Visual C++ Extensions Header in Detail

Visual C++ Extensions Header in Detail

The following header, icrsint.h, details the interface that allow clients to retrieve fields from a Recordset into variables defined in a class derived from CADORecordBinding. You must specify an ADO binding macro for each field you intend to access.

#ifndef _ICRSINT_H_
#define _ICRSINT_H_

#include <olectl.h>
#include <stddef.h>

// forwards
class CADORecordBinding;

#define classoffset(base, derived) ((DWORD)(static_cast<base*>((derived*)8))-8)

enum ADOFieldStatusEnum
{    
    adFldOK = 0,
    adFldBadAccessor = 1,
    adFldCantConvertValue = 2,
    adFldNull = 3,
    adFldTruncated = 4,
    adFldSignMismatch = 5,
    adFldDataOverFlow = 6,
    adFldCantCreate = 7,
    adFldUnavailable = 8,
    adFldPermissionDenied = 9,
    adFldIntegrityViolation = 10,
    adFldSchemaViolation = 11,
    adFldBadStatus = 12,
    adFldDefault = 13
};

typedef struct stADO_BINDING_ENTRY
{
    ULONG      ulOrdinal;
    WORD       wDataType;
    BYTE       bPrecision;
    BYTE       bScale;
    ULONG      ulSize;
    ULONG      ulBufferOffset;
    ULONG      ulStatusOffset;
    ULONG      ulLengthOffset;
    ULONG      ulADORecordBindingOffSet;
    BOOL       fModify;
} ADO_BINDING_ENTRY;

#define BEGIN_ADO_BINDING(cls) public: \
    typedef cls ADORowClass; \
    const ADO_BINDING_ENTRY* STDMETHODCALLTYPE GetADOBindingEntries() { \
    static const ADO_BINDING_ENTRY rgADOBindingEntries[] = { 

//
// Fixed length non-numeric data
//
#define ADO_FIXED_LENGTH_ENTRY(Ordinal, DataType, Buffer, Status, Modify)\
    {Ordinal, \
    DataType, \
    0, \
    0, \
    0, \
    offsetof(ADORowClass, Buffer), \
    offsetof(ADORowClass, Status), \
    0, \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

#define ADO_FIXED_LENGTH_ENTRY2(Ordinal, DataType, Buffer, Modify)\
    {Ordinal, \
    DataType, \
    0, \
    0, \
    0, \
    offsetof(ADORowClass, Buffer), \
    0, \
    0, \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

//
// Numeric data
// 
#define ADO_NUMERIC_ENTRY(Ordinal, DataType, Buffer, Precision, Scale, Status, Modify)\
    {Ordinal, \
    DataType, \
    Precision, \
    Scale, \
    0, \
    offsetof(ADORowClass, Buffer), \
    offsetof(ADORowClass, Status), \
    0, \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

#define ADO_NUMERIC_ENTRY2(Ordinal, DataType, Buffer, Precision, Scale, Modify)\
    {Ordinal, \
    DataType, \
    Precision, \
    Scale, \
    0, \
    offsetof(ADORowClass, Buffer), \
    0, \
    0, \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

//
// Variable length data
//
#define ADO_VARIABLE_LENGTH_ENTRY(Ordinal, DataType, Buffer, Size, Status, Length, Modify)\
    {Ordinal, \
    DataType, \
    0, \
    0, \
    Size, \
    offsetof(ADORowClass, Buffer), \
    offsetof(ADORowClass, Status), \
    offsetof(ADORowClass, Length), \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

#define ADO_VARIABLE_LENGTH_ENTRY2(Ordinal, DataType, Buffer, Size, Status, Modify)\
    {Ordinal, \
    DataType, \
    0, \
    0, \
    Size, \
    offsetof(ADORowClass, Buffer), \
    offsetof(ADORowClass, Status), \
    0, \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

#define ADO_VARIABLE_LENGTH_ENTRY3(Ordinal, DataType, Buffer, Size, Length, Modify)\
    {Ordinal, \
    DataType, \
    0, \
    0, \
    Size, \
    offsetof(ADORowClass, Buffer), \
    0, \
    offsetof(ADORowClass, Length), \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

#define ADO_VARIABLE_LENGTH_ENTRY4(Ordinal, DataType, Buffer, Size, Modify)\
    {Ordinal, \
    DataType, \
    0, \
    0, \
    Size, \
    offsetof(ADORowClass, Buffer), \
    0, \
    0, \
    classoffset(CADORecordBinding, ADORowClass), \
    Modify},

#define END_ADO_BINDING()   {0, adEmpty, 0, 0, 0, 0, 0, 0, 0, FALSE}};\
    return rgADOBindingEntries;}

//
// Interface that the client 'record' class needs to support. The ADO Binding entries
// provide the implementation for this interface.
//
class CADORecordBinding
{
public:
    STDMETHOD_(const ADO_BINDING_ENTRY*, GetADOBindingEntries) (VOID) PURE;
};

//
// Interface that allows a client to fetch a record of data into class data members.
//
struct __declspec(uuid("00000544-0000-0010-8000-00aa006d2ea4")) IADORecordBinding;
DECLARE_INTERFACE_(IADORecordBinding, IUnknown)
{
public:
    STDMETHOD(BindToRecordset) (CADORecordBinding *pAdoRecordBinding) PURE;
    STDMETHOD(AddNew) (CADORecordBinding *pAdoRecordBinding) PURE;
    STDMETHOD(Update) (CADORecordBinding *pAdoRecordBinding) PURE;
};

#endif // !_ICRSINT_H_