#lang pollen
 

 ◊section[#:headline "Routedux — Routes the Redux Way"]{

 ◊img[#:alt "Route Dux" #:src "https://upload.wikimedia.org/wikipedia/commons/thumb/d/da/Ducks_crossing_the_road_sign.png/92px-Ducks_crossing_the_road_sign.png" #:align "right"]

 ◊a[#:href "https://badge.fury.io/js/routedux"]{◊img[#:src "https://badge.fury.io/js/routedux.svg"]}
 ◊a[#:href "https://travis-ci.org/cjdev/routedux"]{◊img[#:alt "Build Status" #:src "https://travis-ci.org/cjdev/routedux.svg?branch=master"]}

 
 Routedux routes URLs to Redux actions and vice versa.
 
 Your application doesn't need to know it lives in a browser, but your users want pretty urls and deep links.
 

 ◊section[#:headline "Wait, my application doesn't need to know it lives in a browser?"]{

 URLs are great for finding things on the internet.  But a single page application is not the same as a collection of
 resources that lives on a remote server.
 
 A single page application is a web application only in the sense that it lives on the web.  URLs are are not essential
 to it working well.
 
 URLs give users accessing your application in a browser the ability to bookmark a particular view in your application
 so that their expectation of browser-based applications will continue to work.
 
 We think that's a good thing, but we also don't think the idea of url paths should be littered through your application.
 
 When you are developing a redux application, you want your UI to be a pure function of the current state tree.
 
 By adding routes to that, it makes it harder to test.  And this difficulty can be compounded by other decisions about how
 to add routes to your application.

 }

 ◊section[#:headline "An alternative approach"]{
 React Router is the currently-accepted way to do URL routing in React
 applications.  For a standard React application without Redux, this
 solution isn't too bad.  But once you add Redux, things get difficult.
 
 We basically discovered the same lessons as Formidable Labs:◊sidenote["REACTROUTERWRONG"]{
 ◊a[#:href
 "http://formidable.com/blog/2016/07/11/let-the-url-do-the-talking-part-1-the-pain-of-react-router-in-redux/"]{React
 Router is the wrong way to route in Redux apps.}}  However, we don't
 think their solution (◊a[#:href
 "https://github.com/FormidableLabs/redux-little-router"]{redux-little-router})
 goes far enough, as it still embeds the idea of routes throughout your
 user interface.
 
 Once you separate URLs from your application state, you can easily
 port it to other environments that don't know what URLs are, and by
 simply removing the routing declaration, things will work as before.
 
 As an added (and we think absolutely essential) benefit, your entire
 application becomes easier to test, as rendering is a pure function of
 Redux state, and model logic and route actions are entirely
 encapsulated in Redux outside of the app.}
 
 ◊section[#:headline "Simple Routing in 25 lines"]{
 ◊pre{
 ◊code[#:class "javascript"]{

 import installBrowserRouter from 'routedux';
 import {createStore, compose, applyMiddleware} from 'redux';
 
 const LOAD_USER = 'LOAD_USER';
 
 function currentUserId() {
   return 42;
 };
 
 function reduce(state = initialState(), action) {
   ...
 }
 
 const routesConfig = [
   ['/user/:id', LOAD_USER, {}],
   ['/user/me', LOAD_USER, {id: currentUserId()}],
   ['/article/:slug', 'LOAD_ARTICLE', {}],
   ['/', 'LOAD_ARTICLE', {slug: "home-content"}]
 ];
 
 const {enhancer, middleware} = installBrowserRouter(routesConfig);
 
 const store = createStore(reduce, compose(
   enhance,
   applyMiddleware(middleware)
 ));

 }}

 
 Any time a handled action fires the url in the address bar will change, and if the url in the address bar changes
 the corresponding action will fire (unless the action was initiated by a url change).

 }

 ◊section[#:headline "Route matching precedence - which route matches best?"]{

 Route precedence is a function of the type of matching done in each segment and the order in which the wildcard segments
 match.  Exact matches are always preferred to wildcards moving from left to right.
 

 ◊pre{
 ◊code[#:class "javascript"]{

 const routesInOrderOfPrecedence = [
   ['/user/me/update', '/user/me'], // both perfectly specific - will match above any wildcard route
   '/user/me/:view',
   '/user/:id/update', // less specific because 'me' is exact match, while :id is a wildcard
   '/user/:id/:view'
 ];

 }}
 }

 ◊section[#:headline "Fragment component"]{
 ◊pre{
 ◊code[#:class "javascript"]{

 const state = {
   menu: ...
 }
 
 const view = (
   <PageFrame>
       <Fragment state={state} filterOn="menu">
         <Menu />
       </Fragment>
   </PageFrame>
 )
 
 // If menu is truthy, this renders as:
 (
   <PageFrame>
     <Menu />
   </PageFrame>
 )
 
 // If menu is falsy, this renders as:
 (
   <PageFrame>
   </PageFrame>
 )
 
 // If property is missing in path, it's falsy.
 const view = (
   <PageFrame>
       <Fragment state={state} filterOn="menu.missingProp.something">
         <Menu />
       </Fragment>
   </PageFrame>
 )
 
 // Renders as:
 (
   <PageFrame>
   </PageFrame>
 )

 }}

 
 Given that every UI state will be in your state tree as a function of your reducer logic, you can express any restriction
 on which parts of the UI display, even those that have nothing to do with the specific transformations caused by
 your URL actions.
 

 We have a demo codebase at ◊a[#:href "https://github.com/cjdev/routedux-docs-demo"]{demo repository}.

 }
 }