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Documentation > WebObjects 4.5 >
EOAdaptor Reference
Inherits
from: com.apple.yellow.eocontrol.EODataSource : NSObject
Package: com.apple.yellow.eoaccess
Class Description
EODatabaseDataSource is a concrete subclass of EODataSource
(defined in EOControl) that fetches objects based on an EOModel,
using an EODatabaseContext that services the data source's EOEditingContext
(defined in EOControl). An EODatabaseDataSource can be set up to
fetch all objects for its root entity, to fetch objects matching
a particular EOFetchSpecification, and to further filter its fetching
with an auxiliary qualifier.
EODatabaseDataSource implements all the functionality defined
by EODataSource: In addition to fetching objects, it can insert
and delete them (provided the entity isn't read-only). See the EODataSource
class specification for more information on these topics.
As with other data sources, EODatabaseDataSource can also
provide a detail data source. The most significant consequence of
using an master-detail configuration is that the detail operates
directly on the master's object graph. The EODetailDataSource
has a master object and a detail key through which
the detail data source accesses the its objects. The master object
is simply the object that's selected in the master display group,
and the detail key is the name of a relationship property in the
master object. When the detail display group asks its data source
to fetch, the EODetailDataSource simply gets the value for the relationship
property identified by the detail key from its master object and
returns it. When you add and remove objects from the detail, you're
directly modifying the master's relationship array. In fact, you
can think of EODetailDataSource as an interface to its master object's
relationship property.
Method Types
- Constructors
- EODatabaseDataSource
- Accessing selection criteria
- auxiliaryQualifier
- fetchSpecification
- fetchSpecificationForFetch
- fetchSpecificationName
- setAuxiliaryQualifier
- setFetchSpecification
- setFetchSpecificationByName
- Accessing objects used
for fetching
- entity
- databaseContext
- Enabling fetching
- setFetchEnabled
- isFetchEnabled
- Accessing qualifier bindings
- qualifierBindingKeys
- qualifierBindings
- setQualifierBindings
- Other
- deleteObject
- insertObject
- dataSourceQualifiedByKey
- qualifyWithRelationshipKey
Constructors
public EODatabaseDataSource(
com.apple.yellow.eocontrol.EOEditingContext anEditingContext,
String anEntityName)
Creates and returns a new EODatabaseDataSource
object. The new EODatabaseDataSource fetches objects into anEditingContext for
the EOEntity named by anEntityName.
If anEditingContext's EOObjectStoreCoordinator (EOControl) doesn't
have an EODatabaseContext to service the model containing the named
entity, one is created. The new data source uses a fetch specification
that fetches all the entity's objects.
public EODatabaseDataSource(
com.apple.yellow.eocontrol.EOEditingContext anEditingContext,
String anEntityName,
String fetchSpecificationName)
Creates and returns a new EODatabaseDataSource
object. The new EODatabaseDataSource fetches objects into anEditingContext for
the EOEntity named by anEntityName.
If anEditingContext's EOObjectStoreCoordinator (EOControl) doesn't
have an EODatabaseContext to service the model containing the named
entity, one is created. The fetchSpecificationName argument
is used to find the named fetch specification in the entity. If
the fetchSpecificationName is not
included or is null, a new fetch specification
that fetches all the entity's objects is created.
Instance Methods
public com.apple.yellow.eocontrol.EOQualifier auxiliaryQualifier()
Returns the EOQualifier used to further filter
the objects fetched by the receiver's EOFetchSpecification (in
EOControl). See Also: fetchSpecificationForFetch, fetchSpecification
public EODatabaseContext databaseContext()
Returns the EODatabaseContext that the receiver
uses to access the external database. This is either the root EOObjectStore
for the receiver's EOEditingContext, or if the root is an EOCooperatingObjectStore, it's
the EODatabaseContext under that EOCooperatingObjectStore that services
the EOModel containing the EOEntity for the receiver. (EOObjectStore,
EOEditingContext, and EOCooperatingObjectStore are all defined in
EOControl.)
public com.apple.yellow.eocontrol.EODataSource dataSourceQualifiedByKey(String key)
Returns a detail data source that provides the
destination objects of the relationship named by key.
The returned detail data source can be qualified by using qualifierWithKey to
set a specific master object or to change the relationship key.
public void deleteObject(Object anObject)
Deletes anObject from
the data source. This method raises an exception on failure. If
the receiver registers undos for the deletion, the receiver may
receive a possibly redundant insertObject call.
public EOEntity entity()
Returns the EOEntity from which the receiver
fetches objects.
public com.apple.yellow.eocontrol.EOFetchSpecification fetchSpecification()
Returns the receiver's basic EOFetchSpecification.
Its EOQualifier is conjoined with the receiver's auxiliary EOQualifier
when the receiver fetches objects. The sender of this message can
alter the EOFetchSpecification directly, or replace it using setFetchSpecification.See
Also: fetchSpecificationForFetch, auxiliaryQualifier
public com.apple.yellow.eocontrol.EOFetchSpecification fetchSpecificationForFetch()
Returns a copy of the EOFetchSpecification that
the receiver uses to fetch. This is constructed by conjoining the
EOQualifier of the receiver's EOFetchSpecification with its auxiliary
EOQualifier. Modifying the returned EOFetchSpecification doesn't
affect the receiver's fetching behavior; use setFetchSpecification and setAuxiliaryQualifier for that purpose.See
Also: fetchSpecification, auxiliaryQualifier
public String fetchSpecificationName()
Returns the name of the fetch specification
(or null if there is no name).See Also: setFetchSpecificationByName
public void insertObject(Object anObject)
Inserts anObject into
the data source.
public boolean isFetchEnabled()
Returns true if the receiver's fetchObjects method
actually fetches objects, false if it returns an empty array without
fetching. Fetching is typically disabled in a master-peer configuration
when no object is selected in the master.See
Also: setFetchEnabled
public NSArray qualifierBindingKeys()
Returns an array of strings which is a union
of the binding keys from the fetch specification's qualifier and
the data source's auxiliary qualifier.See
Also: setQualifierBindings
public NSDictionary qualifierBindings()
Returns a set of bindings that will be used
for variable replacement on the fetch specification's qualifier and
the auxiliary qualifier before the fetch is executed.
public void qualifyWithRelationshipKey(
String key,
Object sourceObject)
Displays destination objects for the relationship
named key belonging to sourceObject. key should
be the same as the key specified in the dataSourceQualifiedByKey message
that created the receiver. If sourceObject is null,
the receiver qualifies itself to provide no objects.
public void setAuxiliaryQualifier(com.apple.yellow.eocontrol.EOQualifier aQualifier)
Sets the receiver's auxiliary qualifier to aQualifier.
The auxiliary qualifier usually adds conditions to the primary qualifier
and is useful for narrowing the scope of a data source without altering
its primary qualifier. This is especially useful for setting a qualifier
on a qualified peer data source, since a peer's primary qualifiers
specifies the matching criteria for the relationship it fetches
for. For more information on auxiliary qualifiers, see "Creating
a Master-Peer Configuration" in the "WebObjects Programming
Topics." See Also: fetchSpecificationForFetch, fetchSpecification
public void setFetchEnabled(boolean flag)
Controls whether the receiver can fetch. If flag is true the
receiver's fetchObjects method actually fetches
objects, if false it returns an empty array without fetching. Fetching
is typically disabled in a master-peer configuration when no object
is selected in the master. For example, EODatabaseDataSource's
implementation of qualifyWithRelationshipKey invokes
this method to enable or disable fetching based on whether a master
object is provided.See Also: isFetchEnabled
public void setFetchSpecification(com.apple.yellow.eocontrol.EOFetchSpecification fetchSpec)
Sets the receiver's basic EOFetchSpecification
to fetchSpec. Its EOQualifier is
conjoined with the receiver's auxiliary EOQualifier when the receiver
fetches objects. This method also sets the name of the fetch specification
to null.See Also: setAuxiliaryQualifier, fetchSpecificationForFetch, setFetchSpecificationByName
public void setFetchSpecificationByName(String fetchSpecificationName)
Sets the fetchSpecificationName as
given, and sets the fetch specification (used when supplying objects)
to the named fetch specification of the entity that was used to
initialize the data source. This method is an alternative to setFetchSpecification.See
Also: fetchSpecification, fetchSpecificationName
public void setQualifierBindings(NSDictionary bindings)
Sets a set of bindings that will be used for
variable replacement on the fetch specification's qualifier and the
auxiliary qualifier before the fetch is executed.See
Also: qualifierBindingKeys