leveldb 7.0.0

Dart bindings for the LevelDB key value store. LevelDB is a fast key/value data store which supports arbitrary byte arrays as both keys and values.

example/main.dart

import 'dart:async';
import 'dart:typed_data';

import 'package:leveldb/leveldb.dart';

/// main example.
Future<dynamic> main() async {
  // Open a database. It is created if it does not already exist. Only one process can
  // open a database at a time.
  LevelDB<String, String> db = await LevelDB.openUtf8("/tmp/testdb");

  // By default keys and values are strings.
  db.put("abc", "def");

  // Now get the key
  String? value = db.get("abc");
  print("value is $value"); // value2 is def

  // Delete the key
  db.delete("abc");

  // If a key does not exist we get null back
  String? value3 = db.get("abc");
  print("value3 is $value3"); // value3 is null

  // Now lets add a few key-value pairs
  for (int i in new Iterable<int>.generate(5)) {
    db.put("key-$i", "value-$i");
  }

  // Iterate through the key-value pairs in key order.
  for (LevelItem<String, String> v in db.getItems()) {
    print(
        "Row: ${v.key} ${v.value}"); // prints Row: key-0 value-0, Row: key-1 value-1, ...
  }

  // Iterate keys between key-1 and key-3
  for (LevelItem<String, String> v in db.getItems(gte: "key-1", lte: "key-3")) {
    print(
        "Row: ${v.key} ${v.value}"); // prints Row: key-1 value-1, Row: key-2 value-2, Row: key-3 value-3
  }

  // Iterate explicitly. This avoids allocation of LevelItem objects if you never call it.current.
  LevelIterator<String, String> it = db.getItems(limit: 1).iterator;
  while (it.moveNext()) {
    print("${it.currentKey} ${it.currentValue}");
  }

  // Just key iteration
  for (dynamic key in db.getItems().keys) {
    print("Key $key"); // Prints Key key-0, Key key-1, ...
  }

  // Value iteration
  for (dynamic value in db.getItems().values) {
    print("Value $value"); // Prints Key value-0, Key value-1, ...
  }

  // Close the db. This free's all resources associated with the db.
  // All iterators will throw if used after this call.
  db.close();

  // Open a new db which will use raw UInt8List data. This is faster since it avoids any decoding.
  LevelDB<Uint8List, Uint8List> db2 =
      await LevelDB.openUint8List("/tmp/testdb");

  for (LevelItem<Uint8List, Uint8List> item in db2.getItems()) {
    print("${item.key}"); // Prints [107, 101, 121, 45, 48], ...
  }

  db2.close();
}