Adapters expose a consistent interface to a persistent storage implementation. A Lawnchair build enqueues adapters and mixes in the first one valid for the current environment. This pattern is common in mobile scenarios, for example, a Lawnchair built with the DOM and Gears adapters will gracefully degrade through all available Android persistence solutions.
| touchdb-couchdb | sync your lawnchair data between devices and the cloud |
| blackberry-persistent-store | great for phonegap |
| dom | localStorage (often called dom storage) **default adapter** |
| window-name | oldest hack in the book **default fallback** |
| gears-sqlite | for android < 2.x |
| ie-userdata | for older versions of ie |
| webkit-sqlite | deprecated but still perhaps useful |
| indexed-db | the new direction of HTML5 (say that 3 times fast) |
| html5-filesystem | a persistent and sandboxed filesystem |
| memory | in memory reference implementation |
If you require an adapter that's not listed here it is trivial to implement your own. Adapters have the following interface:
:::JavaScript
// adapter name as a string
adapter
// boolean; true if the adapter is valid for the current environment
valid
// ctor call and callback. 'name' is the most common option
init ([options], callback)
// returns all the keys in the store
keys (callback)
// save an object
save (obj, callback)
// batch save array of objs
batch(array, callback)
// retrieve obj (or array of objs) and apply callback to each
get (key|array, callback)
// check if an obj exists in the collection
exists (key, callback)
// returns all the objs to the callback as an array
all (callback)
// remove a doc or collection of em
remove (key|array, callback)
// destroy everything
nuke (callback)
The tests ensure adapters are consistent no matter what the underlying store is. If you are writing an adapter check out ./tests/lawnchair-spec.js. The memory adapter is probably the simplest implementation to learn from. Note, all Lawnchair methods accept a callback as a last parameter. This is deliberate, most modern clientside storages only have async style interfaces, for a good reason, your code won't block the main thread aiding in the perception of performance. That callback will be scoped to the Lawnchair instance. Make use of fn and lambda methods to allow for terse callbacks.