javascript - Javascript 如何正确获取嵌套对象
问题描述
我正在构建一个 Electron 应用程序,它从用户那里获取某种 json 文件并记录其中的所有数据。但是我收到关于从数量中获取未定义的错误:Json File:
{
"tiers": [
{
"trades": [
{
"wants": [
{
"item": "minecraft:string",
"quantity": {
"min": 15,
"max": 20
}
}
],
"gives": [
{
"item": "minecraft:emerald"
}
]
},
{
"wants": [
{
"item": "minecraft:emerald"
}
],
"gives": [
{
"item": "minecraft:arrow",
"quantity": {
"min": 8,
"max": 12
}
}
]
}
]
},
{
"trades": [
{
"wants": [
{
"item": "minecraft:gravel",
"quantity": 10
},
{
"item": "minecraft:emerald",
"quantity": 1
}
],
"gives": [
{
"item": "minecraft:flint",
"quantity": {
"min": 6,
"max": 10
}
}
]
},
{
"wants": [
{
"item": "minecraft:emerald",
"quantity": {
"min": 2,
"max": 3
}
}
],
"gives": [
{
"item": "minecraft:bow"
}
]
}
]
}
]
}
这是 main.js:
const { app, BrowserWindow, ipcMain, dialog, ipcRenderer, globalShortcut } = require('electron');
const { autoUpdater } = require('electron-updater');
const path = require('path');
const Store = require('./classes/Store.js');
const { electron } = require('process');
const { setTimeout } = require('timers');
// import Vue from 'vue';
// import Vuetify from 'vuetify';
// import "vuetify/dist/vuetify.min.css";
// Vue.use(Vuetify);
let win;
let loadingScreen;
const store = new Store({
configName: 'settings',
defaults: {
windowBounds: {
width: 800,
height: 600,
x: 0,
y: 0,
},
isMaximized: false,
fullscreen: false
}
});
function createLoadingScreen() {
loadingScreen = new BrowserWindow(Object.assign({
width: 200,
height: 220,
frame: false,
transparent: true,
icon: 'build/icons/icon.png',
webPreferences: {
worldSafeExecuteJavaScript: true
}
}));
loadingScreen.setResizable(false);
loadingScreen.loadURL('file://' + __dirname + '/extraWindows/loadingScreen/loading.html');
loadingScreen.setOverlayIcon('build/icons/icon.png', "Route");
loadingScreen.on('closed', () => loadingScreen = null);
loadingScreen.webContents.on('did-finish-load', () => {
loadingScreen.show();
});
}
function createWindow() {
let width = store.get('windowBounds.width');
let height = store.get('windowBounds.height');
let x = store.get('windowBounds.x');
let y = store.get('windowBounds.y');
let isMaximized = store.get('isMaximized');
win = new BrowserWindow({
width,
height,
x,
y,
icon: 'build/icons/icon.png',
frame: false,
titleBarStyle: "hidden",
webPreferences: {
enableRemoteModule: true,
nodeIntegration: true,
webSafeExecuteJavaScript: true
},
show: false
})
win.setOverlayIcon('build/icons/icon.png', "Route");
if(isMaximized == true) {
win.maximize();
}
win.loadFile('index.html');
win.on('closed', function() {
win = null;
settingScreen = null;
});
win.webContents.on('did-finish-load', () => {
if(loadingScreen) {
loadingScreen.close();
win.show();
}
})
win.on('resize', () => {
store.set('windowBounds', win.getBounds());
});
win.on('move', () => {
store.set('windowBounds', win.getBounds());
})
win.on('maximize', () => {
store.set('isMaximized', true);
})
win.on('unmaximize', () => {
store.set('isMaximized', false);
})
win.on('show', () => {
win.setFullScreen(store.get('fullscreen'));
})
win.once('ready-to-show', () => {
autoUpdater.checkForUpdatesAndNotify();
})
}
function createSettings() {
settingScreen = new BrowserWindow({
width: 600,
height: 800,
frame: false,
parent: win,
modal: true,
titleBarStyle: "hidden",
webPreferences: {
enableRemoteModule: true,
nodeIntegration: true,
worldSafeExecuteJavaScript: true
},
show: false
})
settingScreen.loadFile('extraWindows/settingsScreen/settings.html');
settingScreen.on('close', (event) => {
event.preventDefault();
settingScreen.hide();
})
}
app.on('ready', () => {
createLoadingScreen();
setTimeout(() => {
createWindow();
createSettings();
}, 5000); // Set to 5000
});
app.on('window-all-closed', () => {
if(process.platform !== 'darwin') {
app.quit()
}
})
app.on('activate', () => {
if(BrowserWindow.getAllWindows().length === 0) {
createWindow();
}
})
app.whenReady().then(() => {
globalShortcut.register('CmdOrCtrl+O', () => {
win.webContents.send('openFile');
})
globalShortcut.register('CmdOrCtrl+D', () => {
win.webContents.send('closeFile');
})
})
// These are all of the ipc functions needed for Route to work
ipcMain.handle('viewSettings', (event, arg) => {
if(arg === "true") {
settingScreen.show();
} else if(arg === "false") {
settingScreen.hide();
}
});
ipcMain.handle('changeSettings', (event, arg) => {
if(arg === "fullScreen") {
if(win.isFullScreen() == false) {
win.setFullScreen(true);
store.set('fullscreen', true);
} else {
win.setFullScreen(false);
store.set('fullscreen', false);
}
// Fill in the data for fullscreen
} else if(arg === 'themechooser') {
// Fill in the data for themes
}
});
ipcMain.on('appVersion', (event) => {
event.sender.send('appVersion', { version: app.getVersion() });
});
ipcMain.on('restartApp', () => {
autoUpdater.quitAndInstall();
})
autoUpdater.on('updateAvailable', () => {
win.webContents.send('updateAvailable');
});
autoUpdater.on('updateDownloaded', () => {
win.webContents.send('updateDownloaded');
})
这是 renderer.js:
const { app, ipcRenderer } = require('electron');
const Store = require('./classes/Store.js');
const remote = require('electron').remote;
const dialog = require('electron').remote.dialog;
const fs = require('fs');
const { S_IFDIR } = require('constants');
const { electron } = require('process');
const { version } = require('os');
let currentWindow = remote.getCurrentWindow();
let $ = function(selector) {
return document.querySelector(selector);
}
let projectArray = [];
// There can only be 5 projects max. Might add more.
let projectCount = 0;
document.querySelector('#tradeSetup').addEventListener('click', () => {
//Create a new setup.
alert("This works!");
});
let fileOpenerOptions = {
title: "Open Trade File",
defaultPath: "C:\\",
buttonLabel: "Start Coding",
properties: [ 'openFile' ],
filters: [
{ name: 'Json', extensions: ['json'] },
{ name: 'All FIles', extensions: ['*'] }
]
}
//Top bar buttons
function openFile() {
dialog.showOpenDialog(currentWindow, fileOpenerOptions).then(fileNames => {
if(fileNames == undefined || fileNames == null) {
console.log("No file selected.");
return;
} else {
let projectName = path.basename(fileNames.filePaths[0], path.extname(fileNames.filePaths[0]));
let rawFileData = fs.readFileSync(fileNames.filePaths[0]);
let fileData = JSON.parse(rawFileData);
console.log(fileData);
if(projectCount < 5) {
projectCount++;
createProject(projectName, fileData);
// Run code
} else if (projectCount == 5) {
alert('Support for more projects is not available yet!\nPlease wait until a later update to have more than 5 projects.');
}
}
});
}
function openSettings() {
ipcRenderer.invoke('viewSettings', "true");
}
function closeFile() {
if(document.querySelector('.activeProjectButton') == null) {
console.log("No project to close.");
} else {
let contine = confirm("Is this project the furthest project to the right? If not, please don't close it.\nThis is a bug that is being worked on.");
if(contine == true) {
document.querySelector('.activeProjectButton').remove();
document.querySelector('.activeWorkspace').remove();
projectCount--;
document.querySelectorAll('.inactiveProjectWorkspace').j--;
}
// Add a fun little secret for users
}
}
document.querySelector('#openFile').addEventListener('click', () => {
openFile();
});
document.querySelector('#openSettings').addEventListener('click', () => {
openSettings();
});
document.querySelector('#closeFile').addEventListener('click', () => {
closeFile();
})
// Create and switch projects
function createProject(name, projectData) {
// This is a beta feature for now. It is not finished
// Create the tab
let projectInProduction = document.createElement("button");
projectInProduction.id = "project" + projectCount + "Click";
projectInProduction.classList.add("invisButton");
projectInProduction.classList.add("inactiveProjectButton");
projectInProduction.classList.add("project" + projectCount);
projectInProduction.innerHTML += (name);
// Remove the welcome message
document.querySelector('.unHidden').classList.add('hidden');
document.querySelector('.unHidden').classList.remove('unHidden');
//Create the workspace
let workspaceInProduction = document.createElement("div");
workspaceInProduction.classList.add("inactiveWorkspace");
projectArray.push(projectData);
if(projectArray[projectCount - 1].tiers == null) {
alert("This is not a trade file!\nPlease use a trade file!");
} else {
$('.projects').appendChild(projectInProduction);
$('#jsonProjectContainer').appendChild(workspaceInProduction);
let table = document.createElement('table');
table.innerHTML += '<tr><th colspan="3">Buying</th><th colspan="2">Selling</th></tr>';
table.classList.add('table' + projectCount);
workspaceInProduction.appendChild(table);
let tiers = Object.keys(projectArray[projectCount - 1].tiers).length;
console.log(tiers);
for(let i = 0; i < tiers; i++) {
let tradesC = Object.keys(projectArray[projectCount - 1].tiers[i].trades).length;
for(let j = 0; j < tradesC; j++) {
let wants = Object.keys(projectArray[projectCount - 1].tiers[i].trades[j].wants);
let wantsC = Object.keys(projectArray[projectCount - 1].tiers[i].trades[j].wants).length;
let gives = Object.keys(projectArray[projectCount - 1].tiers[i].trades[j].gives);
for(let k = 0; k < wantsC; k++) {
let wantsItem = projectArray[projectCount - 1].tiers[i].trades[j].wants[k].item;
let wantsMin = projectArray[projectCount - 1].tiers[i].trades[j].wants[k].quantity["min"];
let wantsMax = projectArray[projectCount - 1].tiers[i].trades[j].wants[k].quantity["max"];
let givesItem = projectArray[projectCount - 1].tiers[i].trades[j].gives[0].item;
console.log("Wants: " + wants[k]);
console.log("Min: " + wantsMin);
console.log("Max: " + wantsMax);
console.log("Item: " + wantsItem);
console.log("Gives: " + gives);
console.log("Item: " + givesItem);
}
}
}
}
// Add a onlclick function to make switching projects work
j = projectCount;
document.getElementById('project' + projectCount + 'Click').addEventListener('click', function(j) {
let buttonIndex = j;
let buttonNodes = $('.projects').children;
let workspaceNodes = $('#jsonProjectContainer').children;
for(let i = 0; i < buttonNodes.length; i++) {
if(i == (j - 1)) {
buttonNodes[i].classList.add('activeProjectButton');
buttonNodes[i].classList.remove('inactiveProjectButton');
workspaceNodes[i].classList.add('activeWorkspace');
workspaceNodes[i].classList.remove('inactiveWorkspace');
} else {
buttonNodes[i].classList.remove('activeProjectButton');
buttonNodes[i].classList.add('inactiveProjectButton');
workspaceNodes[i].classList.remove('activeWorkspace');
workspaceNodes[i].classList.add('inactiveWorkspace');
}
}
}.bind(null, j));
}
// Title bar scripts
ipcRenderer.on('openFile', () => {
openFile();
})
ipcRenderer.on('closeFile', () => {
closeFile();
})
// App updates
ipcRenderer.send('appVersion');
ipcRenderer.on('appVersion', (event, arg) => {
ipcRenderer.removeAllListeners('appVersion');
//version.innerText = ;
});
const updateNotifier = document.getElementById('updateNotifier');
const updateAvailability = document.getElementById('updateAvailability');
const restartButton = document.getElementById('restartButton');
ipcRenderer.on('updateAvailable', () => {
ipcRenderer.removeAllListeners('updateAvailable');
updateAvailability.innerText = 'A new version of Route is available. Downloading now...';
updateNotifier.classList.remove('hidden');
});
ipcRenderer.on('update_downloaded', () => {
ipcRenderer.removeAllListeners('updateDownloaded');
updateAvailability.innerText = 'Update downloaded. It will be installed on restart. Restart to continue.';
restartButton.classList.remove('hidden');
updateNotifier.classList.remove('hidden');
});
function restartApp() {
ipcRenderer.send('restartApp');
}
这是 index.html:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>route - Minecraft Addon Tool</title>
<!-- https://electronjs.org/docs/tutorial/security#csp-meta-tag -->
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'unsafe-inline';" />
<link href="index.css" type="text/css" rel="stylesheet" />
<link href="node_modules/@mdi/font/css/materialdesignicons.min.css" type="text/css" rel="stylesheet" />
</head>
<body>
<script>
// const electron = require('electron').remote;
const path = require('path');
const customTitleBar = require('custom-electron-titlebar');
const Menu = require('electron').remote.Menu;
const MenuItem = require('electron').remote.MenuItem;
let mainTitlebar = new customTitleBar.Titlebar({
backgroundColor: customTitleBar.Color.fromHex('#391B47'),
icon: 'build/icons/icon.png'
});
const menu = new Menu();
menu.append(new MenuItem({
label: 'Github',
click: () => {
currentWindow.webContents.on('new-window', require('electron').shell.openExternal('https://github.com/Gekocaretaker/route'));
}
}));
menu.append(new MenuItem({
label: 'Discord',
click: () => {
console.log("Hiding the link!");
}
}));
menu.append(new MenuItem({
label: 'File',
submenu: [
{
label: 'Open File',
accelerator: 'Ctrl+O',
click: () => {
openFile();
}
},
{
label: 'Close File',
accelerator: 'Ctrl+D',
click: () => {
closeFile();
}
},
{
label: 'New File',
accelerator: 'Ctrl+N',
click: () => {
console.log("This is not yet available.");
}
}
]
}))
mainTitlebar.updateMenu(menu);
</script>
<div class="grid-container">
<div class="buttons">
<div class="tooltip openFileContainer">
<button id="openFile" class="invisButton"><span class="mdi mdi-file mdi-48px"></span></button>
<div>File</div>
</div>
<div class="tooltip settingsContainer">
<button id="openSettings" class="invisButton"><span class="mdi mdi-cog-outline mdi-48px"></span></button>
<div>Settings</div>
</div>
<div class="tooltip closeProjectContainer">
<button id="closeFile" class="invisButton"><span class="mdi mdi-close mdi-48px"></span></button>
<div>Close Project</div>
</div>
</div>
<div class="projects">
<!-- <div class="project1">
<button class="invisButton activeProjectButton" id="project1Click">Project 1</button>
</div> -->
</div>
<div class="jsonEditor">
<!-- <div class="workSpace1 activeWorkSpace">
<h3>This is Workspace 1</h3>
</div> -->
<div id="jsonProjectContainer"></div>
<div class="unHidden">
<p id="welcomeMessage">Hello User! Welcome to Route. I hope you enjoy using this!</p>
</div>
<div id="updateNotifier" class="hidden">
<p id="updateAvailability"></p>
<button id="restartButton" onclick="restartApp()"></button>
</div>
</div>
<div class="sidebar">
<div class="tooltip tradeBuilder">
<button id="tradeSetup" class="invisButton"><span class="mdi mdi-apache-kafka mdi-48px"></span></button>
<div>Basic Trade</div>
</div>
<div class="tooltip whatNext">
<button id="whatsNext" class="invisButton"><span class="mdi mdi-help mdi-48px"></span></button>
<div>Whats Next?</div>
</div>
</div>
</div>
<script src="renderer.js"></script>
</body>
</html>
这是错误:
Uncaught (in promise) TypeError: Cannot read property 'min' of undefined at createProject (renderer.js:126) at renderer.js:48
而且我很确定错误来自我如何获得“min”。我尝试过使用 ["min"]、['min']、.min,并且作为最后的手段,使用 [0]。
如果需要共享,我将代码托管在 github 上。
解决方案
如果您要调试代码,您会注意到当 j=1 和 k=0 时会发生错误。然后,如果您检查对象,您会注意到在该位置没有question
属性:
{
"tiers": [
{
"trades": [
{
/* ... */
},
{
"wants": [
{
"item": "minecraft:emerald"
/* no quantity here */
}
],
"gives": [
/* ... */
]
}
]
},
/* ... */
因此,您必须决定在没有quantity
财产时要发生什么。例如,您可以使用可选的链接运算符来使用默认值:
let wantsMin = projectArray[projectCount - 1].tiers[i].trades[j].wants[k].quantity.?min || 0;
let wantsMax = projectArray[projectCount - 1].tiers[i].trades[j].wants[k].quantity.?max || 0;
以上将给出 0 作为缺少的最小/最大值的值。但这一切都取决于您希望在这种情况下发生什么。
这只是一个关于如何规避错误的示例,但根据您的其余代码,可能不是处理它的正确方法。这由你来决定。
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