atIndex:. The EODataSource createObject method has the effect of inserting the object into the EOEditingContext.

If a new object can't be created, this method sends the delegate a displayGroup:createObjectFailedForDataSource: message or, if the delegate doesn't respond, opens an attention panel to inform the user of the error.

See Also: - insert:

insertObject:atIndex:

- (void)insertObject:(id)anObject atIndex:(unsigned int)index

Inserts anObject into the receiver's EODataSource and displayedObjects array at index, if possible. This method checks with the delegate before actually inserting, using displayGroup:shouldInsertObject:atIndex:. If the delegate refuses, anObject isn't inserted. After successfully inserting the object, this method informs the delegate with a displayGroup:didInsertObject: message, and selects the newly inserted object. Raises an NSRangeException if index is out of bounds.

Unlike the insertObjectAtIndex: method, this method does not insert the object into the EOEditingContext. If you use this method, you're responsible for inserting the object into the EOEditingContext yourself.

lessThanQueryValues

- (NSDictionary *)lessThanQueryValues

Returns the receiver's dictionary of lessThan query values. This dictionary is typically manipulated by associations bound to keys of the form @query<.propertyName. The qualifierFromQueryValues method uses this dictionary along with the greaterThan and equalTo dictionaries to construct qualifiers.

localKeys

- (NSArray *)localKeys

Returns the additional keys that EOAssociations can be bound to. An EODisplayGroup's basic keys are typically those of the attributes and relationships of its objects, as defined by their EOClassDescription through an EOEntity in the model. Local keys are typically used to form associations with key paths, with arbitrary methods of objects, or with properties of objects not associated with an EOEntity. Interface Builder allows the user to add and remove local keys in the EODisplayGroup Attributes Inspector panel.

See Also: - setLocalKeys:

observingAssociations

- (NSArray *)observingAssociations

Returns all EOAssociations that observe the receiver's objects.

qualifier

- (EOQualifier *)qualifier

Returns the receiver's qualifier, which it uses to filter its array of objects for display when the delegate doesn't do so itself.

qualifierFromQueryValues

- (EOQualifier *)qualifierFromQueryValues

Builds a qualifier constructed from entries in the three query dictionaries: equalTo, greaterThan, and lessThan. These, in turn, are typically manipulated by associations bound to keys of the form @query=.firstName, @query>.budget, @query<.budget.

qualifyDataSource

- (void)qualifyDataSource

Takes the result of qualifierFromQueryValues and applies to the receiver's data source. The receiver then sends itself a fetch message. If the receiver is in query mode, query mode is exited. This method differs from qualifyDisplayGroup as follows: whereas qualifyDisplayGroup performs in-memory filtering of already fetched objects, qualifyDataSource triggers a new qualified fetch against the database.

qualifyDataSource:

- (void)qualifyDataSource:(id)sender

This action method invokes qualifyDataSource.

qualifyDisplayGroup

- (void)qualifyDisplayGroup

Takes the result of qualifierFromQueryValues and applies to the receiver using setQualifier:. The method updateDisplayedObjects is invoked to refresh the display. If the receiver is in query mode, query mode is exited.

qualifyDisplayGroup:

- (void)qualifyDisplayGroup:(id)sender

This action method invokes qualifyDisplayGroup:.

queryBindingValues

- (NSDictionary *)queryBindingValues

Returns a dictionary containing the actual values that the user wants to query upon. You use this method to perform a query stored in the model file. Bind keys in this dictionary to elements on your component that specify query values, then pass this dictionary to the fetch specification that performs the fetch.

queryOperatorValues

- (NSDictionary *)queryOperatorValues

Returns a dictionary of operators to use on items in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues). If a key in a query dictionary also exists in queryOperatorValues, that operator for that key is used.

See Also: - qualifierFromQueryValues

redisplay

- (void)redisplay

Notifies all observing associations to redisplay their values.

See Also: - observingAssociations

selectedObject

- (id)selectedObject

Returns the first selected object in the displayed objects array, or nil if there's no such object.

See Also: - displayedObjects, - selectionIndexes

selectedObjects

- (NSArray *)selectedObjects

Returns the objects selected in the receiver's displayed objects array.

See Also: - displayedObjects, - selectionIndexes

selectedObjectValueForKey:

- (id)selectedObjectValueForKey:(NSString *)key

Returns the value corresponding to key for the first selected object in the receiver's displayed objects array, or nil if exactly one object isn't selected.

See Also: - valueForObjectAtIndex:key:

selectionChanged

- (BOOL)selectionChanged

Returns YES if the selection has changed and not all observers have been notified, NO otherwise. EOAssociations use this in their subjectChanged methods to determine what they need to update.

See Also: - contentsChanged

selectionIndexes

- (NSArray *)selectionIndexes

Returns the indexes of the receiver's selected objects as NSNumbers, in terms of its displayed objects array.

selectNext

- (BOOL)selectNext

Attempts to select the object just after the currently selected one, returning YES if successful and NO if not. The selection is altered in this way:

If there are no objects, does nothing and returns NO.
If there's no selection, selects the object at index zero and returns YES.
If the first selected object is the last object in the displayed objects array, selects the first object and returns YES.
Otherwise selects the object after the first selected object.

selectNext:

- (void)selectNext:(id)sender

This action method invokes selectNext.

selectObject:

- (BOOL)selectObject:(id)anObject

Returns YES to indicate that the receiver has found and selected anObject, NO if it can't find a match for anObject (in which case it clears the selection). The selection is performed on the receiver's displayedObjects, not on allObjects.

selectObjectsIdenticalTo:

- (BOOL)selectObjectsIdenticalTo:(NSArray *)objects

Attempts to select the objects in the receiver's displayed objects array whose ids are equal to those of objects, returning YES if successful and NO otherwise.

selectObjectsIdenticalTo:selectFirstOnNoMatch:

- (BOOL)selectObjectsIdenticalTo:(NSArray *)objects selectFirstOnNoMatch:(BOOL)flag

Selects the objects in the receiver's displayed objects array whose ids are equal to those of objects, returning YES if successful and NO otherwise. If no objects in the displayed objects array match objects and flag is YES, attempts to select the first object in the displayed objects array.

See Also: - setSelectionIndexes:

selectPrevious

- (BOOL)selectPrevious

Attempts to select the object just before the presently selected one, returning YES if successful and NO if not. The selection is altered in this way:

If there are no objects, does nothing and returns NO.
If there's no selection, selects the object at index zero and returns YES.
If the first selected object is at index zero, selects the last object and returns YES.
Otherwise selects the object before the first selected object.

selectPrevious:

- (void)selectPrevious:(id)sender

This action method invokes selectPrevious.

See Also: - selectNext:, - redisplay

selectsFirstObjectAfterFetch

- (BOOL)selectsFirstObjectAfterFetch

Returns YES if the receiver automatically selects its first displayed object after a fetch if there was no selection, NO if it leaves an empty selection as-is.

setDataSource:

- (void)setDataSource:(EODataSource *)aDataSource

Sets the receiver's EODataSource to aDataSource. In the process, it performs these actions:

Unregisters self as an editor and message handler for the previous EODataSource's EOEditingContext, if necessary, and registers self with aDataSource's editing context. If the new editing context already has a message handler, however, the receiver doesn't assume that role.
Registers self for EOObjectsChangedInEditingContextNotification and EOInvalidatedAllObjectsInStoreNotification from the new editing context.
Clears the receiver's array of objects.
Sends displayGroupDidChangeDataSource: to the delegate if there is one.

See Also: - dataSource

setDefaultStringMatchFormat:

- (void)setDefaultStringMatchFormat:(NSString *)format

Sets how pattern matching will be performed on NSString values in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues). This format is used for query dictionary properties that have NSString values and that do not have an associated entry in the queryOperatorValues dictionary. In these cases, the value is matched using pattern matching and format specifies how it will be matched.

The default format string for pattern matching is "%@*" which means that the string value in the queryMatch dictionary is used as a prefix. For example, if the query dictionary contains a value "Jo" for the key "Name", the query returns all records whose name values begin with "Jo".

setDefaultStringMatchOperator:

- (void)setDefaultStringMatchOperator:(NSString *)matchOperator

Sets the operator used to perform pattern matching for NSString values in the queryMatch dictionary. This operator is used for properties listed in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues) that have NSString values and that do not have an associated entry in the queryOperatorValues dictionary. In these cases, the operator matchOperator is used to perform pattern matching.

The default value for the query match operator is caseInsensitiveLike, which means that the query does not consider case when matching letters. The other possible value for this operator is like, which matches the case of the letters exactly.

setDelegate:

- (void)setDelegate:(id)anObject

Sets the receiver's delegate to anObject, without retaining it.

See Also: - delegate

setEqualToQueryValues:

- (void)setEqualToQueryValues:(NSDictionary *)values

Sets to values the receiver's dictionary of equalTo query values. The qualifierFromQueryValues method uses this dictionary along with the lessThan and greaterThan dictionaries to construct qualifiers.

setFetchesOnLoad:

- (void)setFetchesOnLoad:(BOOL)flag

Controls whether the receiver automatically fetches its objects after being loaded from a nib file. If flag is YES it does; if flag is NO the receiver must be told explicitly to fetch. The default is NO. You can also set this behavior in Interface Builder using the Inspector panel.

See Also: - fetch, - fetchesOnLoad

setGreaterThanQueryValues:

- (void)setGreaterThanQueryValues:(NSDictionary *)values

Sets to values the receiver's dictionary of greaterThan query values. The qualifierFromQueryValues method uses this dictionary along with the lessThan and equalTo dictionaries to construct qualifiers.

setInQueryMode:

- (void)setInQueryMode:(BOOL)flag

Sets according to flag whether the receiver is in query mode.

See Also: - inQueryMode, - enterQueryMode:

setInsertedObjectDefaultValues:

- (void)setInsertedObjectDefaultValues:(NSDictionary *)defaultValues

Sets default values to be used for newly inserted objects. When you use the insert... method to add an object, that object is initially empty. Because the object is empty, there is no value to be displayed on the HTML page, meaning there is nothing for the user to select and modify. You use this method to provide at least one field that can be displayed for the newly inserted object. The possible keys into the dictionary are the properties of the entity managed by this display group. For example, a component that displays a list of movie titles and allows the user to insert new movie titles might contain these statements to ensure that all new objects have something to display as a movie title:

[defaultValues setObject:@"New title" forKey:@"title"];
[movies setInsertedObjectDefaultValues:defaultValues];

See Also: - insertedObjectDefaultValues

setLessThanQueryValues:

- (void)setLessThanQueryValues:(NSDictionary *)values

Sets to values the receiver's dictionary of lessThan query values. The qualifierFromQueryValues method uses this dictionary along with the greaterThan and equalTo dictionaries to construct qualifiers.

setLocalKeys:

- (void)setLocalKeys:(NSArray *)keys

Sets the additional keys to which EOAssociations can be bound to the strings in keys. Instead of invoking this method programmatically, you can use Interface Builder to add and remove local keys in the EODisplayGroup Attributes Inspector panel.

See Also: - localKeys

setObjectArray:

- (void)setObjectArray:(NSArray *)objects

Sets the receiver's objects to objects, regardless of what its EODataSource provides. This method doesn't affect the EODataSource's objects at all; specifically, it results in neither inserts or deletes of objects in the EODataSource. objects should contain objects with the same property names or methods as those accessed by the receiver. This method is used by fetch to set the array of fetched objects; you should rarely need to invoke it directly.

After setting the object array, this method restores as much of the original selection as possible by invoking selectObjectsIdenticalTo:. If there's no match and the receiver selects after fetching, then the first object is selected.

setQualifier:

- (void)setQualifier:(EOQualifier *)aQualifier

Sets the receiver's qualifier to aQualifier. This qualifier is used to filter (in memory) the receiver's array of objects for display when the delegate doesn't do so itself. Use updateDisplayedObjects to apply the qualifier.

If the receiver's delegate responds to displayGroup:displayArrayForObjects:, that method is used instead of the qualifier to filter the objects.

See Also: - displayedObjects, - qualifier, - qualifierFromQueryValues, - setAuxiliaryQualifier: (EODatabaseDataSource in EOAccess)

setQueryBindingValues:

- (void)setQueryBindingValues:(NSDictionary *)values

Sets the dictionary of values that a user wants to query on. You use this method to perform a query stored in the model file. Bind keys in the queryBindingValues dictionary to elements of your component that specify query values.

setQueryOperatorValues:

- (void)setQueryOperatorValues:(NSDictionary *)values

Sets the dictionary of operators to use on items in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues). If a key in a query dictionary also exists in queryOperatorValues, that operator for that key is used.

setSelectedObjectValue:forKey:

- (BOOL)setSelectedObjectValue:(id)value forKey:(NSString *)key

Invokes setValue:forObject:key: with the first selected object, returning YES if successful and NO otherwise. This method should be invoked only by EOAssociation objects to propagate changes from display objects.

setSelectionIndexes:

- (BOOL)setSelectionIndexes:(NSArray *)indexes

Selects the objects at indexes in the receiver's array if possible, returning YES if successful and NO if not (in which case the selection remains unaltered). indexes is an array of NSNumbers. This method is the primitive method for altering the selection; all other such methods invoke this one to make the change.

This method invokes endEditing to wrap up any changes being made by the user. If endEditing returns NO, this method fails and returns NO. This method then checks the delegate with a displayGroup:shouldChangeSelectionToIndexes: message. If the delegate returns NO, this method also fails and returns NO. If the receiver successfully changes the selection, its observers (typically EOAssociations) each receive a subjectChanged message.

setSelectsFirstObjectAfterFetch:

- (void)setSelectsFirstObjectAfterFetch:(BOOL)flag

Controls whether the receiver automatically selects its first displayed object after a fetch when there were no selected objects before the fetch. If flag is YES it does; if flag is NO then no objects are selected. By default, display groups select the first object after a fetch when there was no previous selection.

setSortOrderings:

- (void)setSortOrderings:(NSArray *)orderings

Sets the EOSortOrdering objects that updateDisplayedObjects uses to sort the displayed objects to orderings. Use updateDisplayedObjects to apply the sort orderings.

If the receiver's delegate responds to displayGroup:displayArrayForObjects:, that method is used instead of the sort orderings to order the objects.

See Also: - displayedObjects, - sortOrderings

setUsesOptimisticRefresh:

- (void)setUsesOptimisticRefresh:(BOOL)flag

Controls how the receiver redisplays on changes to objects. If flag is YES it redisplays only when elements of its displayed objects array change; if flag is NO it redisplays on any change in its EOEditingContext. Because changes to other objects can affect the displayed objects (through flattened attributes or custom methods, for example), EODisplayGroups by default use the more pessimistic refresh technique of redisplaying on any change in the EOEditingContext. If you know that none of the EOAssociations for a particular EODisplayGroup display derived values, you can turn on optimistic refresh to reduce redisplay time.

The default is NO. You can also change this setting in Interface Builder's Inspector panel using the Refresh All check box.

See Also: - usesOptimisticRefresh

setValidatesChangesImmediately:

- (void)setValidatesChangesImmediately:(BOOL)flag

Controls the receiver's behavior on encountering a validation error. Whenever an EODisplayGroup sets a value in an object, it sends the object a validateValue:forKey: message, allowing the object to coerce the value's type to a more appropriate one or to return an exception indicating that the value isn't valid. If this method is invoked with a flag of YES, the receiver immediately presents an attention panel indicating the validation error. If this method is invoked with a flag of NO, the receiver leaves validation errors to be handled when changes are saved. By default, display groups don't validate changes immediately.

See Also: - saveChanges (EOEditingContext), - validatesChangesImmediately

setValue:forObject:key:

- (BOOL)setValue:(id)value forObject:(id)anObject key:(NSString *)key

Sets a property of anObject, identified by key, to value. Returns YES if successful and NO otherwise. If a new value is set, sends the delegate a displayGroup:didSetValue:forObject:key: message.

This method should be invoked only by EOAssociation objects to propagate changes from display objects. Other application code should interact with the objects directly.

If the receiver validates changes immediately, it sends anObject a validateValue:forKey: message, returning NO if the object refuses to validate value. Otherwise, validation errors are checked by the EOEditingContext when it attempts to save changes.

setValue:forObjectAtIndex:key:

whose ids Invokes setValue:forObject:key: with the object at index, returning YES if successful and NO otherwise. This method should be invoked only by EOAssociation objects to propagate changes from display objects.

sortOrderings

- (NSArray *)sortOrderings

Returns an array of EOSortOrdering objects that updateDisplayedObjects uses to sort the displayed objects, as returned by the displayedObjects method.

See Also: - setSortOrderings:

updateDisplayedObjects

- (void)updateDisplayedObjects

Recalculates the receiver's displayed objects array and redisplays. If the receiver's delegate responds to displayGroup:displayArrayForObjects:, it's sent this message and the returned array is set as the display group's displayed object. Otherwise, the receiver applies its qualifier and sort ordering to its array of objects. In either case, any objects that were selected before remain selected in the new displayed objects array.

updatedObjectIndex

- (int)updatedObjectIndex

Returns the index in the displayed objects array of the most recently updated object, or -1 if more than one object has changed. The return value is meaningful only when contentsChanged returns YES. EOAssociations can use this method to optimize redisplay of their user interface objects.

usesOptimisticRefresh

- (BOOL)usesOptimisticRefresh

Returns YES if the receiver redisplays only when its displayed objects change, NO if it redisplays on any change in its EOEditingContext.

See Also: - setUsesOptimisticRefresh:

validatesChangesImmediately

- (BOOL)validatesChangesImmediately

Returns YES if the receiver immediately handles validation errors, or NO if it leaves errors for the EOEditingContext to handle when saving changes.

valueForObject:key:

- (id)valueForObject:(id)anObject key:(NSString *)key

Returns anObject's value for the property identified by key.

valueForObjectAtIndex:key:

- (id)valueForObjectAtIndex:(unsigned int)index key:(NSString *)key

Returns the value of the object at index for the property identified by key.

Notifications

EODisplayGroupWillFetchNotification

Posted whenever an EODisplayGroup receives a fetch message. The notification contains:

Notification Object	The EODisplayGroup that received the fetch message.
Userinfo	None