keyv-nedb-core/README.md

nedb-core adapter for keyv

# keyv-nedb-core

[nedb-core](https://github.com/nedbhq/nedb-core) storage adapter for Keyv

Needs testing!


## Install

```shell
npm install --save keyv keyv-nedb-core
```

## Usage

```js
const Keyv = require('keyv')
const KeyvNedbAdapter = require('keyv-nedb-core')

let adapter = new KeyvNedbAdapter({
    filename: path.resolve('/path/to/myDatabase.db'),
    autoload: true
})

const keyv = new Keyv({store: adapter})
```

The options passed to the `KeyvNedbAdapter` constructor are passed straight to `nedb-core`'s Datastore constructor, unmodified.

The datastore is exposed on the adapter as `.nedb`:

```js
adapter.nedb.findOne({key: 'somekey'}, (err, doc) => console.log(doc))
```

You can run any of `nedb-core`'s methods.


## Removing expired keys

The adapter exposes one function called `evictExpired` which accepts no arguments and returns a promise that resolves with the value `true` once all expired keys have been removed from the cache. In order to make this work, the adapter must be able to deserialize your data.

If you're using keyv's default deserializer `json-buffer` this function will work out of the box. If you provided your own deserializer, pass it to the constructor as a separate parameter after nedb's options:

```js
const Keyv = require('keyv')
const KeyvNedbAdapter = require('keyv-nedb-core')
const moment = require('moment') // date manipulation lib

function deserialize (str) {
  let obj = JSON.parse(str)
  // convert a String to a Date:
  obj.creationDate = moment(obj.creationDate, 'DD/MM/YYYY').toDate()
  return obj
}

const nedbOptions = {
    filename: path.resolve('/path/to/myDatabase.db'),
    autoload: true
}

let adapter = new KeyvNedbAdapter(nedbOptions, deserialize)

const keyv = new Keyv({store: adapter, deserialize: deserialize})

// [...]

adapter.evictExpired().then(() => console.log('All cleaned up!'))

```

You can enable the automated eviction of expired keys. In the `options` object include the key `automaticEviction` and set it to a number higher than zero. The eviction will be run every time an internal counter reaches that number; the counter increases by 1 every time you do a `set`, `get` or `delete` and it's reset to zero when you `clear`. So if you set `automaticEviction` to 2000 and use `get` 4000 times, the function will run twice.

## License

MIT