Custom File Formats
If you are going to support your own
file format in your conduit, then you’ll need to override two
routines in your subclass of CPcMgr
:
StoreDB
and RetrieveDB
. The
first will save the in-memory list of records to your format. The
second will read from your format, creating records and adding them
to the in-memory list.
We’d always suggest writing StoreDB
first,
if for no other reason than you can test it without having written
RetrieveDB
. This is because the Generic Conduit
Framework won’t call your RetrieveDB
routine if there’s no file in the user’s directory.
Therefore, as long as you keep deleting the file between syncs, you
can test your StoreDB
to your heart’s
content.
Note that when StoreDB
is called, the sync has
already taken place and all of the following actions have occurred:
Modified records have been copied between the handheld and the in-memory list (maintained by the Generic conduit).
Records whose deleted bits were set have been deleted.
All the records are clean (the dirty and deleted bits are not set).
The StoreDB Routine
Example 16-1 shows the outline of a
StoreDB
routine.
long CMyConduitPcMgr::StoreDB(void) { if ( !m_bNeedToSave) { // If no changes, don't waste time saving. return 0; } long err = Open( ); if (err) return GEN_ERR_UNABLE_TO_SAVE; for (DWORD dwIndex = 0; (dwIndex < m_dwMaxRecordCount) && (!err); dwIndex++) { if (!m_pRecordList[dwIndex]) continue; ...
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