PATH Documentation > WebObjects 4.5 > EOAdaptor Reference

EOModelGroup

Inherits from: NSObject

Package: com.apple.yellow.eoaccess

Class Description

An EOModelGroup represents an aggregation of related models (see the EOModel class specification for more information on models). When a model in the group needs to resolve a relationship to an entity in another model, it looks for that model in its group. Model groups allow applications to load entities and their properties only as they're needed, by distributing them among separate EOModels.

The default model group contains all models for an application, as well as any frameworks the application references. It is automatically created on demand. The entity name space among all of these models is global; consequently, the same entity name shouldn't appear in any two of the models. All cross-model information is represented in the models by entity name only. Binding the entity name to an actual entity is done at run-time within the EOModelGroup.

In the majority of applications, the automatic creation of the default model group is sufficient. However, your code can override this automatic creation; see "Setting Up A Model Group Programmatically" .

Accessing Models Within a Model Group

Each model lives within a group and can form connections to other models in its group. A model can find a related model using the statement:

this.modelGroup().modelNamed(name);

A data source can locate a model using the statement:

EOModelGroup.defaultGroup().modelNamed(name);

EOModeler puts models with identical names in separate groups to allow you to load two models with the same name at the same time.

EOModelGroup Delegates

Your EOModelGroup object should have a delegate which can influence how it finds and loads models. In addition to the delegates you assign to EOModelGroup instances, the EOModelGroup class itself can have a delegate. The class delegate implements a single method- defaultModelGroup-while the instance delegate can implement the methods defined in the EOModelGroup.Delegate interface. For more information on EOModelGroup class delegate and instance delegate methods, see the EOModelGroup.ClassDelegate and EOModelGroup.Delegate interface specifications, respectively. Note that the following delegate methods are set on EOModelGroup, rather than EOEntity, to provide a single point in the code where you can alter the database-to-objects mapping:

Constants

EOModelGroup defines String constants for the names of the notifications it posts. For more information on these notifications, see "Notifications" .

Method Types

Accessing models

addModelWithPath

modelNamed

modelNames

models

modelWithPath

removeModel

Accessing model groups

defaultGroup

setDefaultGroup

globalModelGroup

modelGroupForObjectStoreCoordinator

setModelGroup

Searching a group

entityNamed

entityForObject

entitiesWithSharedObjects

fetchSpecificationNamed

storedProcedureNamed

Loading all of a group's objects

loadAllModelObjects

Assigning a delegate

classDelegate

delegate

setClassDelegate

setClassDelegate

Static Methods

classDelegate

public static Object classDelegate()

Returns the EOModelGroup's class delegate. This delegate optionally implements the defaultModelGroup method (see the EOModelGroup.ClassDelegate interface specification for more information).

See Also: setClassDelegate

defaultGroup

public static EOModelGroup defaultGroup()

Returns the default EOModelGroup. Unless you've either specified a default model group with setDefaultGroup or implemented the defaultModelGroup class delegate method to return a non-null value, this method is equivalent to globalModelGroup.

See Also: classDelegate

globalModelGroup

public static EOModelGroup globalModelGroup()

Returns an EOModelGroup composed of all models in the resource directory of the main bundle, as well as those in all the bundles and frameworks loaded into the application.

See Also: defaultGroup

modelGroupForObjectStoreCoordinator

public static EOModelGroup modelGroupForObjectStoreCoordinator(com.apple.yellow.eocontrol.EOObjectStoreCoordinator anObjectStoreCoordinator)

Returns the EOModelGroup used by anObjectStoreCoordinator.

See Also: setModelGroup

setClassDelegate

public static void setClassDelegate(Object anObject)

Assigns anObject as the EOModelGroup's class delegate. The class delegate is optional; it allows you to determine the default model group (see the EOModelGroup.ClassDelegate interface specification for more information).

See Also: classDelegate, defaultModelGroup

setDefaultGroup

public static void setDefaultGroup(EOModelGroup group)

Sets the default model group to group. If you've implemented the defaultModelGroup class delegate method to return a non-null value, the delegate's return value overrides group as the default model group.

See Also: defaultGroup, setClassDelegate

setModelGroup

public static void setModelGroup( EOModelGroup group, com.apple.yellow.eocontrol.EOObjectStoreCoordinator anObjectStoreCoordinator)

Assigns group to anObjectStoreCoordinator. By default, an EOObjectStoreCoordinator uses the defaultGroup. You might want to assign a different group to an EOObjectStoreCoordinator if you need to scope models to particular coordinators-if different models have the same name, or if different entities in different models have the same name.

Instance Methods

addModel

public void addModel(EOModel model)

Adds a model to the receiver, sets the model's model group to the receiver, and posts ModelAddedNotification. Throws an exception if the receiver already contains an EOModel with the same name as the specified model.

addModelWithPath

public EOModel addModelWithPath(String path)

Creates an EOModel object with the contents of the file identified by path, and adds the newly created model to the receiver. Adds the new model to the receiver. Throws an exception if for any reason it cannot create the model from the file specified by path.

delegate

public Object delegate()

Returns the receiver's delegate, which is different from the EOModelGroup's class delegate. Each EOModelGroup object can have it's own delegate in addition to the delegate that's assigned to the EOModelGroup class. See the EOModelGroup.Delegate interface specification for more information.

See Also: setClassDelegate, classDelegate

entitiesWithSharedObjects

public NSArray entitiesWithSharedObjects()

Returns an array of entities that have objects to load into a shared editing context.

entityForObject

public EOEntity entityForObject(Object object)

Returns the EOEntity associated with object from any of the models in the receiver that handle object, or null if none of the entities in the receiver handles object.

See Also: entityForObject (EOModel)

entityNamed

public EOEntity entityNamed(String entityName)

Searches each of the EOModels in the receiver for the entity specified by entityName, and returns the entity if found. Returns null if it is unable to find the specified entity.

See Also: entityNamed (EOModel)

fetchSpecificationNamed

public com.apple.yellow.eocontrol.EOFetchSpecification fetchSpecificationNamed( String fetchSpecName, String entityName)

Returns the named fetch specification from the entity specified by entityName in the receiving model group.

loadAllModelObjects

public void loadAllModelObjects()

Sends loadAllModelObjects to each of the receiver's EOModels, thereby loading any EOEntities, EOAttributes, EORelationships, and EOStoredProcedures that haven't yet been loaded from each of the EOModels in the receiver.

See Also: loadAllModelObjects (EOModel)

modelNamed

public EOModel modelNamed(String modelName)

Returns the EOModel named modelName if it's part of the receiver, or null if the receiver doesn't contain an EOModel with the specified name.

modelNames

public NSArray modelNames()

Returns an array containing the names of all of the EOModels in the receiver, or an empty array if the receiver contains no EOModels. The order of the model names in the array isn't defined.

models

public NSArray models()

Returns an array containing the receiver's EOModels, or an empty array if the receiver contains no EOModels. The order of the models in the array isn't defined.

modelWithPath

public EOModel modelWithPath(String path)

If the receiver contains an EOModel whose path (as determined by sending path to the EOModel object) is equal to path, that EOModel is returned. Otherwise, returns null. String's equals method is used to compare the paths, and each path is standardized before comparison.

See Also: path (EOModel)

removeModel

public void removeModel(EOModel aModel)

Removes aModel from the receiver, and unbinds any connections to aModel from other EOModels in the receiver. Posts ModelInvalidatedNotification to the default notification center after removing aModel from the receiver.

See Also: EOModelGroup, models

setDelegate

public void setDelegate(Object anObject)

Sets the receiver's delegate to anObject. See the EOModelGroup.Delegate interface specification for more information.

See Also: delegate

storedProcedureNamed

public EOStoredProcedure storedProcedureNamed(String aName)

Returns the stored procedure in the receiving model group having the given name.

Notifications

EOModelGroup declares and posts the following notifications.

ModelAddedNotification

Posted by an EOModelGroup when an EOModel is added to the group. This notification is sent, for instance, inside Interface Builder when the user has saved changes to a model in EOModeler and the objects in Interface Builder must be brought back in sync. The old model is flushed and receivers of the notification (like data sources) can invoke modelNamed to re-fetch their models.

Notification Object	The newly added model.
Userinfo	None

ModelInvalidatedNotification

Posted by an EOModelGroup when an EOModel is removed from the group. This notification is sent, for instance, inside Interface Builder when the user has saved changes to a model in EOModeler and the objects in Interface Builder must be brought back in sync. The old model is flushed and receivers of the notification (like data sources) can invoke modelNamed to re-fetch their models.

Notification Object	The invalidated model.
Userinfo	None