118 lines
3.0 KiB
JavaScript
118 lines
3.0 KiB
JavaScript
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'use strict';
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// This file just a dummy example of a HTTP API to talk to the backend.
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// The state of the "database" that would normally live on the server
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// is simply held here in memory.
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const backendStateForLoggedInPerson = {
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chats: [
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{
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name: 'Claire',
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messages: [
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{
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name: 'Claire',
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text: 'I ❤️ React Native!',
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},
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],
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},
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{
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name: 'John',
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messages: [
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{
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name: 'John',
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text: 'I ❤️ React Native!',
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},
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],
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}
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],
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};
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/**
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* Randomly simulate network failures.
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* It is useful to enable this during development to make sure our app works
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* in real-world conditions.
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*/
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function isNetworkFailure() {
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const chanceOfFailure = 0; // 0..1
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return Math.random() < chanceOfFailure;
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}
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/**
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* Helper for the other functions in this file.
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* Simulates a short delay and then returns a provided value or failure.
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* This is just a dummy example. Normally we'd make a HTTP request,
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* see http://facebook.github.io/react-native/docs/network.html
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*/
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function _makeSimulatedNetworkRequest(getValue) {
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const durationMs = 400;
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return new Promise(function (resolve, reject) {
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setTimeout(function () {
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if (isNetworkFailure()) {
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reject(new Error('Network failure'));
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} else {
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getValue(resolve, reject);
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}
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}, durationMs);
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});
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}
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/**
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* Fetch a list of all chats for the logged in person.
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*/
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async function fetchChatList() {
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return _makeSimulatedNetworkRequest((resolve, reject) => {
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resolve(backendStateForLoggedInPerson.chats.map(chat => chat.name));
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});
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}
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/**
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* Fetch a single chat.
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*/
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async function fetchChat(name) {
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return _makeSimulatedNetworkRequest((resolve, reject) => {
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resolve(
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backendStateForLoggedInPerson.chats.find(
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chat => chat.name === name
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)
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);
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});
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}
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/**
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* Send given message to given person.
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*/
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async function sendMessage({name, message}) {
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return _makeSimulatedNetworkRequest((resolve, reject) => {
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const chatForName = backendStateForLoggedInPerson.chats.find(
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chat => chat.name === name
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);
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if (chatForName) {
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chatForName.messages.push({
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name: 'Me',
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text: message,
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});
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resolve();
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} else {
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reject(new Error('Uknown person: ' + name));
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}
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});
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}
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const Backend = {
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fetchChatList,
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fetchChat,
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sendMessage,
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};
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export default Backend;
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// In case you are looking into using Redux for state management,
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// this is how network requests are done in the f8 app which uses Redux:
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// - To load some data, a Component fires a Redux action, such as loadSession()
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// - That action makes the HTTP requests and then dispatches a redux action
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// {type: 'LOADED_SESSIONS', results}
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// - Then all reducers get called and one of them updates a part of the application
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// state by storing the results
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// - Redux re-renders the connected Components
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// See https://github.com/fbsamples/f8app/search?utf8=%E2%9C%93&q=loaded_sessions
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