TypeError: Cannot create property '_id' on string '{“[object Object]”:“”}'

问题

I'm trying to post form data, but I'm getting the following error on submit:

TypeError: Cannot create property '_id' on string '{"[object Object]":""}'.

My post was successfully captured:

Movie {id: "8", firstname: "test", lastname: "test", hero: "test", photo: "xxxxxxxx"}

But the data is not saved in MongoDB. I'm using the MEAN stack with Angular2.

My server.js:

//Need to write the Express code

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

var indexApi = require('./routes/index');
var movieApi = require('./routes/movie');

var port = 3000;

var app = express();

// parse application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
// parse application/vnd.api+json as json
//app.use(bodyParser.json({ type: 'application/json' }))

app.use('/',indexApi);
// Register the movie.js file
app.use('/api',movieApi);

// View Engine
app.set('views',path.join(__dirname, 'views'));
app.set('view engine','ejs');
app.engine('html',require('ejs').renderFile);

// Set static folder so that our all the things we read from client folder
app.use(express.static(path.join(__dirname,'client')));

app.listen(port,function(){
  console.log("Server started at port number : "+ port);
});

I post the data as follows:

 my app.component.ts:

 saveDetails(movieObj){
            //Note: I am getting the movie object here
            this.moviesService.saveMovie(movieObj).
                                            subscribe((data=> this.movieObj = JSON.stringify(data._body);
                                            console.log(this.movieObj);
                                             );

   }

  and movies.service.ts: 

    saveMovie(movie){
       //Note: I am getting the movie object here also
       var headers = new Headers();
       headers.append('Content-Type', 'application/x-www-form-urlencoded');
       return this.http.post('http://localhost:3000/api/movie',
                                        movie, {
                                        headers: headers});
    }

    movie.js:

    router.post('/movie',function(req,res){
        console.log("Under Post call....");
       var movieObj= req.body;

       // Note: here in the console everthing is comming as undefined thats is the problem
       console.log("[_id]"+movieObj._id+"[id]"+movieObj.id+"[firstname]"+movieObj.firstname+"[lastname]"+movieObj.lastname+"[hero]"+movieObj.hero+"[photo]"+movieObj.photo);

        db.movies.save(movieObj,function(err,docs){
            if(err){
            res.send(err);
             }
             res.json(docs);
       });
});

The output what i am getting is {"_id":"590aad3ec7133419f056bc77","\"{\\"[object Object]\\":\\"\\",\\"_id\\":\\"590aa9c455f16d0eb440673e\\"}\"":""}]

When hitting the http://localhost:3000/api/movies url.

Note: The aim is to save data in MongoDB.

回答1:

MongoDB accepts an Object whereas you are passing a String.

Wrong

var jsontest = JSON.stringify(movieObj);

Correct

var jsontest=movieObj;

P.S : assuming req.body is correct movie object.

回答2:

You are already using app.use(bodyParser.json()); which parses the body of the message to a JavaScript object. You can pass this directly, omitting

var movieObj= req.body;
var jsontest = JSON.stringify(movieObj);

completely and just have

router.post('/movie',function(req,res){
    console.log("Under Post call....");
    db.movies.save(req.body, function(err,docs){ // req.body is js object, parsed by bodyParser
        if(err){
            res.send(err);
            return;
        }
        res.json(docs);
   });
});

来源：https://stackoverflow.com/questions/43764172/typeerror-cannot-create-property-id-on-string-object-object

标签

node.js

mongodb

express

mean-stack

angular2-services