# flat-cache

> A stupidly simple key/value storage using files to persist the data

## install

    npm i --save flat-cache

## Usage

    var flatCache = require('flat-cache')
    // loads the cache, if one does not exists for the given
    // Id a new one will be prepared to be created
    var cache = flatCache.load('cacheId');

    // sets a key on the cache
    cache.setKey('key', { foo: 'var' });

    // get a key from the cache
    cache.getKey('key') // { foo: 'var' }

    // fetch the entire persisted object
    cache.all() // { 'key': { foo: 'var' } }

    // remove a key
    cache.removeKey('key'); // removes a key from the cache

    // save it to disk
    cache.save(); // very important, if you don't save no changes will be persisted.
    // cache.save( true /* noPrune */) // can be used to prevent the removal of non visited keys

    // loads the cache from a given directory, if one does
    // not exists for the given Id a new one will be prepared to be created
    var cache = flatCache.load('cacheId', path.resolve('./path/to/folder'));

    // The following methods are useful to clear the cache
    // delete a given cache
    flatCache.clearCacheById('cacheId') // removes the cacheId document if one exists.

    // delete all cache
    flatCache.clearAll(); // remove the cache directory

## Motivation for this module

I needed a super simple and dumb in-memory cache with optional disk persistance in order to make a script that will beutify files with `esformatter` only execute on the files that were changed since the last run. To make that possible we need to store the `fileSize` and `modificationTime` of the files. So a simple `key/value` storage was needed and Bam! this module was born.

## Important notes

- If no directory is especified when the `load` method is called, a folder named `.cache` will be created inside the module directory when `cache.save` is called. If you're committing your `node_modules` to any vcs, you might want to ignore the default `.cache` folder, or specify a custom directory.
- The values set on the keys of the cache should be `stringify-able` ones, meaning no circular references
- All the changes to the cache state are done to memory
- I could have used a timer or `Object.observe` to deliver the changes to disk, but I wanted to keep this module intentionally dumb and simple
- Non visited keys are removed when `cache.save()` is called. If this is not desired, you can pass `true` to the save call like: `cache.save( true /* noPrune */ )`.

## License

MIT

## Changelog

changelog