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CALLBACK.C
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1997-05-06
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// BDE32 3.x - (C) Copyright 1996 by Borland International
// Callback.C
#include "snipit.h"
static const DBIPATH szTblName = "contacts";
static const DBIPATH szRstrctTblName= "TempRest";
static const char szTblType[] = szPARADOX;
pCHAR CallBackData;
#define NUMOFFIELDS 3
static DBIResult getFieldDescs(hDBICur hCur, UINT16 *uNumFields,
FLDDesc **fldDesc);
static DBIResult changeFieldDescs(UINT16 *uNumFields, FLDDesc *fldDescSrc,
FLDDesc *fldDescDest, CROpType *ecrFldOp);
CBRType DBIFN _export CallBackFunc(CBType ecbType, UINT32 iClientData,
pVOID pCbInfo);
//=====================================================================
// Function:
// TBRestructureCallBack();
//
// Description:
// This example shows how to register and use a callback for a table
// restructure. The restructure will simply drop fields.
//
// The following steps are followed:
// Getting the existing field descriptors
// Modifying the field descriptors to the new table structure
// Initializing the CRTblDesc (create table descriptor)
// Registering the callback
// Restructuring the table
// Unregistering the callback
//=====================================================================
void
TBRestructureCallBack (void)
{
hDBIDb hDb; // Handle to the database
hDBICur hCur; // Handle to the table
CRTblDesc crTblDesc; // Table descriptor
UINT16 uNumFields; // Number of fields
UINT16 uNumOfRecs = 5; // No. of records to display
FLDDesc *fldDescSrc; // Array of field descriptors
FLDDesc fldDescDest[NUMOFFIELDS]; // Restructure field descriptors
CROpType ecrFldOp[NUMOFFIELDS]; // Restructure operations
RESTCbDesc CbInfo; // Variable which is used within
// the callback
DBIResult rslt; // Return value from IDAPI
// functions
DBIPATH szKeyViol = "KEYVIOL"; // Name for the key violation table
Screen("*** Restructure CallBack Example ***\r\n");
BREAK_IN_DEBUGGER();
Screen(" Initializing IDAPI...");
if (InitAndConnect(&hDb) != DBIERR_NONE)
{
Screen("*** End of Example ***");
return;
}
Screen(" Setting the database directory... ");
rslt = DbiSetDirectory(hDb, (pCHAR) szTblDirectory);
ChkRslt(rslt, "SetDirectory");
Screen(" Open the %s table....", szTblName);
rslt = DbiOpenTable(hDb, (pCHAR) szTblName, (pCHAR) szTblType,
NULL, NULL, 0, dbiREADWRITE, dbiOPENSHARED,
xltFIELD, FALSE, NULL, &hCur);
if (ChkRslt(rslt, "OpenTable") != DBIERR_NONE)
{
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
return;
}
rslt = DbiSetToBegin(hCur);
ChkRslt(rslt, "SetToBegin");
Screen(" Display the %s table...", szTblName);
DisplayTable(hCur, uNumOfRecs);
// Get the field descriptors for the existing table.
if (getFieldDescs(hCur, &uNumFields, &fldDescSrc) != DBIERR_NONE)
{
rslt = DbiCloseCursor(&hCur);
ChkRslt(rslt, "CloseCursor");
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
return;
}
Screen("\r\n Close the %s table...", szTblName);
DbiCloseCursor(&hCur);
// Allocate enough space for the data passed to the callback function.
CallBackData = (pCHAR)malloc(100 * sizeof(CHAR));
if (CallBackData == NULL)
{
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
return;
}
// Register the callback.
rslt = DbiRegisterCallBack(NULL, cbRESTRUCTURE, (UINT32) CallBackData,
sizeof(RESTCbDesc), &CbInfo, CallBackFunc);
if(rslt!=DBIERR_NONE)
{
free(CallBackData);
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
return;
}
Screen(" Initialize the table descriptor...");
memset(&crTblDesc, 0, sizeof(CRTblDesc));
strcpy(crTblDesc.szTblName, szTblName);
strcpy(crTblDesc.szTblType, szTblType);
crTblDesc.bPack = TRUE;
changeFieldDescs(&uNumFields, fldDescSrc, fldDescDest, ecrFldOp);
crTblDesc.iFldCount = uNumFields;
crTblDesc.pecrFldOp = ecrFldOp;
crTblDesc.pfldDesc = fldDescDest;
Screen(" Restructure the %s table to the %s table...",
szTblName, szRstrctTblName);
rslt = DbiDoRestructure(hDb, 1, &crTblDesc, (pCHAR) szRstrctTblName,
szKeyViol, NULL, FALSE);
if (ChkRslt(rslt, "DoRestructure") != DBIERR_NONE)
{
free(CallBackData);
free(fldDescSrc);
DbiRegisterCallBack(hCur, cbRESTRUCTURE, NULL, 0, NULL, NULL);
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
return;
}
// Unregister the callback by passing in NULL for the function.
rslt = DbiRegisterCallBack(hCur, cbRESTRUCTURE, NULL, 0, NULL, NULL);
if (ChkRslt(rslt, "RegisterCallBack") != DBIERR_NONE)
{
free(CallBackData);
free(fldDescSrc);
rslt = DbiDeleteTable(hDb, (pCHAR) szRstrctTblName, (pCHAR) szTblType);
ChkRslt(rslt, "DeleteTable");
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
return;
}
Screen(" Open the %s table...", szRstrctTblName);
rslt = DbiOpenTable(hDb, (pCHAR) szRstrctTblName, (pCHAR) szTblType,
NULL, NULL, 0, dbiREADWRITE, dbiOPENSHARED,
xltFIELD, FALSE, NULL, &hCur);
if (ChkRslt(rslt, "OpenTable") != DBIERR_NONE)
{
free(CallBackData);
free(fldDescSrc);
rslt = DbiDeleteTable(hDb, (pCHAR) szRstrctTblName, (pCHAR) szTblType);
ChkRslt(rslt, "DeleteTable");
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
return;
}
rslt = DbiSetToBegin(hCur);
ChkRslt(rslt, "SetToBegin");
Screen(" Display the %s table...", szRstrctTblName);
DisplayTable(hCur, uNumOfRecs);
Screen("\r\n Close the %s table...", szRstrctTblName);
rslt = DbiCloseCursor(&hCur);
ChkRslt(rslt, "CloseCursor");
Screen(" Delete the %s restructured table...", szRstrctTblName);
rslt = DbiDeleteTable(hDb, (pCHAR) szRstrctTblName, (pCHAR) szTblType);
ChkRslt(rslt, "DeleteTable");
free(fldDescSrc);
free(CallBackData);
Screen(" Close the database and exit IDAPI...");
CloseDbAndExit(&hDb);
Screen("\r\n*** End of Example ***");
}
//===============================================================
// Function:
// getFieldDescs(hCur, *uNumFields, **fldDescSrc)
//
// Input: hCur - Handle to the cursor
// uNumFields - Number of fields in the field descriptor.
// (Returned)
// fldDescSrc - Existing field descriptor (Input)
//
// Return: IDAPI return code.
//
// Description:
// This function gets the field descriptor for an existing cursor
//================================================================
DBIResult getFieldDescs(hDBICur hCur, UINT16 *uNumFields, FLDDesc **fldDesc)
{
DBIResult rslt;
CURProps curProps;
// Change the translation mode to xltNONE to get the physical
// field descriptors.
rslt = DbiSetProp(hCur, curXLTMODE, xltNONE);
ChkRslt(rslt, "SetProp");
rslt = DbiGetCursorProps(hCur, &curProps);
if (ChkRslt(rslt, "GetCursorProps") != DBIERR_NONE)
{
return rslt;
}
*uNumFields = curProps.iFields;
*fldDesc = (FLDDesc *) malloc(curProps.iFields * sizeof(FLDDesc));
if (fldDesc == NULL)
{
return DBIERR_NOMEMORY;
}
rslt = DbiGetFieldDescs(hCur, *fldDesc);
if (ChkRslt(rslt, "GetFIeldDescs") != DBIERR_NONE)
{
return rslt;
}
// Change the translation mode back to xltFIELD.
rslt = DbiSetProp(hCur, curXLTMODE, xltFIELD);
ChkRslt(rslt, "SetProp");
return DBIERR_NONE;
}
//===============================================================
// Function:
// changeFieldDescs(uNumFields, FldDescSrc,
// fldDescDest, ecrFldOp);
//
// Input: uNumFields - Number of fields in the existing field descriptor
// Also returns the number of fields in the new
// field descriptor. (Input and Returned)
// fldDescSrc - Existing field descriptor (Input)
// fldDescDest - New field descriptor to use. (Returned)
// ecrFldOp - Array of operations on the fields in
// fldDescDest. (Returned)
//
// Return: IDAPI return code.
//
// Description:
// This function sets up the field structure for the new table.
//================================================================
DBIResult changeFieldDescs(UINT16 *uNumFields, FLDDesc *fldDescSrc,
FLDDesc *fldDescDest, CROpType *ecrFldOp)
{
UINT16 i;
for (i=0; i < NUMOFFIELDS; i++)
{
fldDescDest[i] = fldDescSrc[i];
ecrFldOp[i] = crNOOP;
}
*uNumFields = NUMOFFIELDS;
return DBIERR_NONE;
}
//======================================================================
// Name: CallBackFunc()
//
// Input: ecbType - Callback type
// iClientData - Pointer to client information that is passed into
// the callback function
// pCbInfo - The callback structure that holds the information
// about the current state
//
// Return: The action that should be taken
//
// Description:
// This function will be called from the BDE during the processing
// of the restructure.
//======================================================================
#ifdef __BORLANDC__
#pragma argsused
#endif
CBRType DBIFN
CallBackFunc (CBType ecbType, UINT32 iClientData, pVOID pCbInfo)
{
RESTCbDesc *eCBRestDesc; // Variable to contain passed in
// information
pCHAR pszMsg; // Information to be displayed.
#ifndef WIN32
// Set to stop a unused variable warning.
iClientData = iClientData;
#endif
switch (ecbType)
{
// In case this is a restructure progress callback display the
// information.
case cbRESTRUCTURE:
eCBRestDesc = (RESTCbDesc far *)pCbInfo;
// Restructuring the old field.
if(eCBRestDesc->eRestrObjType == restrOLDFLD)
{
pszMsg = (pCHAR)malloc(DBIMAXMSGLEN * sizeof(CHAR) + 1);
if (!pszMsg)
{
return cbrUSEDEF;
}
strcpy(pszMsg, eCBRestDesc->uObjDesc.fldDesc.szName);
Screen("\r\n### CallBack information: Deleting the %s "
"field...", pszMsg);
free(pszMsg);
}
else
{
// Restructuring the new table's index.
if(eCBRestDesc->eRestrObjType == restrNEWINDEX)
{
Screen("### CallBack information: Recreating the "
"Primary index...\r\n");
}
// Not one we are expecting.
else
{
Screen("### In the callback function");
}
}
break;
default:
Screen("### In the callback function");
}
return cbrUSEDEF;
}