How to implement Flux / Redux Action authorization or availability - javascript

The Requirement
We are currently building a client App that is supposed to work with a HATEOAS REST-API. This means the API itself tells us which further actions are currently available - comparable with an authorization.
For example:
We have an entity Projects and a Component ProjectWidget which is basically a paginated List of Projects. The Server API gives us the first 10 Projects by default and - depending if there are more - integrates an URL to the next 10 Projects. The JSON-Reponse for a Page 2 of such a list would look like this:
{
"_embedded" : [ ... ], // list of project-entities
"_links" : {
"prev" : "myApi.com/projects?page=1"
"self" : "myApi.com/projects?page=2"
"next" : "myApi.com/projects?page=3"
}
}
On page 1, the links section is simply missing the prev property as there is no previous page. In my component, I want to show a Previous and Next Button depending if those properties are available in the response or not.
Conclusion: My App doesnt know which actions are available and when they are. This means that the currently available actions also belong to the state of the current app as well as the data itself.
Build it with Flux/Redux
Now I want to somehow put this into a flux architecture using for example redux (the concrete implementation doesnt really matter at this point).
Of course, the asynchronous calls to my server-api need to go into an ActionCreator which then has two tasks when the server responds:
Dispatch Action to put the data itself into the store
Dispatch Action to put the next available actions (or at least the information on how to create them) into the store
The model could look like this:
{
projects: {
data: [...], // the list of my projects
actions: {
previous: 'myApi.com/projects?page=1' // Prepared action to load the previous 10
next: 'myApi.com/projects?page=3' // Prepared action to load the next 10 Projects
}
}
}
Then the ActionCreator would need to look like this:
export loadProjectsFrom(href){
return () => {
myApi
.get(href)
.subscribe((response) => {
store.dispatch({type: 'LOADED_PROJECTS', payload: response._embedded})
store.dispatch({
type: 'LOADED_PROJECTS_ACTIONS',
payload: {next: response._links.next, prev: reponse._links.prev})
});
}
}
A ViewComponent could then easily subscribe to both - the actions and the projects and create new actions from the information provieded in the store:
let state = store.getState();
if(state.projects.actions.next){
// Render the button with onclick event calling the function below
}
onClick() {
let href = store.getState().projects.actions.next;
let loadAction = actionCreator.loadProjectsFrom(href);
store.dispatch(loadAction);
}
My Questions
Is my conclusion even correct that the available actions are part of the state?
Is it a good pattern to create actions from information directly taken from the store? (it seems like it introduces a tight coupling between the two)
Are there any alternatives on how to implement this sort of Actionauthorization or -availability?

Related

Service Worker determine number of clients

We've got a SaaS app that's PWA capable and we're using Workbox for the grunt work. Up to now we've been following the tried and trusted recipe of displaying an update is available banner to the users, prompting them to update their web app.
Viewing usage data (via Sentry.io) we've noticed that most users simply seem to ignore the update banner and continue with the version they're on.
So we're looking at trying something different. This is to perform the update automatically when they change the route in the web app (when we know there's an update available).
Testing this shows that it does work. However there's a side-effect, and that is if they've got web app open in multiple tabs, then all the tabs get updated. This could be problematic for users' if they've got an un-saved form open in one of the tabs in the background - they'll potentially loose their work.
This happens during this piece of code:
// app shell page, created lifecycle hook
document.addEventListener('swUpdated', this.SetPwaRegistration, { once: true })
navigator.serviceWorker.addEventListener('controllerchange', () => {
if (this.refreshing) {
return
}
this.refreshing = true
window.location.reload()
})
// app shell page, method in methods collection
SetPwaRegistration (event) {
// call mutation to pass the registration object to Vuex
this.PWA_REGISTRATION_SET({ pwaRegistration: event.detail })
}
// main.js
router.afterEach((to, from) => {
// retrieve the registration object from Vuex
const pwaRegistration = app.$store.getters.pwaRegistration
if (pwaRegistration) {
pwaRegistration.waiting.postMessage('skipWaiting')
}
})
the above code is from our Vue.js app code-base, the this.refreshing is set to false by default in the data property collection.
What I'd like to know if whether it is possible to determine if the Service Worker has only one client under it's control (i.e. the web app is only open in 1 browser tab), and if this is the case, the auto-update can happen without potential issues. If there's more than one client, then we'll display the update banner as usual.
As a brief update to this, I've come across code examples similar to this:
self.clients.matchAll().then(clients => {
const clientCount = clients.length
// store count of client in Vuex
})
Which looks like an option (i.e. count how many clients there are, store this in Vuex store), I'm just not sure where it should be used.
If you want to orchestrate the reload from entirely within the service worker, you can effectively do that by using the WindowClient interface to programmatically navigate to whatever the current URL is, which is roughly equivalent to a reload.
The two things to keep in in mind that navigate() will only work on WindowClients (not Workers) and that you can only call it if the service worker controls the WindowClient.
Putting that together, here's something to try:
// This can be run, e.g., in a `message` handler in your SW:
self.clients.matchAll({
// These options are actually the defaults, but just
// to be explicit:
includeUncontrolled: false,
type: 'window',
}).then((clients) => {
if (clients.length === 1) {
clients[0].navigate(clients[0].url);
}
})

React - controlling async calls smartly without any side effect in complex applications

Solution proposed by codeslayer1 in question raised at React - Controlling multiple Ajax Calls has an issue of accessing state directly inside action creator - an anti pattern.
So, if I don't access the state inside my action creator what I will do is, I will listen to a batchRequestCompleted state in my component. When components prop batchRequestCompleted will become true(means previous request is completed), I will check if any pending requests are there. If yes, I will dispatch action to process those next requests. So basically saga calls action which in turn modifies the state. And once state is modified, another action to process further requests is dispatched from component. In this way, saga never accesses the state.
Solution above sounds good but comes at a cost of problem mentioned in Route change before action creator completes. That is, what will happen to the requests placed inside queue if someone navigates to a different route, before queue is cleared.
Can I solve the problem mentioned in React - Controlling multiple Ajax Calls without accessing state inside action creators and without bringing component back in picture for dispatching an action to clear the pending queue.
Note: I have created a new question because problem mentioned in React - Controlling multiple Ajax Calls is solved but with side effects and this question majorly focuses on reaching to a solution which cleans off that side effect.
I made a little repo github.com/adz5a/so-stream-example to illustrate how I would solve your problem.
This repo uses two libraries xstream and recompose. The former provides an implementation of ObservableStreams with its operators and the latter wires it up with React.
A concept is necessary before everything : ES Observables. They are covered in depth in articles such as this (I strongly recommend reading and listening to past articles / talks from Ben Lesh, on this subject).
Observabes are a lazy primitive used to model values over time. In JS we have another primitive for doing async : Promises. Those models an eventual value or error and thus are not lazy but eager. In the case of a React component ( or more generally UI ) we are interested in lazyness because things can go wrong : the user may want to interrupt a long running process, it can crash, change route etc...
So, how can we solve your problem : controlling a long running process which can be interrupted ( fetching lots of rows ) by user interaction ?
First, the UI :
export class AnswerView extends React.Component {
static propTypes = {
// called when the user make a batch
// of request
onStart: PropTypes.func.isRequired,
// called when you want to stop the processing
// of requests ( when unmounting or at the request
// of the user )
onStop: PropTypes.func.isRequired,
// number of requests completed, 0 by default
completedRequests: PropTypes.number.isRequired,
// whether it's working right now or not
processing: PropTypes.bool.isRequired
};
render () {
// displays a form if no work is being done,
// else the number of completed requests
return (
<section>
<Link to="/other">Change Route !</Link>
<header>
Lazy Component Example
</header>
{
this.props.processing ?
<span>{"requests done " + this.props.completedRequests}<button onClick={this.props.onStop}>Stop !</button></span>:
<form onSubmit={e => {
e.preventDefault();
this.props.onStart(parseInt(e.currentTarget.elements.number.value, 10));
}}>
Nb of posts to fetch<input type="number" name="number" placeholder="0"/>
<input type="submit" value="go"/>
</form>
}
</section>
);
}
componentWillMount () {
console.log("mounting");
}
}
Pretty simple : a form with an input for the number of requests to perform (could checkboxes on a table component ... ).
Its props are as follow :
onStart : fn which takes the desired number
onStop : fn which takes no args and signals we would like to stop. Can be hooked to a button or in this case, componentWillUnmout.
completedRequests: Integer, counts requests done, 0.
processing: boolean, indicates if work is under way.
This does not do much by itself, so let's introduce recompose. Its purpose is to enhance component via HOC. We will use the mapPropsStream helper in this example.
Note : in this answer I use stream / Observable interchangeably but this is not true in the general case. A stream is an Observable with operators allowing to transform the emitted value into a new Observable.
For a React Component we can sort of observe its props with the standard api : 1st one at componentWillMount, then at componentWillReceiveProps. We can also signal when there will be no more props with componentWillUnmount. We can build the following (marble) diagram : p1--p2--..--pn--| (the pipe indicates the completion of the stream).
The enhancer code is posted below with comments.
What needs to be understood is that everything with streams can be approached like a signal : by modelling everything as a stream we can be sure that by sending the appropriate signal we can have the desired behaviour.
export const enhance = mapPropsStream(prop$ => {
/*
* createEventHandler will help us generates the callbacks and their
* corresponding streams.
* Each callback invocation will dispatch a value to their corresponding
* stream.
*/
// models the requested number of requests
const { handler: onStart, stream: requestCount$ } = createEventHandler();
// models the *stop* signals
const { handler: onStop, stream: stop$ } = createEventHandler();
// models the number of completed requests
const completedRequestCount$ = requestCount$.map( n => {
// for each request, generate a dummy url list
const urls = Array.from({ length: n }, (_, i) => `https://jsonplaceholder.typicode.com/posts/${i + 1}` );
// this is the trick : we want the process to be aware of itself when
// doing the next operation. This is a circular invocation so we need to
// use a *proxy*. Note : another way is to use a *subject* but they are
// not present in __xstream__, plz look at RxJS for a *subject* overview
// and implementation.
const requestProxy$ = xs.create();
const count$ = requestProxy$
// a *reduce* operation to follow where we are
// it acts like a cursor.
.fold(( n ) => n + 5, 0 )
// this will log the current value
.debug("nb");
const request$ = count$.map( n => Promise.all(urls.slice(n, n + 5).map(u => fetch(u))) )
.map(xs.fromPromise)
.flatten()
.endWhen(xs.merge(
// this stream completes when the stop$ emits
// it also completes when the count is above the urls array length
// and when the prop$ has emitted its last value ( when unmounting )
stop$,
count$.filter(n => n >= urls.length),
prop$.last()
));
// this effectively activates the proxy
requestProxy$.imitate(request$);
return count$;
} )
.flatten();
// models the processing props,
// will emit 2 values : false immediately,
// true when the process starts.
const processing$ = requestCount$.take(1)
.mapTo(true)
.startWith(false);
// combines each streams to generate the props
return xs.combine(
// original props
prop$,
// completed requests, 0 at start
completedRequestCount$.startWith(0),
// boolean indicating if processing is en route
processing$
)
.map(([ props, completedRequests, processing ]) => {
return {
...props,
completedRequests,
processing,
onStart,
onStop
};
})
// allows us to catch any error generated in the streams
// very much equivalent to the new ErrorBoundaries in React
.replaceError( e => {
// logs and return an empty stream which will never emit,
// effectively blocking the component
console.error(e);
return xs.empty();
} );
});
export const Answer = enhance(AnswerView);
I hope this answer is not (too) convoluted, feel free to ask any question.
As a side note, after a little research you may notice that the processing boolean is not really used in the logic but is merely there to help the UI know what's going on : this is a lot cleaner than having some piece of state attached to the this of a Component.

Replacing entire tree item in Redux with different reducer

Given the following redux state tree:
{
app: {...},
config: {...},
page_data: {...}
}
How would I replace the contents of page_data with an entire separate reducer depending on the page a user is on?
For example I could have three reducers user, products, competitions. If I switched from a user page to a product page I'd want the page_data branch to show:
{
page_data: {
productPage: {...}
}
}
with no reference to user as I don't want to bloat the app state and also don't need that data on the product page.
Note: I'm using combineReducers for reference.
Is this possible and what is the best approach?
Using same name for multiple reducers is definitely wrong. Not just it isn't supported, it's wrong practice. You can achieve this using FLUSH_PAGE_DATA action. Dispatching this action will flush the page data in all the reducers. It'll Look something like this.
case 'FLUSH_PAGE_DATA':
return { };
Then based on you active page, which you'll pass in every action, you can create different structure of page data.

How to show a loading indicator in React Redux app while fetching the data? [closed]

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I'm new to React/Redux. I use a fetch api middleware in Redux app to process the APIs. It's (redux-api-middleware). I think it's the good way to process async api actions. But I find some cases which can't be resolve by myself.
As the homepage (Lifecycle) say, a fetch API lifecycle begins with dispatching a CALL_API action ends with dispatching a FSA action.
So my first case is showing/hiding a preloader when fetching APIs. The middleware will dispatch a FSA action at the beginning and dispatch a FSA action at the end. Both the actions are received by reducers which should be only doing some normal data processing. No UI operations, no more operations. Maybe I should save the processing status in state then render them when store updating.
But how to do this? A react component flow over the whole page? what happen with store updating from other actions? I mean they are more like events than state!
Even a worse case, what should I do when I have to use the native confirm dialog or alert dialog in redux/react apps? Where should they be put, actions or reducers?
Best wishes! Wish for replying.
I mean they are more like events than state!
I would not say so. I think loading indicators are a great case of UI that is easily described as a function of state: in this case, of a boolean variable. While this answer is correct, I would like to provide some code to go along with it.
In the async example in Redux repo, reducer updates a field called isFetching:
case REQUEST_POSTS:
return Object.assign({}, state, {
isFetching: true,
didInvalidate: false
})
case RECEIVE_POSTS:
return Object.assign({}, state, {
isFetching: false,
didInvalidate: false,
items: action.posts,
lastUpdated: action.receivedAt
The component uses connect() from React Redux to subscribe to the store’s state and returns isFetching as part of the mapStateToProps() return value so it is available in the connected component’s props:
function mapStateToProps(state) {
const { selectedReddit, postsByReddit } = state
const {
isFetching,
lastUpdated,
items: posts
} = postsByReddit[selectedReddit] || {
isFetching: true,
items: []
}
return {
selectedReddit,
posts,
isFetching,
lastUpdated
}
}
Finally, the component uses isFetching prop in the render() function to render a “Loading...” label (which could conceivably be a spinner instead):
{isEmpty
? (isFetching ? <h2>Loading...</h2> : <h2>Empty.</h2>)
: <div style={{ opacity: isFetching ? 0.5 : 1 }}>
<Posts posts={posts} />
</div>
}
Even a worse case, what should I do when I have to use the native confirm dialog or alert dialog in redux/react apps? Where should they be put, actions or reducers?
Any side effects (and showing a dialog is most certainly a side effect) do not belong in reducers. Think of reducers as passive “builders of state”. They don’t really “do” things.
If you wish to show an alert, either do this from a component before dispatching an action, or do this from an action creator. By the time an action is dispatched, it is too late to perform side effects in response to it.
For every rule, there is an exception. Sometimes your side effect logic is so complicated you actually want to couple them either to specific action types or to specific reducers. In this case check out advanced projects like Redux Saga and Redux Loop. Only do this when you are comfortable with vanilla Redux and have a real problem of scattered side effects you’d like to make more manageable.
Great answer Dan Abramov!
Just want to add that I was doing more or less exactly that in one of my apps (keeping isFetching as a boolean) and ended up having to make it an integer (which ends up reading as the number of outstanding requests) to support multiple simultaneous requests.
with boolean:
request 1 starts -> spinner on -> request 2 starts -> request 1 ends -> spinner off -> request 2 ends
with integer:
request 1 starts -> spinner on -> request 2 starts -> request 1 ends -> request 2 ends -> spinner off
case REQUEST_POSTS:
return Object.assign({}, state, {
isFetching: state.isFetching + 1,
didInvalidate: false
})
case RECEIVE_POSTS:
return Object.assign({}, state, {
isFetching: state.isFetching - 1,
didInvalidate: false,
items: action.posts,
lastUpdated: action.receivedAt
I'd like to add something. The real world example uses a field isFetching in the store to represent when a collection of items is being fetched. Any collection is generalized to a pagination reducer that can be connected to your components to track the state and show if a collection is loading.
It happened to me that I wanted to fetch details for an specific entity that doesn't fit in the pagination pattern. I wanted to have a state representing if the details are being fetched from the server but also I didn't want to have a reducer just for that.
To solve this I added another generic reducer called fetching. It works in a similar fashion to the pagination reducer and it's responsibility is just to watch a set of actions and generate new state with pairs [entity, isFetching]. That allows to connect the reducer to any component and to know if the app is currently fetching data not just for a collection but for an specific entity.
I didn't happen upon this question until now, but since no answer is accepted I'll throw in my hat. I wrote a tool for this very job: react-loader-factory. It's got slightly more going on than Abramov's solution, but is more modular and convenient, since I didn't want to have to think after I wrote it.
There are four big pieces:
Factory pattern: This allows you to quickly call the same function to set up which states mean "Loading" for your component, and which actions to dispatch. (This assumes that the component is responsible for starting the actions it waits on.) const loaderWrapper = loaderFactory(actionsList, monitoredStates);
Wrapper: The component the Factory produces is a "higher order component" (like what connect() returns in Redux), so that you can just bolt it onto your existing stuff. const LoadingChild = loaderWrapper(ChildComponent);
Action/Reducer interaction: The wrapper checks to see if a reducer it's plugged into contains keywords that tell it not to pass through to the component that needs data. The actions dispatched by the wrapper are expected to produce the associated keywords (the way redux-api-middleware dispatches ACTION_SUCCESS and ACTION_REQUEST, for example). (You could dispatch actions elsewhere and just monitor from the wrapper if you wanted, of course.)
Throbber: The component you want to appear while the data your component depends on isn't ready. I added a little div in there so you can test it out without having to rig it up.
The module itself is independent of redux-api-middleware, but that's what I use it with, so here's some sample code from the README:
A component with a Loader wrapping it:
import React from 'react';
import { myAsyncAction } from '../actions';
import loaderFactory from 'react-loader-factory';
import ChildComponent from './ChildComponent';
const actionsList = [myAsyncAction()];
const monitoredStates = ['ASYNC_REQUEST'];
const loaderWrapper = loaderFactory(actionsList, monitoredStates);
const LoadingChild = loaderWrapper(ChildComponent);
const containingComponent = props => {
// Do whatever you need to do with your usual containing component
const childProps = { someProps: 'props' };
return <LoadingChild { ...childProps } />;
}
A reducer for the Loader to monitor (although you can wire it differently if you want):
export function activeRequests(state = [], action) {
const newState = state.slice();
// regex that tests for an API action string ending with _REQUEST
const reqReg = new RegExp(/^[A-Z]+\_REQUEST$/g);
// regex that tests for a API action string ending with _SUCCESS
const sucReg = new RegExp(/^[A-Z]+\_SUCCESS$/g);
// if a _REQUEST comes in, add it to the activeRequests list
if (reqReg.test(action.type)) {
newState.push(action.type);
}
// if a _SUCCESS comes in, delete its corresponding _REQUEST
if (sucReg.test(action.type)) {
const reqType = action.type.split('_')[0].concat('_REQUEST');
const deleteInd = state.indexOf(reqType);
if (deleteInd !== -1) {
newState.splice(deleteInd, 1);
}
}
return newState;
}
I expect in the near future I'll add things like timeout and error to the module, but the pattern's not going to be very different.
The short answer to your question is:
Tie rendering to rendering code--use a wrapper around the component you need to render with the data like the one I showed above.
Add a reducer that makes the status of requests around the app you might care about easily digestible, so you don't have to think too hard about what is happening.
Events and state aren't really different.
The rest of your intuitions seem correct to me.
Am I the only one thinking that loading indicators don't belong in a Redux store? I mean, I don't think it's part of an application's state per se..
Now, I work with Angular2, and what I do is that I have a "Loading" service which exposes different loading indicators via RxJS BehaviourSubjects.. I guess the mechanism is the same, I just don't store the information in Redux.
Users of the LoadingService just subscribe to those events they want to listen to..
My Redux action creators call the LoadingService whenever things need to change. UX components subscribe to the exposed observables...
You can add change listeners to your stores, using either connect() from React Redux or the low-level store.subscribe() method. You should have the loading indicator in your store, which the store change handler can then check and update the component state. The component then renders the preloader if needed, based on the state.
alert and confirm shouldn't be a problem. They are blocking and alert doesn't even take any input from the user. With confirm, you can set state based on what the user has clicked if the user choice should affect component rendering. If not, you can store the choice as component member variable for later use.
We have three types of notifications in our app, all of which are designed as aspects:
Loading indicator (modal or non-modal based on prop)
Error Popup (modal)
Notification snackbar (non-modal, self closing)
All three of these are at the top level of our app (Main), and wired through Redux as shown in the below code snippet. These props control display of their corresponding aspects.
I designed a proxy that handles all our API calls, thus all isFetching and (api) errors are mediated with actionCreators I import in the proxy. (As an aside, I also use webpack to inject a mock of the backing service for dev so we can work without server dependencies.)
Any other place in the app that needs to provide any type of notification simply imports the appropriate action. Snackbar & Error have params for messages to be displayed.
#connect(
// map state to props
state => ({
isFetching :state.main.get('isFetching'), // ProgressIndicator
notification :state.main.get('notification'), // Snackbar
error :state.main.get('error') // ErrorPopup
}),
// mapDispatchToProps
(dispatch) => { return {
actions: bindActionCreators(actionCreators, dispatch)
}}
)
export default class Main extends React.Component{
I'm saving the urls such as::
isFetching: {
/api/posts/1: true,
api/posts/3: false,
api/search?q=322: true,
}
And then I have a memorised selector (via reselect).
const getIsFetching = createSelector(
state => state.isFetching,
items => items => Object.keys(items).filter(item => items[item] === true).length > 0 ? true : false
);
To make the url unique in case of POST, I pass some variable as query.
And where I want to show an indicator, I simply use the getFetchCount variable

What is the right/preferred way to make a "Edit Detail" component in React?

I'm working on a page whose 'Data Model' is a collection, for example, an array of people. They are packed into React Components and tiled on the page. Essentially it's like:
class App extends React.Component {
constructor() {
super();
this.state = { people: /* some data */ };
}
render () {
return (
<div>
{this.state.people.map((person) =>
<People data={person}></People>)}
</div>);
}
}
Now I want to attach an edit section for each entry in <People> component, which allows the user to update the name, age ... all kinds of information for a specific entry.
Since React does not support mutating props inside components, I searched and found that adding callbacks as props can solve the problem of passing data to parent. But since there are many fields to update, there would be many callbacks such as onNameChanged, onEmailChanged... which could be very ugly (also more and more verbose as the number of fields keeps growing).
So what is the right way for it?
Honestly? The best way is Flux (back to that in a minute).
If you start to get into the process of passing data down the tree in the form of props, then passing it back up to be edited using callbacks, then you're breaking the unidirectional data flow that React is built around.
However, not all projects need to be written to ideal standards and it is possible to build this without Flux (and sometimes it might even be the right solution).
Without Flux
You can implement this without the need for a mass of callbacks, by passing down a single edit function as a prop. This function should take an id and a new person object, then update the state inside the parent component whenever it runs. Here's an example.
editPerson(id, editedPerson) {
const people = this.state.people;
const newFragment = { [id]: editedPerson };
// create a new list of people, with the updated person in
this.setState({
people: Object.assign([], people, newFragment)
});
},
render() {
// ...
{this.state.people.map((person, index) => {
const edit = this.editPerson.bind(this, index);
return (
<People data={person} edit={edit}></People>
);
})}
// ...
}
Then inside your person component, any time you make a change to the person, simply pass the person back up to the parent state with the callback.
However, if you visualize the flow of data through your application, you've now created a cycle that looks something like this.
App
^
|
v
Person
It's no longer trivial to work out where the data in app came from (it is still quite simple in such a small app, but obviously the bigger it gets the harder it is to tell.
With Flux
In the beginning, Facebook developers wrote React applications with unidirectional data flows and they saw that it was good. However, a need arose for data to go up the tree, which resulted in a crisis. How shall our data flow be unidirectional and still return to the top of the tree? And on the seventh day, they created Flux(1) and saw that it was very good.
Flux allows you to describe your changes as actions and pass them out of your components, to stores (self contained state boxes) which understand how to manipulate their state based on the action. Then the store tells all the components that care about it that something has changed, at which point the components can fetch new data to render.
You regain your unidirectional data flow, with an architecture that looks like this.
App <---- [Stores]
| ^
v |
Person --> Dispatcher
Stores
Rather than keeping your state in your <App /> component, you would probably want to create a People store to keep track of your list of people.
Maybe it would look something like this.
// stores/people-store.js
const people = [];
export function getPeople() {
return people;
}
function editPerson(id, person) {
// ...
}
function addPerson(person) {
// ...
}
function removePerson(id) {
// ...
}
Now, we could export these functions and let our components call them directly, but that's bad because it means that our components have to have knowledge of the design of the store and we want to keep them as dumb as possible.
Actions
Instead, our components create simple, serializable actions that our stores can understand. Here are some examples:
// remove person with id 53
{ type: 'PEOPLE_REMOVE', payload: 53 }
// create a new person called John Foo
{ type: 'PEOPLE_ADD', payload: { name: 'John Foo' } }
// edit person 13
{
type: 'PEOPLE_EDIT',
payload: {
id: 13,
person: { name: 'Unlucky Bill' }
}
}
These actions don't have to have these specific keys, they don't even have to be objects either, this is just the convention from Flux Standard Actions.
Dispatcher
Now, we have tell our store how to deal with these actions when they arrive.
// stores/people-store.js
// ...
dispatcher.register(function(action) {
switch(action.type) {
case 'PEOPLE_REMOVE':
removePerson(action.payload);
case 'PEOPLE_ADD':
addPerson(action.payload);
case 'PEOPLE_EDIT':
editPerson(action.payload.id, action.payload.person);
}
});
Phew. Lot of work so far, nearly there.
Now we can start to dispatch these actions from our components.
// components/people.js
// ...
onEdit(editedPerson) {
dispatcher.dispatch({
type: 'PEOPLE_EDIT',
payload: {
id: this.props.id,
person: editedPerson
}
});
}
onRemove() {
dispatcher.dispatch({
type: 'PEOPLE_REMOVE',
payload: this.props.id
});
}
// ...
When you edit the person, call the this.onEdit method and it will dispatch the appropriate action to your stores. Same goes for removing a person. Normally you'd move this stuff into action creators, but that's a topic for another time.
Ok, finally getting somewhere! Now our components can create actions that update the data in our stores. How do we get that data back into our components?
Initially, it's very simple. We can require the store in our top level component and simply ask for the data.
// components/app.js
import { getPeople } from './stores/people-store';
// ...
constructor() {
super();
this.state = { people: getPeople() };
}
We can pass this data down in exactly the same way, but what happens when the data changes?
The official stance from Flux is basically "Not our problem". Their examples use Node's Event Emitter class to allow stores to accept callback functions that are called when the store updates.
This allows you to write code that looks something like this:
componentWillMount() {
peopleStore.addListener(this.peopleUpdated);
},
componentWillUnmount() {
peopleStore.removeListener(this.peopleUpdated);
},
peopleUpdated() {
this.setState({ people: getPeople() });
}
Really, the ball is in your court on this one. There are many other strategies for getting the data back into your program. Reflux creates the listen method for you automatically, Redux allows you to declaratively specify which components receive which parts of the store as props, then it handles the updating. Spend enough time with Flux and you'll find a preference.
Now, you're probably thinking, blimey — this seems like a lot of effort to go to just to add edit functionality to a component; and you're right, it is!
For small applications, you probably don't need Flux.
Sure there are lots of benefits, but the additional complexity just isn't always warranted. As your application grows, you'll find that if you've fluxed it up, it will be much easier to manage, maintain and debug.
The trick is to know when it's appropriate to use the Flux architecture and hopefully when the time comes, this overly long, rambling answer will have cleared things up for you.
This isn't actually true.

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