EOAdaptorChannel.Delegate

(informal interface)

Package:
com.webobjects.eoaccess

Interface Description

EOAdaptorChannel sends messages to its delegate for nearly every operation that would affect data in the database server. The delegate can use these methods to preempt these operations, modify their results, or simply track activity.

Instance Methods

adaptorChannelDidChangeResultSet

public abstract void adaptorChannelDidChangeResultSet(Object channel)

Invoked from fetchRow when a select operation resulted in multiple result sets. This method tells the delegate that the next invocation of fetchRow will fetch from the next result set. This method is invoked when fetchRow returns null and there are still result sets left to fetch. The delegate can invoke setAttributesToFetch to prepare for fetching the new rows.

adaptorChannelDidEvaluateExpression

public abstract void adaptorChannelDidEvaluateExpression( Object channel, EOSQLExpression expression)

Invoked from evaluateExpression to tell the delegate that a query language expression has been evaluated by the database server.

adaptorChannelDidExecuteStoredProcedure

public abstract void adaptorChannelDidExecuteStoredProcedure( Object channel, EOStoredProcedure procedure, NSDictionary values)

Invoked from executeStoredProcedure after procedure is executed successfully.

adaptorChannelDidFetchRow

public abstract void adaptorChannelDidFetchRow( Object channel, NSMutableDictionary row)

Invoked from fetchRow after a row is fetched successfully. This method is not invoked if an exception occurs during the fetch or if the same returns null because there are no more rows in the current result set. The delegate may modify row, which will be returned from fetchRow.

adaptorChannelDidFinishFetching

public abstract void adaptorChannelDidFinishFetching(Object channel)

Invoked from fetchRow to tell the delegate that fetching is finished for the current select operation. This method is invoked when a fetch ends in fetchRow because there are no more result sets.

adaptorChannelDidPerformOperations

public abstract Throwable adaptorChannelDidPerformOperations( Object channel, NSArray operations, Throwable exception)

Invoked from performAdaptorOperations. exception is null if no exception was raised while operations were performed. Otherwise, exception is the raised exception. The delegate can return the same or a different exception, which is re-raised by performAdaptorOperations, or it can return null to prevent the adaptor channel from raising an exception.

adaptorChannelDidSelectAttributes

public abstract void adaptorChannelDidSelectAttributes( Object channel, NSArray attributes, com.webobjects.eocontrol.EOFetchSpecification fetchSpecification, boolean flag, EOEntity entity)

Invoked from selectAttributes to tell the delegate that rows have been selected in the database server.

adaptorChannelShouldConstructStoredProcedureReturnValues

public abstract NSDictionary adaptorChannelShouldConstructStoredProcedureReturnValues(Object channel)

Invoked from returnValuesForLastStoredProcedureInvocation to tell the delegate that channel is constructing return values for the last stored procedure evaluated. If the delegate returns a value other than null, that value will be returned immediately from returnValuesForLastStoredProcedureInvocation.

adaptorChannelShouldEvaluateExpression

public abstract boolean adaptorChannelShouldEvaluateExpression( Object channel, EOSQLExpression expression)

Invoked from evaluateExpression to tell the delegate that channel is sending an expression to the database server. The delegate returns true to permit the adaptor channel to send expression to the server. If the delegate returns false, the adaptor channel does not send the expression and returns immediately. When the delegate returns false, the adaptor channel expects that the implementor of the delegate has done the work that evaluateExpression would have done. The delegate can create a new EOSQLExpression and send the expression itself before returning false.

adaptorChannelShouldExecuteStoredProcedure

public abstract NSDictionary adaptorChannelShouldExecuteStoredProcedure( Object channel, EOStoredProcedure procedure, NSDictionary values)

Invoked from executeStoredProcedure to tell the delegate that channel is executing a stored procedure. If the delegate returns a value other than null, that value is used as the arguments to the stored procedure instead of values.

adaptorChannelShouldReturnValuesForStoredProcedure

public abstract NSDictionary adaptorChannelShouldReturnValuesForStoredProcedure( Object channel, NSDictionary returnValues)

Invoked from returnValuesForLastStoredProcedureInvocation to tell the delegate that channel is returning values for a stored procedure. If the delegate returns a value other than null, that value is returned from returnValuesForLastStoredProcedureInvocation instead of returnValues.

adaptorChannelShouldSelectAttributes

public abstract boolean adaptorChannelShouldSelectAttributes( Object channel, NSArray attributes, com.webobjects.eocontrol.EOFetchSpecification fetchSpecification, boolean flag, EOEntity entity)

Invoked from selectAttributes to ask the delegate whether a select operation should be performed. The delegate should not modify fetchSpecification. Instead, if the delegate wants to perform a different select it should invoke selectAttributes itself with a new fetch specification, and return false (indicating that the adaptor channel should not perform the select itself).

adaptorChannelWillFetchRow

public abstract void adaptorChannelWillFetchRow(Object channel)

Invoked from fetchRow to tell the delegate that a single row will be fetched. The delegate can determine the attributes used by the fetch by sending attributesToFetch to channel, and can change the set of attributes to fetch by sending setAttributesToFetch to channel. The adaptor channel performs the actual fetch.

adaptorChannelWillPerformOperations

public abstract NSArray adaptorChannelWillPerformOperations( Object channel, NSArray operations)

Invoked from performAdaptorOperations to tell the delegate that channel is performing the EOAdaptorOperations in operations. The delegate may return operations or a different NSArray for the adaptor channel to perform. If the delegate returns null, the adaptor channel does not perform the operations and returns from the method immediately.