Node/Mongoose Error: ValidationError

Question

This is my server.js. When I run node server.js then use PostMan to post json, it gives me the following error.

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

app.use(bodyParser.json())

app.get('/api/posts', function(req, res) {
  res.json([
    {
      username: '@rodandrew95',
      body: 'node rocks!'
    }
  ])
})

app.listen(3000, function() {
  console.log('Server listening on', 3000)
})


var Post = require('./models/post')
app.post('/api/posts', function(req, res, next) {
  // console.log('post received')
  // console.log(req.body.username)
  // console.log(req.body.body)
  // res.sendStatus(201)
  var post = new Post({
    username: req.body.username,
    body: req.body.body
  });
  post.save(function (err, post) {
    if (err) { return next(err) }
    res.sendStatus(201).json(post)
  })
})

The error:

(node:6863) DeprecationWarning: Mongoose: mpromise (mongoose's default promise library) is deprecated, plug in your own promise library instead: http://mongoosejs.com/docs/promises.html
ValidationError: Post validation failed
    at MongooseError.ValidationError (/Users/andrewrodrigues/Desktop/write_modern/ch_1/node_modules/mongoose/lib/error/validation.js:23:11)
    at model.Document.invalidate (/Users/andrewrodrigues/Desktop/write_modern/ch_1/node_modules/mongoose/lib/document.js:1486:32)
    at /Users/andrewrodrigues/Desktop/write_modern/ch_1/node_modules/mongoose/lib/document.js:1362:17
    at validate (/Users/andrewrodrigues/Desktop/write_modern/ch_1/node_modules/mongoose/lib/schematype.js:705:7)
    at /Users/andrewrodrigues/Desktop/write_modern/ch_1/node_modules/mongoose/lib/schematype.js:742:9
    at Array.forEach (native)
    at SchemaString.SchemaType.doValidate (/Users/andrewrodrigues/Desktop/write_modern/ch_1/node_modules/mongoose/lib/schematype.js:710:19)
    at /Users/andrewrodrigues/Desktop/write_modern/ch_1/node_modules/mongoose/lib/document.js:1360:9
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)

I'm trying to learn the MEAN stack through "Write Modern Web Apps with the MEAN Stack" but I'm running into issues all the time, even when I follow the code and instructions exactly. Can anyone help understand this error, and possibly recommend some good resources for learning the mean stack?

Answer 1

This error is triggered because you have provided a mongoose validation in your schema (in /models/post ) and that validation is failing.

For instance, if you provided your model like this :

var postSchema = new Schema({

    "username": String,
    "body": String,
    "email": {
        type: String,
        required: true
    }

});
var Post = mongoose.model('Post', postSchema);

This would fail because email required validator is not respected. Find a full list of validators here .

Side note : res.sendStatus(201).json(post) will set the json body and content-type header after sending a response with 201 status. To send both use :

res.status(201).json(post)