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EOAdaptorOperation


Inherits from:
Object
Package:
com.webobjects.eoaccess

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 (AdaptorLockOperator, AdaptorInsertOperator, AdaptorUpdateOperator, AdaptorDeleteOperator, or AdaptorStoredProcedureOperator) 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

Constructors
EOAdaptorOperation
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


Constructors


EOAdaptorOperation

public EOAdaptorOperation(EOEntity entity)

Creates and returns a new EOAdaptorOperation, with entity as the entity to which the operation will be applied.

See Also: entity



Instance Methods


adaptorOperator

public int 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 AdaptorInsertOperator uses changedValues, but not attributes, qualifier, or storedProcedure.

attributes

public 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 AdaptorLockOperator.

changedValues

public NSDictionary changedValues()

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

compareAdaptorOperation

public int 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:

AdaptorLockOperator precedes AdaptorInsertOperator, AdaptorInsertOperator precedes AdaptorUpdateOperator, and so on.

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


entity

public EOEntity entity()

Returns the entity to which the operation will be applied.

exception

public Throwable exception()

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

qualifier

public com.webobjects.eocontrol.EOQualifier qualifier()

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

setAdaptorOperator

public void setAdaptorOperator(int adaptorOperator)

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

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


setAttributes

public 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 null 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 AdaptorLockOperator.

setChangedValues

public 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
AdaptorLockOperator Snapshot values used to verify that the database row hasn't changed since this application last fetched it
AdaptorInsertOperator The values to insert
AdaptorUpdateOperator The new values for the columns to update
AdaptorDeleteOperator Snapshot values (changedValues is only valid for AdaptorDeleteOperator if the receiver's entity uses a stored procedure to perform delete operations.)
AdaptorStoredProcedureOperator Snapshot values


setException

public void setException(Throwable 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.

setQualifier

public void setQualifier(com.webobjects.eocontrol.EOQualifier qualifier)

Sets the qualifier that identifies the row to which the adaptor operation is to be applied to qualifier.

setStoredProcedure

public void setStoredProcedure(EOStoredProcedure storedProcedure)

Sets the receiver's stored procedure to storedProcedure.

storedProcedure

public EOStoredProcedure storedProcedure()

Returns the receiver's stored procedure. Only valid with adaptor operations with the AdaptorStoredProcedureOperator.

toString

public String toString()

Description forthcoming.

© 2001 Apple Computer, Inc. (Last Published April 13, 2001)


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