Current version

[matchbox "0.0.9"]

Features

Matchbox offers more than just bindings:

Atom/Zipper/Cursor-ish abstraction over Firebase references
Clojure data in/out
Uniform API for JVM and JS platforms
Optional sequence abstraction - work with lists not sorted maps
Optional core.async based API
Multiplexed children event channels and/or callbacks
Registry for listeners simplifies scoped or global cleanup

Usage

Quick spin to get some basic flavour:

(require '[matchbox.core :as m])

(def root (m/connect "https://<app>.firebaseio.com"))

(m/auth-anon root)

(m/listen-children
  root [:users :mike :friends]
  (fn [[event-type data]] (prn data)))

(def mikes-friends (m/get-in root [:users :mike :friends]))
(m/reset! mikes-friends [{:name "Kid A"} {:name "Kid B"}])
(m/conj! mikes-friends {:name "Jean"})

(m/deref
  mikes-friends
  (fn [key value]
    (m/reset-in! root [:users :mike :num-friends]
                 (count value))))

(m/unauth)

Take a look at the quick intro to for a lightning tour.

For those who want to dive right in, reagent-figwheel has a +firebase option bake some sensible Matchbox plumbing right into your next app.

Overview

For brevity, comparing to the JS Firebase API only.

Notes:

Almost all functions accept callbacks, and those callbacks will be intercepted to receive hydrated data.
This list is not complete, notably it does not cover connectivity control and hooks, queries, auth, logging and other aspects also wrapped by Matchbox.

Matchbox	Firebase.js	Differences
`connect`	`Firebase.`	Supports optional korks as second parameter
`get-in`	`.child`	Supports symbols, keywords and sequences also (korks)
`parent`	`.parent`	-
`deref`	`.once`	Fixed to a "value" subscription
`deref-list`	`.once`	Returns ordered values rather than a map. Query compatible.
`reset!`	`.set`	Data automatically serialized in a sensible manner
`reset-with-priority!`	`.setWithPriority`	..
`merge!`	`.update`	..
`conj!`	`.push`	..
`swap!`	`.transaction`	Always applied locally, supports additional arguments.
`dissoc!` or `remove!`	`.remove`	-
`set-priority!`	`.setPriority`	-
`listen-to`	`.on`	Stored in registry for easy unsubscription
`listen-list`	`.on`	Like `deref-list` for `listen-to`
`listen-children`	`.on`	Listen to all child events, multiplexed.

Additionally, there are up to three variations of most functions:

*-in variants take an optional second parameter of korks, to refer directly to a child. These exist for all "ending-with-a-bang" functions, as well as deref and deref-list.
*< variants return a channel of results instead of taking a callback. These exist for all functions that would take a callback.
*-in< combine decoration of (1) and (2), and exist where applicable.

The last two, if they exist are defined in matchbox.async. This is so that Matchbox can be used without a core.async dependency.

Examples

1) There are some ClojureScript demos in the examples directory.

Those in the cljs folder can be compiled from the main project via lein cljsbuild once <example-name>, and then run by opening the 'index.html' found in the example directory in a browser.

2) There is also a stand-alone demo project, reagent-example. This example can be launched by executing lein run, and opening "http://localhost:3000" in a browser.

3) If you'd like to use re-frame, there is a realtime chat app showcase.

Gotchas

swap! takes callback in non-standard way

Since we support passing additional arguments to an update function, we can't use an optional argument for the callback.

Our solution draws inspiration from "kwargs" style signatures:

(eg. `(my-function :has "keyword" :style "arguments")`).

Coming back to swap!, we support :callback callback-fn at end of arg list:

(m/swap! r f)                  ;; call (f <val>),     no callback
(m/swap! r f b c)              ;; call (f <val> b c), no callback
(m/swap! r f :callback cb)     ;; call (f <val>),     with callback `cb`
(m/swap! r f b c :callback cb) ;; call (f <val> b c), with callback `cb`

Note that :callback MUST appear as the second-last argument.

JVM callbacks on side thread

Depending on your environment and config, callbacks may be triggered on another thread.

This can be confusing when debugging with prn in callbacks, as *out* will not be to the REPL's writer. We provide matchbox.utils/prn as a simple helper to ensure output is visible.

Serialization

Data	Storage	Reads back as it writes?
`{}`, nameable keys	JSON	Not unless all keys are keywords (rest are coerced)
`{}`, richer keys	Not supported	N/A
`[]`	JSON with numeric keys	Yes
`#{}`	JSON with numeric keys	No, reads back as a vector
`"string"`	string	Yes
`:a/keyword`	":a/keyword"	Yes
Number	Number	Pretty much, with nits for `java.math.*` types
Record	JSON	No, reads back as vanilla map
(def)Type	JSON	No, reads back as vanilla map
Other	Depends on platform	Expect useless strings (JS) or serious downcasting (JVM)