Scarlet Dame pleasetrythisathome

2015-01-29 Unofficial Relay FAQ

Compilation of questions and answers about Relay from React.js Conf.

Disclaimer: I work on Relay at Facebook. Relay is a complex system on which we're iterating aggressively. I'll do my best here to provide accurate, useful answers, but the details are subject to change. I may also be wrong. Feedback and additional questions are welcome.

What is Relay?

Relay is a new framework from Facebook that provides data-fetching functionality for React applications. It was announced at React.js Conf (January 2015).

	;; setup db to test with
	;; note that this setup uses a local dev transactor
	;; you can use a different transactor, but you cannot
	;; use a mem db because it does not support the log API
	(require '[datomic.api :as d])
	(def uri "datomic:dev://localhost:4334/reified-txes")
	(d/delete-database uri)
	(d/create-database uri)
	(def conn (d/connect uri))

	(ns plumbing.resource
	(:refer-clojure :exclude [with-open])
	(:require
	[schema.core :as s]
	[plumbing.core :as plumbing]
	[plumbing.fnk.pfnk :as pfnk]
	[plumbing.fnk.schema :as schema]
	[plumbing.graph :as graph]
	[plumbing.logging :as log]
	[plumbing.map :as map]

	(in-ns test
	(:require
	[schema.macros :as macros]
	[schema.utils :as sutils]))

	;; Wrapper type needed because Entity values do not implement
	;; IPersistentMap interface
	(defrecord EntitySchema
	[schema]
	Schema

	(ns node-test.core
	(:require [cljs.nodejs :as nodejs]))

	(nodejs/enable-util-print!)
	(def cp (.-spawn (nodejs/require "child_process")))

	(defn run-cmd [cmd args call-back]
	(let [child (cp cmd args)]
	(.on (.-stdout child) "data" call-back)
	(.on (.-stdout child) "end" #(println (str cmd " process ended")))))

	(comment ; Fun with transducers, v2

	;; Still haven't found a brief + approachable overview of Clojure 1.7's new
	;; transducers in the particular way I would have preferred myself - so here goes:

	;;;; Definitions
	;; Looking at the `reduce` docstring, we can define a 'reducing-fn' as:
	(fn reducing-fn ([]) ([accumulation next-input])) -> new-accumulation
	;; (The `[]` arity is actually optional; it's only used when calling
	;; `reduce` w/o an init-accumulator).

	(ns om-data.core
	(:require [om.core :as om :include-macros true]
	[om.dom :as dom :include-macros true]
	[datascript :as d]))

	(enable-console-print!)

	(def schema {})
	(def conn (d/create-conn schema))

	;; Datomic example code

	;; demonstrates various update scenarios, using a news database
	;; that contains stories, users, and upvotes

	;; grab an in memory database
	(use '[datomic.api :only (q db) :as d])
	(def uri "datomic:mem://foo")
	(d/create-database uri)
	(def conn (d/connect uri))

	platforms/
	plugins/