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[英]Can I run my Node.js/Express backend and React.js frontend together in the same file structure?
[英]How can I update the frontend after waiting for the database in the backend to update in Node.js/Express?
我在此处看到类似的问题,但他们使用的是 MEAN-Stack。
我目前只是使用 'setTimeout' function 等待几秒钟,然后使用提取 api 从服务器请求新数据,让它有时间更新,但这感觉不是正确的方法。 有没有一种简单的方法让前端只在Express中更新数据库后才更新? 我是 Node 的新手,请原谅我。
应用程序.js:
const express = require('express');
const app = express();
const mysql = require('mysql');
let viewData = {
//html data
}
var pool = mysql.createPool({
connectionLimit : 10,
host: "localhost",
port: 3306,
database: 'testing',
user: "root",
password: "pass"
});
function sql(type) {
if(type == 'select') {
//Select query here
}
if(request == 'addRow') {
//Insert query here
}
}
app.get(`/`, function (req, res) {
res.sendFile('./views/index.html', {root: __dirname});
})
app.post('/api/add', function(req, res){
res.setHeader('Content-Type', 'application/json');
sql('addRow')
});
app.get('/api/viewData', function (req, res) {
res.setHeader('Content-Type', 'application/json');
res.send(JSON.stringify(viewData));
})
索引.js:
function loadData() {
fetch('/api/viewData')
.then(z => z.json())
.then(a => {
//update html
})
}
function postData(a) {
fetch('/api/add', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify({
//data to send to app.js
})
}).then(setTimeout(function(){loadData();}, 3000))
}
您应该使用异步并等待 function
示例:在异步/等待之后
async function fun1(req, res){
let response = await request.get('http://localhost:3000');
if (response.err) { console.log('error');}
else { console.log('fetched response');
}
我们示例的完整代码如下所示:
npm 安装 express jsonschema body-parser promise-mysql
var express = require('express');
var bodyParser = require('body-parser')
var app = express();
var validate = require('./validate')
var mysqlConnection = require('./connectionShare');
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
const addItem = function(item, connection){
console.log("Adding Item");
return new Promise(function(resolve, reject){
connection.query("INSERT INTO product SET ?", item)
.then(function(result){
resolve(item.seller);
}).catch(function(error){
reject(error);
});
})
}
const findOrCreateUser = function(user,connection){
console.log("Finding User");
return new Promise(function(resolve,reject){
connection.query("SELECT * FROM user WHERE email=" + connection.escape(user.email))
.then(function(results){
if(results.length == 1){
resolve(results[0].id)
} else {
connection.query("INSERT INTO user SET ?", user)
.then(function(results){
resolve(results.insertId);
});
}
}).catch(function(error){
reject(error);
})
})
}
const selectUserItems = function(userID,connection){
console.log("Selecting Items " + userID);
return new Promise(function(resolve,reject){
connection.query("SELECT * FROM product WHERE seller = " + connection.escape(userID))
.then(function(results){
resolve(results);
}).catch(function(error){
reject(error);return;
});
})
}
app.post('/add/product', validate.JsonValidation, mysqlConnection.getConnection, async function(req,res){
var connection = req.connection;
var item = {
name: req.body.name,
price: req.body.price,
width: req.body.width,
height: req.body.height,
added: req.body.added,
image: req.body.image
};
var user = {
username: req.body.seller.username,
email: req.body.seller.email,
votes: req.body.seller.votes
};
try {
item.seller = await findOrCreateUser(user,connection);
var user_id = await addItem(item,connection);
var items = await selectUserItems(user_id, connection);
connection.connection.release();
res.status(200).json(result);
} catch(error) {
res.status(500).end(error);
}
});
process.on('uncaughtException', error => console.error('Uncaught exception: ', error));
process.on('unhandledRejection', error => {console.error('Unhandled rejection: ', error));
app.listen(8000, function () {
console.log('App listening on port 8000')
});
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