I am right at the last stage of the development cycle of a form I am writing
for my new job and I have hit a major snag.
Database access :<
What I want to do is simple, I want to access a .pdb database, do a binary
search to find a record with the corresponding prodno unique id. I have never
accessed a database on a palm before, this all a first for me and I seem to be
so close.
What I get at this stage is a seemingly valid dbID of like 8552589 or
something, a dbP that has the same value as my eventP and formP (I'm not sure
if that means I am not connecting right) a recordNumber (or Index) of 1(not
desired), and a bunch of completely insane values in my pointer record and
basic record.
So dbID and dbP seem to be working, while DmFindSortPosition and possibly my
method of reading from the record handle are faulty. I really can't pinpoint it!
Here is some relevent code: (Not copy and pasted, so ignore simple typos)
//My Record Structure
typedef struct
{
char prodno[21];
char upc[21];
char retail[11];
etc. (all char values of correct size)
}UPCD;
//My Database Access (I am positive I have the correct db name)
LocalID dbID = DmFindDatabase(0, "Detail-PMOO");
DmOpenRef dbP = DmOpenDatabase(0, dbID, dmModeReadOnly);
//The Comparison Function for the DmFindSortPosition(I am very unconfident in
this function and based it exactly off of an example function I found in two
locations on the internet)
static int CompareRecordFunc(UPCD *rec1, UPCD *rec2, int unusedInt,
SortRecordInfoPtr unused1, SortRecordInfoPtr unused2, int appInfoH)
{
int result;
result = StrCompare(rec1->prodno, rec2->prodno);
return result
}
//The Binary Search
UPCD FindRecord;
UPCD *Record;
StrCopy(FindRecord.prodno ,"00000000011");
UInt32 recordNumber = DmFindSortPosition(dbP, &FindRecord, 0, (DmComparF *)
CompareRecordFunc, 0);
if (recordNumber > 0) {
MemHandle recH;
recH = DmQueryRecord(dbP, recordNumber - 1);
Record = (UPCD *) MemHandleLock(recH);
Boolean foundIt = StrCompare(FindRecord.prodno, Record->prodno);
MemHandleUnlock(recH); }
if (foundIt) {
SetFieldText( MainDescriptionField, Record->prodno, 30, true);
}
//Then close database and that's it.
I think the possible problem areas are in the comparison function, making
Record = the memhandle, opening the database(somehow, it doesn't error and dbID
seems valid.
Another issue is packing, I don't understand what packing and unpacking
databases means. Do you have to unpack a database to read records from it?
That's all I can think of, thank you for any help you give me, this is SO very
appreciated.
, Jamie
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