LazyDb

This is an object-oriented lazy loading DB for Node.js. node-lmdb is used as storage. Principle: you create an instance of object with unique ID, connected to the DB. Object is empty on start. Reading and writing the properties of this object is transparently converted to DB read and writes. After accessing a property, it will be synchronized with DB automatically.

Example

const lazyDb = require('.');

// connect to the environment and DB
var env = lazyDb.open({
    path: './data'
});

var dbi = env.openDbi({
   name: 'test',
   create: true
});

// create lazy object for write
var obj1 = lazyDb.write('MyId1', dbi);

// write properties
obj1.foo = 'Hello world!';
obj1.foo2 = 12345;
obj1.example = {
    key1: 'abcde',
    key2: 123123,
    key3: {
        subKey1: 'xyz',
        subKey2: -12
    }
};
obj1.array = [1, 2, 3];
delete obj1.arr;


// create lazy object with cache for read
var obj = lazyDb.read('MyId1', dbi, null, true);

console.log('Object (MyId1):');
console.log('---------------------');

// look at the keys
console.log('object on start:', obj); // see it is not loaded yet
console.log('object keys:', Reflect.ownKeys(obj)); // but it have keys
console.log('');

// access some properties
console.log('foo:', obj.foo);
console.log('foo2:', obj.foo2);

console.log('example:', obj.example);
console.log('example.key3 keys:', Reflect.ownKeys(obj.example.key3));
console.log('example.key2:', obj.example.key2);
console.log('example.key3:', obj.example.key3.subKey1);

console.log('array:', obj.array);
console.log('array keys:', Reflect.ownKeys(obj.array));
console.log('array[0]:', obj.array[0]);
console.log('array[2]:', obj.array[2]);
console.log('');

console.log('object on finish:', obj);
console.log('');

// get sub-object from property `example`
var subObj = lazyDb.read('MyId1.example', dbi, null, true);
console.log('Sub object (MyId1.example):');
console.log('---------------------');

console.log('key2:', subObj.key2);
console.log('key3.subKey1:', subObj.key3.subKey1);
console.log('key3 keys:', Reflect.ownKeys(subObj.key3));
console.log('');

console.log('Sub object on finish:', subObj);
console.log('');

var subObj2 = lazyDb.read('MyId1.foo', dbi, null, true);
console.log('Direct value:');
console.log('---------------------');
console.log('MyId1.foo:', subObj2);

console.log('\nDB:');
lazyDb.printDb(dbi);

dbi.close();
env.close();

API

open

lazyDb.open(Object options) -> Object

Open LMDB environment. options.path is direcory for db (required). Returns environment object, which have method to open and create database. See node-lmdb docs for options.

Example:

// connect to the environment and DB
var env = lazyDb.open({
    path: './data'
});

var dbi = env.openDbi({
   name: 'test',
   create: true
});

read

lazyDb.read(String key, Object dbi, [Object txn], [Boolean cache]) -> Proxy|*

Read value from database directly or create proxy object by key. If transaction txn is passed, object will use it, otherwise internal transaction(s) will be started. When cache is true, values from DB are set to object's properties (cached). In this case reading from database is performed once on first property access. Returned object can be modified, but nothing will be written to database.

write

lazyDb.write(String key, Object dbi, [Object txn]) -> Proxy

Create object connected to database dbi with unique key key. If transaction txn is passed, object will use it, otherwise internal transaction(s) will be started. When properties of returned object are modified, they are automatically stored in database.

del

lazyDb.del(String key, Object dbi, [Object txn])

Remove value or object from DB by key. If transaction txn is passed, object will use it, otherwise internal transaction(s) will be started.

printDb

lazyDb.printDb(Object dbi, [Number skip = 0], [Number limit = 100])

Prints content of db to console.

druide / lazy-object-db