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Documentation > WebObjects 4.5 >
EOAccess Reference
Inherits
from: NSObject
Conforms to: NSObject
(NSObject)
Declared in: EOAccess/EOModelGroup.h
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:
[[self 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 protocol. For more information on EOModelGroup
class delegate and instance delegate methods, see the EOModelGroup Class Delegate and EOModelGroup Delegate protocol 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
In EOModelGroup.h, EOModelGroupEOAccess defines NSString
constants for the names of the notifications it posts. For more
information on these notifications, see "Notifications" .
Method Types
- Accessing models
- - addModelWithFile:
- - modelNamed:
- - modelNames
- - models
- - modelWithPath:
- - removeModel:
- Accessing model groups
- + defaultGroup
- + setDefaultGroup:
- + globalModelGroup
- Searching a group
- - entityNamed:
- - entityForObject:
- - entitiesWithSharedObjects
- - fetchSpecificationNamed:entityNamed:
- - storedProcedureNamed:
- Loading all of a group's
objects
- - loadAllModelObjects
- Assigning a delegate
- + classDelegate
- - delegate
- + setClassDelegate:
- - setClassDelegate:
Class Methods
+ (id)classDelegate
Returns the EOModelGroup's class delegate.
This delegate optionally implements the defaultModelGroup method
(see the EOModelGroup Class Delegate protocol specification
for more information).See Also: + setClassDelegate:
+ (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
-nil
value,
this method is equivalent to globalModelGroup.See
Also: + classDelegate
+ (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
+ (void)setClassDelegate:(id)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 Class Delegate protocol specification
for more information).See Also: + classDelegate, - defaultModelGroup
+ (void)setDefaultGroup:(EOModelGroup
*)group
Sets the default model group to group.
If you've implemented the defaultModelGroup class
delegate method to return a non
-nil
value,
the delegate's return value overrides group as
the default model group.See Also: + defaultGroup, + setClassDelegate:
Instance Methods
- (void)addModel:(EOModel
*)model
Adds a model to
the receiver, sets the model's
model group to the receiver, and posts EOModelAddedNotification. Raises an
exception if the receiver already contains an EOModel with the same
name as the specified model.
- (EOModel *)addModelWithFile:(NSString
*)path
Creates an EOModel object with the contents
of the file identified by path, adds
the newly-created model to the receiver, and returns it. Throws
an exception if for any reason it cannot create the model from the
file specified by path. Uses the
EOModel method initWithContentsOfFile: to initialize
the new model, and adds it to the receiver.
- (id)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 protocol specification
for more information.See Also: - setClassDelegate:, + classDelegate
- (NSArray *)entitiesWithSharedObjects
Returns an array of entities that have objects
to load into a shared editing context.
- (EOEntity *)entityForObject:(id)object
Returns the EOEntity associated with object from
any of the models in the receiver that handle object, or nil if
none of the entities in the receiver handles object.See
Also: - entityForObject: (EOModel)
- (EOEntity *)entityNamed:(NSString
*)entityName
Searches each of the EOModels in the receiver
for the entity specified by entityName,
and returns the entity if found. Returns nil if it is unable to
find the specified entity.See Also: - entityNamed: (EOModel)
- (EOFetchSpecification *)fetchSpecificationNamed:(NSString
*)fetchSpecName
entityNamed:(NSString *)entityName
Returns the named fetch specification from the
entity specified by entityName in
the receiving model group.
- (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)
- (EOModel *)modelNamed:(NSString
*)modelName
Returns the EOModel named modelName if
it's part of the receiver, or nil if the receiver doesn't contain an
EOModel with the specified name.
- (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.
- (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.
- (EOModel *)modelWithPath:(NSString
*)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 nil. NSString's isEqual: method
is used to compare the paths, and each path is standardized (with stringByStandardizingPath) before comparison.See
Also: - path (EOModel)
- (void)removeModel:(EOModel
*)aModel
Removes aModel from
the receiver, and unbinds any connections to aModel from
other EOModels in the receiver. Posts EOModelInvalidatedNotification to the
default notification center after removing aModel from
the receiver.See Also: - EOModelGroup, - models
- (void)setDelegate:(id)anObject
Sets the receiver's delegate to anObject.
See the EOModelGroup Delegate protocol specification
for more information.See Also: - delegate
- (EOStoredProcedure *)storedProcedureNamed:(NSString
*)aName
Returns the stored procedure in the receiving
model group having the given name.
Notifications
EOModelGroup declares and posts the following notifications.
EOModelAddedNotification
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 |
EOModelInvalidatedNotification
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 |