sembast 1.15.2

  • README.md
  • CHANGELOG.md
  • Example
  • Installing
  • Versions
  • 96

sembast.dart #

sembast db stands for Simple Embedded Application Store database

Build Status

General #

Yet another NoSQL persistent store database solution for single process io applications. The whole document based database resides in a single file and is loaded in memory when opened. Changes are appended right away to the file and the file is automatically compacted when needed.

Works on Dart VM and Flutter (no plugin needed, 100% Dart). Inspired from IndexedDB, DataStore, WebSql, NeDB, Lawndart...

Supports encryption using user-defined codec.

Usage #

Opening a database #

A database is a single file represented by a path in the file system

// File path to a file in the current directory
String dbPath = 'sample.db';
DatabaseFactory dbFactory = databaseFactoryIo;

// We use the database factory to open the database
Database db = await dbFactory.openDatabase(dbPath);

The db object is ready for use.

Simple put/get records #

For quick usage, data can be written and read quickly using the put/get/delete api on the database object

// Easy to put/get simple values or map
// A key can be anything (int, String) as long is it can
// be properly JSON encoded/decoded
await db.put('Simple application', 'title');
await db.put(10, 'version');
await db.put({'offline': true}, 'settings');

// read values
String title = await db.get('title') as String; 
int version = await db.get('version') as int;
Map settings = await db.get('settings') as Map;
  
// ...and delete
await db.delete('version');

Record fields can be reference using a dot (.) unless escaped

For example

var value = record['path.sub'];
// means value at {'path': {'sub': value}}
value = record[FieldKey.escape('path.sub')];
// means value at {'path.sub': value}

Follow the links with more informatin on how to write or read data

Auto increment #

If no key is provided, the object is inserted with an auto-increment value

// Auto incrementation is built-in
int key1 = await db.put('value1') as int;
int key2 = await db.put('value2') as int;
// key1 = 1, key2 = 2...

Transaction #

Actions can be group in transaction for consistency and optimization (single write on the file system). If an error is thrown, the transaction is cancelled and the changes reverted.

To prevent deadlock, never use an existing Database or Store object.

await db.transaction((txn) async {
  await txn.put('value1');
  await txn.put('value2');
});

More info on transaction here

Using the new Store API #

The new API takes advantage of strong mode to make database access less error prone.

// Use the main store for storing key values as String
var store = StoreRef<String, String>.main();

// Writing the data
await store.record('username').put(db, 'my_username');
await store.record('url').put(db, 'my_url');

// Reading the data
var url = await store.record('url').get(db);
var username = await store.record('username').get(db);

More info on the new API here

Store #

The store has some similarities with IndexedDB store and DataStore entities. The database always has a main store for easy access (like in the example aboves or typically to save singletons) and allows for an infinite number of stores where a developer would store entity specific data (such as list of record of the same 'type')

 // Use the animals store using Map records with int keys
var store = intMapStoreFactory.store('animals');

// Store some objects
await db.transaction((txn) async {
  await store.add(txn, {'name': 'fish'});
  await store.add(txn, {'name': 'cat'});
  
  // You can specify a key
  await store.record(10).put({'name': 'dog'});
});
 

Simple find mechanism #

Filtering and sorting can be done on any field

More information here

 // Use the animals store using Map records with int keys
var store = intMapStoreFactory.store('animals');

// Store some objects
await db.transaction((txn) async {
  await store.add(txn, {'name': 'fish'});
  await store.add(txn, {'name': 'cat'});
  await store.add(txn, {'name': 'dog'});
});

// Look for any animal "greater than" (alphabetically) 'cat'
// ordered by name
var finder = Finder(
    filter: Filter.greaterThan('name', 'cat'),
    sortOrders: [SortOrder('name')]);
var records = await store.find(db, finder: finder);

expect(records.length, 2);
expect(records[0]['name'], 'dog');
expect(records[1]['name'], 'fish');

Codec and encryption #

Sembast supports using a user-defined codec to encode/decode data when read/written to disk. It provides a way to support encryption. Encryption itself is not part of sembast but an example of an xxtea based encryption is provided in the test folder:

// Initialize the encryption codec with a user password
var codec = getXXTeaSembastCodec(password: '[your_user_password]');

// Open the database with the codec
Database db = await factory.openDatabase(dbPath, codec: codec);

// ...your database is ready to use as encrypted

More information here

idb_shim #

The project idb_shim provides a shim allowing accessing it using the IndexedDB api. The benefit is to be able to write the logic/synchronization part of the database layer and test its algorithms using Dart VM and not Dartium

// Idb factory based on sembast
var idbFactory = IdbSembastFactory(databaseFactoryIo);

String store = "my_store";

// Here the indexed db API can be used
void _initializeDatabase(VersionChangeEvent e) {
  Database db = e.database;
  // create a store
  ObjectStore objectStore = db.createObjectStore(store);
}
Database db = await idbFactory.open(dbPath, version: 1, onUpgradeNeeded: _initializeDatabase);

Transaction transaction = db.transaction(store, IDB_MODE_READ_WRITE);
ObjectStore objectStore = transaction.objectStore(store);

// put and read on object
await objectStore.put("value", "test");
expect(await objectStore.getObject("test"), "value");

await transaction.completed;

Information #

Storage format #

Data is stored in a text file where each line is (json format) either:

  • meta information of the database (first line)
  • record data

Each data written is appended lazily to the file for best performance. Compact might happen at any moment to prevent record duplication. The whole compact information is done in a new file followed by a rename to make it atomic.

Supported types #

Supported types depends on JSON supported types. More information here

Keys #

Supported key types are:

  • int (default with autoincrement when no key are passed)
  • String (String keys can also be generated à la firestore)
  • double

Values #

Supported value types are:

  • String.
  • num (int and double)
  • Map
  • List
  • bool
  • null

Build status #

Travis: Build Status

1.15.2 #

  • Add the ability to escape keys with dot in their names for updates and queries (filter, sort)
  • Fix codec signature check to compare the decrypted value instead of the encrypted one

1.15.1 #

  • Add custom filter support and allow filtering on list content for Filter.equals and Filter.matches

1.15.0 #

  • Add new API to allow strict typing on keys and values

1.14.0 #

  • Make the database work in cooperate mode to avoid stuttering with big databases on Flutter
  • Commit changes lazily to the storage

1.13.3 #

  • Add support for user-defined codec to allow encryption

1.13.0 #

  • Add support for nested dotted fields, i.e. 'path.sub' allow setting/getting/filtering/sorting on path inner value sub
  • support for boundaries (start and end) in a query with sort orders

1.12.0 #

  • Add Filter.matchs for regular expression filtering
  • Add rootPath support for DatabaseFactoryIo to allow relative path to a root folder

1.10.1 #

  • Add update method to allow updating partially a Map record
  • Add updateRecords utility methods to update multiple records based on a a filter
  • properly clone each value when written and read

1.9.5 #

  • Fix database manipulation issues during onVersionChanged

1.9.4 #

  • Add value_utils to help comparing value and arrays

1.9.1 #

  • New transaction API
  • dart2 only

1.8.0 #

  • fix flutter cast issue
  • fix limit/offset implementation
  • Update synchronized dependency
  • make all constants lowercase

1.7.0 #

  • mode databaseModeNeverFails is the new default
  • API cleanup and add deprecations

1.6.1 #

  • Add implicit-cast: false support

1.6.0 #

1.5.0 #

  • Update synchronized dependency
  • Add DatabaseMode.NEVER_FAILS that will ignore the file once a corrupted record is encountered

1.3.9 #

  • Add web example to test ddc support
  • Fix transaction

1.3.7 #

  • Strong mode support
  • support for setting record field directly
  • fix support for dart 1.24

1.3.1 #

  • Add support for import/export

1.2.2 #

  • Add for support for isNull and notNull filter
  • Add for support for sorting null last
  • Travis test integration

1.0.0 #

  • Initial revision

example/main.dart

// basically same as the io runner but with extra output
import 'dart:async';

import 'package:path/path.dart';
import 'package:sembast/sembast.dart';
import 'package:sembast/sembast_io.dart';

Future main() async {
  Database db = await databaseFactoryIo
      .openDatabase(join(".dart_tool", "sembast", "example", "record_demo.db"));
  Store store = db.getStore("my_store");
  Record record = Record(store, {"name": "ugly"});
  record = await db.putRecord(record);
  record = await store.getRecord(record.key);
  record =
      (await store.findRecords(Finder(filter: Filter.byKey(record.key)))).first;
  record = await store.getRecord(record.key);
  print(record);
  var records =
      (await store.findRecords(Finder(filter: Filter.matches("name", "^ugl"))));
  print(records);
}

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  sembast: ^1.15.2

2. Install it

You can install packages from the command line:

with pub:


$ pub get

with Flutter:


$ flutter packages get

Alternatively, your editor might support pub get or flutter packages get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:sembast/sembast.dart';
  
Version Uploaded Documentation Archive
1.15.2 Apr 16, 2019 Go to the documentation of sembast 1.15.2 Download sembast 1.15.2 archive
1.15.1 Mar 12, 2019 Go to the documentation of sembast 1.15.1 Download sembast 1.15.1 archive
1.15.0 Mar 11, 2019 Go to the documentation of sembast 1.15.0 Download sembast 1.15.0 archive
1.14.0+3 Mar 7, 2019 Go to the documentation of sembast 1.14.0+3 Download sembast 1.14.0+3 archive
1.14.0+2 Mar 1, 2019 Go to the documentation of sembast 1.14.0+2 Download sembast 1.14.0+2 archive
1.14.0+1 Mar 1, 2019 Go to the documentation of sembast 1.14.0+1 Download sembast 1.14.0+1 archive
1.14.0 Feb 26, 2019 Go to the documentation of sembast 1.14.0 Download sembast 1.14.0 archive
1.13.3+1 Feb 12, 2019 Go to the documentation of sembast 1.13.3+1 Download sembast 1.13.3+1 archive
1.13.3 Feb 8, 2019 Go to the documentation of sembast 1.13.3 Download sembast 1.13.3 archive
1.13.2 Jan 16, 2019 Go to the documentation of sembast 1.13.2 Download sembast 1.13.2 archive

All 58 versions...

Popularity:
Describes how popular the package is relative to other packages. [more]
93
Health:
Code health derived from static analysis. [more]
100
Maintenance:
Reflects how tidy and up-to-date the package is. [more]
100
Overall:
Weighted score of the above. [more]
96
Learn more about scoring.

We analyzed this package on Apr 24, 2019, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.2.0
  • pana: 0.12.14

Platforms

Detected platforms: Flutter, web, other

No platform restriction found in primary library package:sembast/sembast.dart.

Dependencies

Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.1.0-dev <3.0.0
logging >=0.11.3 <3.0.0 0.11.3+2
meta >=1.1.6 <3.0.0 1.1.7
path >=1.5.1 <3.0.0 1.6.2
synchronized >=2.1.0 <4.0.0 2.1.0
Dev dependencies
build_runner >=0.9.0
build_test >=0.10.2+5
build_web_compilers >=0.4.0+4
dev_test >=0.13.0+3
pedantic >=1.4.0
process_run >=0.10.0+1
test >=1.5.1
xxtea >=2.0.2