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EOAdaptorOperation

Inherits from: NSObject

Conforms to: NSObject
(NSObject)

Declared in: EOAccess/EODatabaseOperation.h

Class Description

An EOAdaptorOperation object represents a primitive operation in a database server-lock, insert, update, or delete a row; or execute a stored procedure-and all the necessary information required by the operation. An EOAdaptorOperation is processed by an EOAdaptorChannel object in the method performAdaptorOperation:. You don't ordinarily create instances of EOAdaptorOperation; rather, the Framework automatically creates an EOAdaptorOperation object and sends it to an adaptor channel when your application needs the database server to perform an operation. You generally interact with EOAdaptorOperation objects only if you need to specify the order in which a set of operations are carried out (see the description for the EODatabaseContext delegate method databaseContext:willOrderAdaptorOperationsFromDatabaseOperations:).

An EOAdaptorOperation has an entity and an operator (the type of operation the object represents). An adaptor operation's operator (EOAdaptorLockOperator, EOAdaptorInsertOperator, EOAdaptorUpdateOperator, EOAdaptorDeleteOperator, or EOAdaptorStoredProcedureOperator) determines additional, operator-dependent information used by the EOAdaptorOperation object. For example, only a stored procedure operation has an EOStoredProcedure object. The operator-dependent information is accessible using the methods described below.

Method Types

Creating a new EOAdaptorOperation

- initWithEntity:

Accessing the entity

- entity

Accessing the operator

- setAdaptorOperator:

- adaptorOperator

Accessing the qualifier

- setQualifier:

- qualifier

Accessing locking attributes

- setAttributes:

- attributes

Accessing operation values

- setChangedValues:

- changedValues

Accessing a stored procedure

- setStoredProcedure:

- storedProcedure

Handling errors during the operation

- setException:

- exception

Comparing operations

- compareAdaptorOperation:

Instance Methods

adaptorOperator

- (EOAdaptorOperator)adaptorOperator

Returns the receiver's adaptor operator. The operator indicates which of the other adaptor operation attributes are valid. For example, an adaptor operation whose operator is EOAdaptorInsertOperator uses changedValues, but not attributes, qualifier, or storedProcedure.

attributes

- (NSArray *)attributes

Returns the array of attributes to select when locking the row. If attributes have not been assigned to the receiver, the primary key attributes are selected. Only valid for adaptor operations with the EOAdaptorLockOperator.

changedValues

- (NSDictionary *)changedValues

Returns the dictionary of values that need to be updated, inserted, or compared for locking purposes.

compareAdaptorOperation:

- (NSComparisonResult)compareAdaptorOperation:(EOAdaptorOperation *)operation

Orders adaptor operations alphabetically by entity name and by adaptor operator within the same entity. The adaptor operators are ordered as follows:

EOAdaptorLockOperator
EOAdaptorInsertOperator
EOAdaptorUpdateOperator
EOAdaptorDeleteOperator
EOAdaptorStoredProcedureOperator

EOAdaptorLockOperator precedes EOAdaptorInsertOperator, EOAdaptorInsertOperator precedes EOAdaptorUpdateOperator, and so on.

An EODatabaseContext uses compareAdaptorOperation: to order adaptor operations before invoking EOAdaptorChannel's performAdaptorOperations: method.

entity

- (EOEntity *)entity

Returns the entity to which the operation will be applied.

See Also: - initWithEntity:

exception

- (NSException *)exception

Returns the exception that was raised when an adaptor channel attempted to process the receiver. Returns nil if no exception was raised or if the receiver hasn't been processed yet.

qualifier

- (EOQualifier *)qualifier

Returns the qualifier that identifies the specific row to which the operation applies. Not valid with adaptor operations with the operators EOAdaptorInsertOperator and EOAdaptorStoredProcedureOperator.

initWithEntity:

- initWithEntity:(EOEntity *)entity

The designated initializer, initializes a new EOAdaptorOperation instance, and sets the entity to which the operation will be applied. Returns self.

See Also: - entity

setAdaptorOperator:

- (void)setAdaptorOperator:(EOAdaptorOperator)adaptorOperator

Sets the receiver's operator to adaptorOperator, which is one of the following:

EOAdaptorLockOperator
EOAdaptorInsertOperator
EOAdaptorUpdateOperator
EOAdaptorDeleteOperator
EOAdaptorStoredProcedureOperator

For more information, see the discussion on adaptor operators in the class description above.

setAttributes:

- (void)setAttributes:(NSArray *)attributes

Sets the array of attributes to select when locking the row. The selected values are compared in memory to the corresponding snapshot values to determine if a row has changed since the application last fetched it. attributes is an array of EOAttribute objects that can't be compared in a qualifier (generally BLOB types); it should not be nil or empty. Generally, an adaptor operation's qualifier contains all the comparisons needed to verify that a row hasn't changed since the application last fetched, inserted, or updated it. In this case (if there aren't any attributes that can't be compared in a qualifier), attributes should contain primary key attributes. This method is only valid for adaptor operations with the EOAdaptorLockOperator.

setChangedValues:

- (void)setChangedValues:(NSDictionary *)changedValues

Sets the dictionary of values that need to be updated, inserted, or compared for locking purposes. changedValues is a dictionary object whose keys are attribute names and whose values are the values for those attributes. As summarized in the following table, the contents of changedValues depends on the receiver's operator:

Operator	Contents of changedValues Dictionary
`EOAdaptorLockOperator`	Snapshot values used to verify that the database row hasn't changed since this application last fetched it
`EOAdaptorInsertOperator`	The values to insert
`EOAdaptorUpdateOperator`	The new values for the columns to update
`EOAdaptorDeleteOperator`	Snapshot values (changedValues is only valid for `EOAdaptorDeleteOperator` if the receiver's entity uses a stored procedure to perform delete operations.)
`EOAdaptorStoredProcedureOperator`	Snapshot values

setException:

- (void)setException:(NSException *)exception

Sets the receiver's exception to exception. This method is typically invoked from EOAdaptorChannel's performAdaptorOperations: method. If a database error occurs while processing an adaptor operation, the adaptor channel creates an exception and assigns it to the adaptor operation.