PATH Documentation > WebObjects 4.5 > EOInterface Reference

EODisplayGroup

Inherits from:
(com.apple.client.eointerface) Object
(com.apple.yellow.eointerface) NSObject

Implements:
(com.apple.client.eointerface only) NSDisposable

(com.apple.client.eointerface only) NSInlineObservable

Package:
com.apple.client.eointerface

com.apple.yellow.eointerface

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.
insertNewObjectAtIndex	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 EOEditingContext.Editor and EOEditingContext.MessageHandler interface specifications (both interfaces 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:

EODistributedDataSource dataSource;    /* Assume this exists. */
EODisplayGroup displayGroup;

displayGroup = new EODisplayGroup();
displayGroup.setDataSource(dataSource);

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 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 displayGroupDisplayArrayForObjects, 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 EOQualifier's filteredArrayUsingQualifier and EOSortOrdering's sortedArrayUsingKeyOrderArray methods, 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 displayGroupDisplayArrayForObjects, 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 true to permit the action or false to deny it. For more information, see each method's description in the EODisplayGroup.Delegate interface 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 returns the value of a named property for the object at a given index, and setValueForObjectAtIndex sets it. Similarly, valueForObject and setValueForObjectaccess the objects by object identifier. EOAssociations can also get and set values for the first object in the selection using selectedObjectValueForKey and setSelectedObjectValue.

Constants

(com.apple.client.eointerface only) EODisplayGroup defines String constants for the names of the notifications it posts. For more information, see "Notifications".

Interfaces Implemented

NSInlineObservable (com.apple.client.eointerface only)
observerData

setObserverData

NSDisposable (com.apple.client.eointerface only)
dispose

Method Types

Configuring behavior

defaultStringMatchFormat

defaultStringMatchOperator

fetchesOnLoad

queryBindingValues

queryOperatorValues

selectsFirstObjectAfterFetch

setDefaultStringMatchFormat

setDefaultStringMatchOperator

setFetchesOnLoad

setQueryBindingValues

setQueryOperatorValues

setSelectedObject

setSelectedObjects

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

qualifyDataSource

enterQueryMode

inQueryMode

setInQueryMode

enabledToSetSelectedObjectValueForKey

Fetching objects from the data source

fetch

Getting the objects

allObjects

displayedObjects

Updating display of values

redisplay

updateDisplayedObjects

Setting the objects

setObjectArray

Changing the selection

setSelectionIndexes

selectObjectsIdenticalTo

selectObject

clearSelection

selectNext

selectPrevious

Examining the selection

selectionIndexes

selectedObject

selectedObjects

Adding keys

setLocalKeys

localKeys

Getting the associations

observingAssociations

Setting the delegate

setDelegate

delegate

Changing values from associations

setSelectedObjectValue

selectedObjectValueForKey

setValueForObject

valueForObject

setValueForObjectAtIndex

valueForObjectAtIndex

Editing by associations

associationDidBeginEditing

associationFailedToValidateValue

associationDidEndEditing

editingAssociation

endEditing

Querying changes for associations

contentsChanged

selectionChanged

updatedObjectIndex

Interacting with the EOEditingContext

editorHasChangesForEditingContext

editingContextWillSaveChanges

editingContextPresentErrorMessage

Constructors

EODisplayGroup

public EODisplayGroup()

Creates a new EODisplayGroup. The new display group needs to have an EODataSource set with setDataSource.

See Also: bindAspect (EOAssociation)

Static Methods

globalDefaultForValidatesChangesImmediately

public static boolean globalDefaultForValidatesChangesImmediately()

Returns true if the default behavior for new display group instances is to immediately handle validation errors, or false if the default behavior leaves errors for the EOEditingContext to handle when saving changes.

See Also: validatesChangesImmediately

globalDefaultStringMatchFormat

public static String globalDefaultStringMatchFormat()

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

See Also: defaultStringMatchFormat

globalDefaultStringMatchOperator

public static String globalDefaultStringMatchOperator()

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

See Also: defaultStringMatchOperator

setGlobalDefaultForValidatesChangesImmediately

public static void setGlobalDefaultForValidatesChangesImmediately(boolean flag)

Sets the default behavior display group instances use when they encounter a validation error. If flag is true, the default behavior is for display groups to immediately present an attention panel indicating a validation error. If flag is false, 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

public static void setGlobalDefaultStringMatchFormat(String 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

public static void setGlobalDefaultStringMatchOperator(String 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

public NSArray allObjects()

Returns all of the objects collected by the receiver.

See Also: displayedObjects, fetch

associationDidBeginEditing

public void associationDidBeginEditing(EOAssociation anAssociation)

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

associationDidEndEditing

public 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.

associationFailedToValidateValue

public boolean associationFailedToValidateValue( EOAssociation anAssociation, String value, String key, Object anObject, String errorDescription)

Invoked by anAssociation from its shouldEndEditingAtIndex method to let the receiver handle a validation error. This method opens an attention panel with errorDescription as the message and returns false.

awakeFromNib

public void awakeFromNib()

(com.apple.client.eointerface only) Invoked when the receiver is unarchived from a nib file to prepare it for use in an application. You should never invoke this method directly. Finishes initializing the receiver and updates the display.

See Also: finishInitialization, redisplay

clearSelection

public boolean clearSelection()

Invokes setSelectionIndexes to clear the selection, returning true on success and false on failure.

contentsChanged

public boolean contentsChanged()

Returns true if the receiver's array of objects has changed and not all observers have been notified, false otherwise. EOAssociations use this in their subjectChanged methods to determine what they need to update.

See Also: selectionChanged, updatedObjectIndex

dataSource

public EODataSource dataSource()

Returns the receiver's EODataSource.

See Also: setDataSource

defaultStringMatchFormat

public String 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

public String 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

public Object delegate()

Returns the receiver's delegate.

See Also: setDelegate

delete

public void delete(Object anObject)

(com.apple.client.eointerface only) This action method invokes deleteSelection.

deleteObjectAtIndex

public boolean deleteObjectAtIndex(int index)

Attempts to delete the object at index, returning true if successful and false if not. Checks with the delegate using displayGroupShouldDeleteObject. If the delegate returns false, this method fails and returns false. If successful, sends the delegate a displayGroupDidDeleteObject message.

This method performs the delete by sending deleteObject to the EODataSource. If that message throws an exception, this method fails and returns false.

deleteSelection

public boolean deleteSelection()

Attempts to delete the selected objects, returning true if successful and false if not.

displayedObjects

public 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

public EOAssociation editingAssociation()

Returns the EOAssociation editing a value if there is one, false if there isn't.

editingContextPresentErrorMessage

public void editingContextPresentErrorMessage( EOEditingContext anEditingContext, String errorMessage)

Invoked by anEditingContext as part of the EOEditingContext.MessageHandlers interface, this method presents an attention panel with errorMessage as the message to display.

editingContextShouldContinueFetching

public boolean editingContextShouldContinueFetching( com.apple.client.eocontrol.EOEditingContext anEditingContext,

(com.apple.client.eointerface only) Invoked by anEditingContext as part of the EOEditingContext.MessageHandlers interface, this method presents an attention panel prompting the user about whether or not to continue fetching the current result set.

editingContextWillSaveChanges

public 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 throws an exception if it returns false. Thus, if there's an association that refuses to end editing, anEditingContext doesn't save changes.

editorHasChangesForEditingContext

public boolean editorHasChangesForEditingContext(EOEditingContext anEditingContext)

Invoked by anEditingContext as part of the EOEditors interface, this method returns false if any association is editing, true otherwise.

enabledToSetSelectedObjectValueForKey

public boolean enabledToSetSelectedObjectValueForKey(String key)

Returns true to indicate that a single value association (such as an EOControlAssociation for a NSTextField) should be enabled for setting key, false 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

public boolean endEditing()

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

See Also: editingAssociation

enterQueryMode

public void enterQueryMode(Object sender)

This action method invokes setInQueryMode with an argument of true.

equalToQueryValues

public 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

public boolean fetch()

Attempts to fetch objects from the EODataSource, returning true on success and false on failure.

Before fetching, invokes endEditing and sends displayGroupShouldFetch to the delegate, returning false if either of these methods does. If both return true, sends a fetchObjects message to the receiver's EODataSource to replace the object array, and if successful sends the delegate a displayGroupDidFetchObjects message.

fetch

public void fetch(Object anObject)

(com.apple.client.eointerface only) This action method invokes fetch.

fetchesOnLoad

public boolean fetchesOnLoad()

Returns true if the receiver fetches automatically after being loaded from a nib file, false if it must be told explicitly to fetch. The default is false. You can set this behavior in Interface Builder using the Inspector panel.

See Also: fetch, setFetchesOnLoad

finishInitialization

public void finishInitialization()

(com.apple.client.eointerface only) Invoked from the EODisplayGroup constructor and from awakeFromNib to finish initializing a newly created display group. You should never invoke this method directly. Sets the receiver's editing context to it's data source's editing context (if available), registers the receiver for ObjectsChangedInEditingContextNotifications and InvalidatedAllObjectsInStoreNotifications, establishes the receiver as an editor for the editing context, and establishes the receiver as the editing context's message handler (unless the editing context already has a message handler).

greaterThanQueryValues

public 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.

inQueryMode

public boolean inQueryMode()

Returns true to indicate that the receiver is in query mode, false 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

public void insert(Object sender)

(com.apple.client.eointerface only) This action method invokes insertNewObjectAtIndex with an index just past the first index in the selection, or 0 if there's no selection.

insertedObjectDefaultValues

public 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.

insertNewObjectAtIndex

public Object insertNewObjectAtIndex(int anIndex)

(com.apple.yellow.eointerface only) Asks the receiver's EODataSource to create a new object by sending it a createObject message, then inserts the new object using insertObjectAtIndex. 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 displayGroupCreateObjectFailed message or, if the delegate doesn't respond, opens an attention panel to inform the user of the error.

See Also: insert

insertObjectAtIndex

public void insertObjectAtIndex( Object anObject, 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 displayGroupShouldInsertObject. If the delegate refuses, anObject isn't inserted. After successfully inserting the object, this method informs the delegate with a displayGroupDidInsertObject message, and selects the newly inserted object. Throws an exception if index is out of bounds.

Unlike the insertNewObjectAtIndex 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.

public Object insertNewObjectAtIndex(int anIndex)

(com.apple.client.eointerface only) Asks the receiver's EODataSource to create a new object by sending it a createObject message, then inserts the new object using insertObjectAtIndex. The EODataSource createObject method has the effect of inserting the object into the EOEditingContext.

lessThanQueryValues

public 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

public 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

public NSArray observingAssociations()

Returns all EOAssociations that observe the receiver's objects.

qualifier

public 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

public 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.

See Also: qualifyDisplayGroup, qualifyDataSource

qualifyDataSource

public 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.

public void qualifyDataSource(Object sender)

(com.apple.client.eointerface only) This action method simply invokes the no argument version.

qualifyDisplayGroup

public 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.

public void qualifyDisplayGroup(Object sender)

(com.apple.client.eointerface only) This action method simply invokes the no argument version.

queryBindingValues

public 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

public 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

public void redisplay()

Notifies all observing associations to redisplay their values.

See Also: observingAssociations

selectedObject

public Object selectedObject()

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

See Also: displayedObjects, selectionIndexes

selectedObjects

public NSArray selectedObjects()

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

See Also: displayedObjects, selectionIndexes

selectedObjectValueForKey

public Object selectedObjectValueForKey(String key)

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

See Also: valueForObjectAtIndex

selectionChanged

public boolean selectionChanged()

Returns true if the selection has changed and not all observers have been notified, false otherwise. EOAssociations use this in their subjectChanged methods to determine what they need to update.

See Also: contentsChanged

selectionIndexes

public NSArray selectionIndexes()

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

selectNext

public boolean selectNext()

Attempts to select the object just after the currently selected one, returning true if successful and false if not. The selection is altered in this way:

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

public void selectNext(Object sender)

(com.apple.client.eointerface only) This action method simply invokes the no argument version.

selectObject

public boolean selectObject(Object anObject)

Returns true to indicate that the receiver has found and selected anObject, false 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

public boolean selectObjectsIdenticalTo(NSArray objects)

Attempts to select the objects in the receiver's displayed objects array which are equal to those of objects, returning true if successful and false otherwise.

selectObjectsIdenticalToSelectFirstOnNoMatch

public boolean selectObjectsIdenticalTo( NSArray objects, boolean flag)

(com.apple.client.eointerface only) Selects the objects in the receiver's displayed objects array that are equal to those of objects, returning true if successful and false otherwise. If no objects in the displayed objects array match objects and flag is true, attempts to select the first object in the displayed objects array.

See Also: setSelectionIndexes

selectPrevious

public boolean selectPrevious()

Attempts to select the object just before the presently selected one, returning true if successful and false if not. The selection is altered in this way:

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

public void selectPrevious(Object anObject)

(com.apple.client.eointerface only) This action method simply invokes the no argument version.

selectsFirstObjectAfterFetch

public boolean selectsFirstObjectAfterFetch()

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

setDataSource

public 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 ObjectsChangedInEditingContextNotification and InvalidatedAllObjectsInStoreNotification 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

public void setDefaultStringMatchFormat(String format)

Sets how pattern matching will be performed on String values in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues). This format is used for query dictionary properties that have String 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

public void setDefaultStringMatchOperator(String matchOperator)

Sets the operator used to perform pattern matching for String values in the queryMatch dictionary. This operator is used for properties listed in the query dictionaries ( equalToQueryValues, greaterThanQueryValues, and lessThanQueryValues) that have String 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

public void setDelegate(Object anObject)

Sets the receiver's delegate to anObject.

See Also: delegate

setEqualToQueryValues

public 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

public void setFetchesOnLoad(boolean flag)

Controls whether the receiver automatically fetches its objects after being loaded from a nib file. If flag is true it does; if flag is false the receiver must be told explicitly to fetch. The default is false. You can also set this behavior in Interface Builder using the Inspector panel.

See Also: fetch, fetchesOnLoad

setGreaterThanQueryValues

public 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

public void setInQueryMode(boolean flag)

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

See Also: inQueryMode, enterQueryMode

setInsertedObjectDefaultValues

public 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.

See Also: insertedObjectDefaultValues

setLessThanQueryValues

public 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

public 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

public 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

public 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.

Note: To set the qualifier used to fetch objects from the database, set the qualifier of the display group's dataSource (assuming that the data source is an EODatabaseDataSource).

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

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

setQueryBindingValues

public 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

public 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.

setSelectedObject

public void setSelectedObject(Object anObject)

Sets the selected objects to anObject.

setSelectedObjects

public void setSelectedObjects(NSArray objects)

Sets the selected objects to objects.

setSelectedObjectValue

public boolean setSelectedObjectValue( Object value, String key)

Invokes setValueForObject with the first selected object, returning true if successful and false otherwise. This method should be invoked only by EOAssociation objects to propagate changes from display objects.

setSelectionIndexes

public boolean setSelectionIndexes(NSArray indexes)

Selects the objects at indexes in the receiver's array if possible, returning true if successful and false if not (in which case the selection remains unaltered). indexes is an array of Numbers. 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 false, this method fails and returns false. This method then checks the delegate with a displayGroupShouldChangeSelection message. If the delegate returns false, this method also fails and returns false. If the receiver successfully changes the selection, its observers (typically EOAssociations) each receive a subjectChanged message.

setSelectsFirstObjectAfterFetch

public void setSelectsFirstObjectAfterFetch(boolean 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 true it does; if flag is false then no objects are selected. By default, display groups select the first object after a fetch when there was no previous selection.

setSortOrderings

public 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 displayGroupDisplayArrayForObjects, that method is used instead of the sort orderings to order the objects.

See Also: displayedObjects, sortOrderings

setUsesOptimisticRefresh

public void setUsesOptimisticRefresh(boolean flag)

Controls how the receiver redisplays on changes to objects. If flag is true it redisplays only when elements of its displayed objects array change; if flag is false 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 false. You can also change this setting in Interface Builder's Inspector panel using the Refresh All check box.

See Also: usesOptimisticRefresh

setValidatesChangesImmediately

public void setValidatesChangesImmediately(boolean 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 validateValueForKey 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 true, the receiver immediately presents an attention panel indicating the validation error. If this method is invoked with a flag of false, 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

setValueForObject

public boolean setValueForObject( Object value, Object anObject, String key)

Sets a property of anObject, identified by key, to value. Returns true if successful and false otherwise. If a new value is set, sends the delegate a displayGroupDidSetValueForObject 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 validateValueForKey message, returning false if the object refuses to validate value. Otherwise, validation errors are checked by the EOEditingContext when it attempts to save changes.

setValueForObjectAtIndex

public boolean setValueForObjectAtIndex( Object value, int index, String key)

Invokes setValueForObject with the object at index, returning true if successful and false otherwise. This method should be invoked only by EOAssociation objects to propagate changes from display objects.

sortOrderings

public 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

undoManager

public NSUndoManager undoManager()

(com.apple.client.eointerface only) Returns the receiver's undo manager.

updateDisplayedObjects

public void updateDisplayedObjects()

Recalculates the receiver's displayed objects array and redisplays. If the receiver's delegate responds to displayGroupDisplayArrayForObjects, 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

public 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 true. EOAssociations can use this method to optimize redisplay of their user interface objects.

usesOptimisticRefresh

public boolean usesOptimisticRefresh()

Returns true if the receiver redisplays only when its displayed objects change, false if it redisplays on any change in its EOEditingContext.

See Also: setUsesOptimisticRefresh

validatesChangesImmediately

public boolean validatesChangesImmediately()

Returns true if the receiver immediately handles validation errors, or false if it leaves errors for the EOEditingContext to handle when saving changes.

See Also: setValidatesChangesImmediately

Notifications

DisplayGroupWillFetchNotification

public static final String DisplayGroupWillFetchNotification

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

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