类型错误：无法读取未定义的属性“用户名”--

Question

 var express = require("express"); var app = express(); var morgan = require("morgan"); var mongoose = require("mongoose"); port = 8000; var User = require("./app/models/user"); mongoose.connect("mongodb://localhost:27017/tutorial", function (err) { if (err) { console.log("Disconnected: " + err); } else { console.log("connected"); } }); app.post("/users", function (req, res) { var user = new User(); user.username = req.body.username; user.email = req.body.email; user.password = req.body.password; user.save(); res.send("user created"); }); app.use(morgan("dev")); app.listen(port, function () { console.log("You are listen on port " + port); });

TypeError: Cannot read property 'username' of undefined at D:\\MEAN\\server.js:16:28 at Layer.handle [as handle_request] (D:\\MEAN\\node_modules\\express\\lib\\router\\layer.js:95:5) at next (D:\\MEAN\\node_modules\\express\\lib\\router\\route.js:137:13) at Route.dispatch (D:\\MEAN\\node_modules\\express\\lib\\router\\route.js:112:3) at Layer.handle [as handle_request] (D:\\MEAN\\node_modules\\express\\lib\\router\\layer.js:95:5) at D:\\MEAN\\node_modules\\express\\lib\\router\\index.js:281:22 at Function.process_params (D:\\MEAN\\node_modules\\express\\lib\\router\\index.js:335:12) at next (D:\\MEAN\\node_modules\\express\\lib\\router\\index.js:275:10) at expressInit (D:\\MEAN\\node_modules\\express\\lib\\middleware\\init.js:40:5) at Layer.handle [as handle_request] (D:\\MEAN\\node_modules\\express\\lib\\router\\layer.js:95:5) at trim_prefix (D:\\MEAN\\node_modules\\express\\lib\\router\\index.js:317:13) at D:\\MEAN\\node_modules\\express\\lib\\router\\index.js:284:7 at Function.process_params (D:\\MEAN\\node_modules\\express\\lib\\router\\index.js:335:12) at next (D:\\MEAN\\node_modules\\express\\lib\\router\\index.js:275:10) at query (D:\\MEAN\\node_modules\\express\\lib\\middleware\\query.js:45:5) at Layer.handle [as handle_request] (D:\\MEAN\\node_modules\\express\\lib\\router\\layer.js:95:5)

Answer 1

Include a code to grab the request body using express method express.json which uses body parser module behind the scenes Eg

This should work

---

app.use(express.json())

Answer 2

If your post request comes as json as I presume it does you are going to need to somehow parse the request's body. You can do that by requiring "body-parser" and using it's json method like so:

const bodyParser = require('body-parser');
const app = require('express')();
app.use(bodyParser.json());

What we're saying with app.use(bodyParser.json()) is to use that body parser for every single route.