lmdb-search v1.1.1

LMDB-search

This an interface to lmdb, containing several functions to facilitate the search for keys / values, and manipulate the data.

Features:

• increaseValue: Increase a key's value by one or more, if specified.
• increaseValueSync: Increase synchronously a key's value by one or more, if specified.
• decreaseValue: Decrease a key's value by one or more, if specified.
• decreaseValueSync: Decrease synchronously a key's value by one or more, if specified.
• list: Lists all of the keys, or all of the keys starting with a prefix if specifed.
• findOne: Search and retrieve a key and it's value, if an option is specified.
• findMany: Search and retrieve an array of keys and values, if an option is specified.

Get started

import Database from 'lmdb-search'
// or
const Database = require('lmdb-search');

// we setup the database
const db = new Database('path/to/folder');

// we create a key
db.setSync('key', 'value');

// we access to its value
db.get('key')
.then(value => {
  console.log(value);// 'value'
})

Docs

class Database(String path)

Returns an instance of the database.

const db = new Database('/path/fo/folder');

set(String key, Any value)

Returns a Promise

db.set('key', 'value')
.then((value) => {
  console.log(value);// 'value'
});

setSync(String key, Any value)

Returns the value of false if it failed.

const value = db.setSync('key', 'value');
console.log(value);// 'value'

findOne(Object options)

It will search a value that match the query (the where key in the options). The query is an object. In this object, you can specify some fields, that the value must have. For example, if you set in the query a value called name, and its value is John Doe, it will retrieve a value which has John Doe as value for the name key. On the other hand, you can specify many possible options. In your query, instead of setting a String as value of the name key, you can set an array, with different options, and it will match if a key's value has one of the options as value for the name key. But if the a value has a key called name, with an array as value, the query will match only if this array contains at least all the items in the query's name array.

In the query, if you specify an object in an array, it will be skipped.

/*
Example 1
*/
db.set('user', {
  name: 'John'
});

db.findOne({
  where: {
    name: 'John'
  }
}).then(/**/)// it will match

/*
Example 2
*/
*/
db.set('user', {
  name: 'John'
});

db.findOne({
  where: {
    name: ['John', 'Jane']
  }
}).then(/**/)// it will match

/*
Example 3
*/
db.set('user', {
  name: ['John', 'Doe']
});

db.findOne({
  where: {
    name: [['John', 'Jane'], 'Doe']
  }
}).then(/**/)// it will match

/*
Example 4
*/
db.set('user', {
  name: ['John', 'Doe']
});

db.findOne({
  where: {
    name: ['John', 'Jane', 'Doe']
  }
}).then(/**/)// it will NOT match

findOne query example

db.setSync('user1', {
  name: 'John',
  roles: ['user']
});
db.setSync('user2', {
  name: 'John',
  roles: ['user', 'admin']
});
db.setSync('user3', {
  name: 'Jane',
  roles: ['user', 'admin']
});

db.findOne({
  where: {
    name: 'John',
    roles: ['admin']
  }
})
  .then(({ key, value }) => {
    console.log(key);// 'user2'
    console.log(value);// { name: 'John', roles: ['user', 'admin'] }
  })

findMany(Object options)

The query works as above, but you can specify more things in the options, such as offset or limit (they are optionnal)

db.setSync('user1', {
  name: 'John',
  roles: ['user']
});
db.setSync('user2', {
  name: 'John',
  roles: ['user', 'admin']
});
db.setSync('user3', {
  name: 'Jane',
  roles: ['user', 'admin']
});

db.findMany({
  where: {
    name: 'John',
    roles: ['user']
  },
  offset: 0,
  limit: 5
})
  .then((arr) => {
    arr.forEach(({ key, value }) => {
      console.log(key);// user1 and user2
    })
  })

get(String key)

Returns a Promise

db.get('key')
.then(value => {
  console.log(value);
});

remove(String key)

Returns a Promise (true or false)

db.remove('key')
.then(isRemoved => {
  if (isRemoved) {
    console.log('Key removed.')
  } else {
    console.log('Operation failed.')
  }
});

removeSync(String key)

Returns a boolean.

const isRemoved = db.removeSync('key');

if (isRemoved) {
  console.log('Key removed.')
} else {
  console.log('Operation failed.')
}

getEntry(String key)

Returns a Promise

db.getEntry('key')
.then(entry => {
  console.log(entry)// { value: 'value' }
});

increaseValue(String key, Number rise?)

Returns a Promise

db.setSync('number', 1);

db.increaseValue('number')
.then(value => {
  console.log(value);// 2
});

db.increaseValue('number', 5)
.then(value => {
  console.log(value);// 7
});

increaseValueSync(String key, Number rise?)

Returns the new value

db.setSync('number', 1);

let newValue = db.increaseValueSync('number');
console.log(newValue);// 2


newValue = db.increaseValueSync('number', 5);
console.log(newValue);// 7

decreaseValue(String key, Number rise?)

Returns a Promise

db.setSync('number', 10);

db.decreaseValue('number')
.then(value => {
  console.log(value);// 9
});

db.decreaseValue('number', 4)
.then(value => {
  console.log(value);// 5
});

decreaseValueSync(String key, Number rise?)

Returns the new value

db.setSync('number', 10);

let newValue = db.decreaseValueSync('number');
console.log(newValue);// 9


newValue = db.decreaseValueSync('number', 4);
console.log(newValue);// 5

ifNoExists(String key, Function callback)

Return a Promise

db.ifNoExists('random-key', () => {
  console.log("The 'random-key' key doesn't exists.");
});

transaction(Function callback)

Returns a Promise

db.transaction(() => {
  let value = db.get('number');
  value += 1;
  db.setSync('number', value);
  return true;// succeded
});

transactionSync(Function callback)

Quite the same than before.

getRange(Object options)

Returns an Iterable. The limit and the offset are optionnals.

db.getRange({ 
  start: 'key1', 
  end: 'key5', 
  limit: 10, 
  offset: 0 
})
	.filter(({ key, value }) => test(key))
	.forEach(({ key, value }) => {
		// for each key-value pair in the given range that matched the filter
	});

getKeys(Object options)

Same as getRange, but it returns only the keys.

list(String prefix?)

Returns an Array.

db
  .list()
  .forEach(key => {
    console.log(key);
  });

db
  .list('user-')
  .forEach(key => {
    console.log(key);// user-...
  })

close()

Close the current database;

doesExist(String key)

Returns a boolean

db.setSync('custom-key', 'custom-value');

console.log( db.doesExist('custom-key') );// true
console.log( db.doesExist('random-key') );// false

getBinary(String key)

Returns a Buffer (the binary data for the given key)

getMany(Array keys)

Asynchronously returns the values for the given keys.

clearAsync()

Asynchronously removes all the entries in the database.

clearSync()

Synchronously removes all the entries in the database.

drop()

Asynchronously removes all the entries in the database, and the database too.

dropSync()

Synchronously removes all the entries in the database, and the database too.