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Documentation > WebObjects 4.5 >
EOAdaptor Reference
(informal interface)
Package:
com.apple.yellow.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
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.
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.
public abstract void adaptorChannelDidExecuteStoredProcedure(
Object channel,
EOStoredProcedure procedure,
NSDictionary values)
Invoked from executeStoredProcedure after procedure is
executed successfully.
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.
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.
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.
public abstract void adaptorChannelDidSelectAttributes(
Object channel,
NSArray attributes,
com.apple.yellow.eocontrol.EOFetchSpecification fetchSpecification,
boolean flag,
EOEntity entity)
Invoked from selectAttributes to
tell the delegate that rows have been selected in the database server.
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.
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.
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.
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.
public abstract boolean adaptorChannelShouldSelectAttributes(
Object channel,
NSArray attributes,
com.apple.yellow.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).
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.
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.