使用Express JS发布时出错

Question

I am testing the post method to create a todo item as follows. I am using postman in chrome to simulate the post method call. However, it does not work and gives me the below error. I suspect something is wrong with the way body-parser library is working. What am I doing wrong here?

1  SyntaxError: Unexpected token b
2:    at parse (/Users/zack/mydrive/proj/express-demo/node_modules/body-parser/lib/types/json.js:83:15)
3:    at /Users/zack/mydrive/proj/express-demo/node_modules/body-parser/lib/read.js:116:18
4:    at invokeCallback (/Users/zack/mydrive/proj/express-demo/node_modules/body-parser/node_modules/raw-body/index.js:262:16)
5:    at done (/Users/zack/mydrive/proj/express-demo/node_modules/body-parser/node_modules/raw-body/index.js:251:7)
6:    at IncomingMessage.onEnd (/Users/zack/mydrive/proj/express-demo/node_modules/body-parser/node_modules/raw-body/index.js:308:7)
7     at IncomingMessage.emit (events.js:104:17)
8     at _stream_readable.js:908:16

Code:

var express = require('express');
var app = express();
var handlebars = require('express-handlebars');
var bodyParser = require('body-parser');

//MIDDLEWARE
app.engine('handlebars', handlebars({defaultLayout: 'main'}));
app.set('view engine', 'handlebars');

app.use(bodyParser.json())
app.use(bodyParser.urlencoded({
  extended: true
}));

// TODOS
var todos = [
  { body: "take out the trash",completed: false},
  { body: "Do the laundry",completed:true},
  { body: "Make a screencast",completed:false}
]

app.post('/todos', function (req, res){
  console.log("todo:", req.body);
  var todo = req.body;
  console.log("todo:"+todo);
  todos.push(todo);
  res.status(200).json(todo);
  res.send('OK')
})

Further I observe that the problem is because of this line.

app.use(bodyParser.json());

Answer 1

Are you sure you are sending the request as JSON? Make sure you've selected it in Postman - https://imgur.com/j0M7TEX .

If that didn't work, you can try the following -

...

app.post('/todos', function (req, res){
  console.log("todo:", req.body);
  var todo = req.body;
  console.log("todo:"+todo);
  todos.push(todo);

  // Only try to send a single response.
  res.json(todo);
});

It looks like you were trying to send two responses, one containing JSON, and another with text/plain ('Ok').

http://expressjs.com/fr/api.html#res.json

Answer 2

It seems like your program is trying to interpret the post data as json data - and generating an error when it trys to parse the request data which is probably url-encoded.

Perhaps consider sending your data in json format. You will have to set the request headers to indicate the datatype is json. See this answer for an example:

Angular JS POST request not sending JSON data

Answer 3

I just created a new session in postman and it started working. I am not sure if there is a caching effect but it works now. I did not make any code change at all. Posting this as the solution now.

Answer 4

Just don't put quotes on your JSON value.

Not "okay2" but just okay2 .

I think that postman adds the quotes himself if needed and in this case creates ""okay2"" which isn't valid JSON.

By the way you can test by clicking on the "row" radio button and write your own JSON.