get method

Future<List<int>?> get(Pointer<MDB_txn> txn, String key, { String? dbName, LMDBFlagSet? flags, })

Retrieves a raw byte value from the database.

Parameters:

• txn - Active transaction
• key - Key to retrieve
• dbName - Optional named database. If not provided, the default database will be used.
• flags - Optional operation flags

Returns the value as byte list, or null if not found.

Example:

final txn = await db.txnStart(flags: LMDBFlagSet()..add(MDB_RDONLY));
try {
  final bytes = await db.get(txn, 'key');
  if (bytes != null) {
    print('Value: $bytes');
  }
  await db.txnCommit(txn);
} catch (e) {
  await db.txnAbort(txn);
  rethrow;
}

Implementation

Future<List<int>?> get(
  Pointer<MDB_txn> txn,
  String key, {
  String? dbName,
  LMDBFlagSet? flags,
}) async {
  if (!isInitialized) throw StateError(_errDbNotInitialized);

  final dbi = await _getDatabase(txn, name: dbName, flags: flags);
  final keyPtr = key.toNativeUtf8();

  try {
    return _withAllocated<List<int>?, MDB_val>((keyVal) {
      return _withAllocated<List<int>?, MDB_val>((dataVal) {
        keyVal.ref.mv_size = keyPtr.length;
        keyVal.ref.mv_data = keyPtr.cast();

        final result = _lib.mdb_get(
          txn,
          dbi,
          keyVal,
          dataVal,
        );

        if (result == 0) {
          final data = dataVal.ref.mv_data.cast<Uint8>();
          return data.asTypedList(dataVal.ref.mv_size).toList();
        } else if (result == MDB_NOTFOUND) {
          return null;
        } else {
          throw LMDBException('Failed to get data', result);
        }
      }, calloc<MDB_val>());
    }, calloc<MDB_val>());
  } finally {
    calloc.free(keyPtr);
  }
}