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Annotation of Examples/DatabaseKit/Evaluator/MultiBinder.h, revision 1.1

1.1     ! root        1: 
        !             2: /*
        !             3: MultiBinder.h
        !             4: A Binder that knows about multiple result sets 
        !             5: 
        !             6: MultiBinders are used instead of DBBinders in order to retrieve
        !             7: non-rectangular return results from Sybase or other similar stored
        !             8: procedures.
        !             9: 
        !            10: MultiBinders only work in the mode where the binder itself creates
        !            11: the recordPrototype for the binder.  You cannot provide your own
        !            12: recordPrototypes for the MultiBinder.
        !            13: 
        !            14: If you know exactly the sequence of properties the stored procedure
        !            15: will be returning to you, then:
        !            16: 1.  Create a List for each [rectangular] result set the stored
        !            17:     procedure returns.  Each List should contain, in the order the
        !            18:     stored procedure will return them, the attributes returned from
        !            19:     the database model.  Note that the attributes need not, in
        !            20:     the case of the MultiBinder, be from the same entity.
        !            21: 2.  Place all these Lists, in the order in which those result
        !            22:     sets will be returned by the stored procedure, into a temporary
        !            23:     List.  Pass that temporary list as the argument to
        !            24:     [multiBinder initFromPropertyLists:].  After initializing the binder,
        !            25:     the temporary list may be freed.  The underlying lists created in
        !            26:     step #1 are now owned by the MultiBinder, and will be freed
        !            27:     when the MultiBinder is freed.
        !            28: 3.  Invoke the stored procedure via [multiBinder evaluateString:].
        !            29: 4.  Repeatedley call [multiBinder setNext].  You can then call 
        !            30:     [multiBinder valueForProperty:] for each property.  Use the 
        !            31:     delegate method binderDidChangeResultSet: to find out when you
        !            32:     cross result set boundaries.
        !            33: 5.  All result sets have been retrieved when [multiBinder setNext]
        !            34:     returns nil.  Note that you should have received as many calls
        !            35:     to binderDidChangeResultSet: as there were result sets returned
        !            36:     from your stored procedure.
        !            37: 
        !            38: If you want to simply receive whatever the stored procedure happens
        !            39: to return, either because of your programs' task or because the 
        !            40: stored procedure conditionally returns different things:
        !            41: 1.  Pass nil as the argument to [MultiBinder initFromPropertyLists:].
        !            42: 2.  Repeatedley call [multiBinder setNext].  You should interrogate
        !            43:     the binder via [multiBinder getCurrentProperies:] to get the
        !            44:     new list of properties whenever the delegate method
        !            45:     binderDidChangeResultSet: is called.  DO NOT call getProperties:.
        !            46: 3.  All rows of all result sets are retrieved when 
        !            47:     [multiBinder setNext] returns nil.
        !            48: 
        !            49: */
        !            50: 
        !            51: #import <dbkit/dbkit.h>
        !            52: 
        !            53: @interface MultiBinder:DBBinder
        !            54: {
        !            55:     unsigned int       currentResultSet; /*  index into the list of lists */
        !            56:     List               *propListList; /* a list of property lists for the result sets */
        !            57: }
        !            58: 
        !            59: - initFromPropertyLists:(List *)propLists; /*  copies subsidiary lists out of propLists */
        !            60: - (unsigned int)currentResultSet; /* returns the index of the current result set */
        !            61: - (List *)getCurrentProperties:(List *)aList; /* fills aList with the current properties */
        !            62: 
        !            63: @end
        !            64: 
        !            65: @interface Object (MultiBinderDelegateMethods)
        !            66: - binderWillChangeResultSet:binder; /* called before changing result sets */
        !            67: - binderDidChangeResultSet:binder; /* called before fetching from a new result set */
        !            68: @end
        !            69: 
        !            70: @interface DBBinder (MultiBinderMethods)
        !            71: - (List *)getCurrentProperties:(List *)aList;
        !            72: @end
        !            73: 

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