空体的请求

Question

在POST之后得到db：

[
    {
        "_id": "5420ccba19371ce81026cbdd",
        "__v": 0
    }
]

表示模型

var mongoose    = require( 'mongoose' ),
    Schema      = mongoose.Schema;

var problemSchema = new Schema({
  title:        String,
  grade:        String,
  author:       String
});

module.exports = mongoose.model('Problem', problemSchema);

路由器：

router.route( '/problems' )
  // get user list 
  .get( function ( req, res ) {
    Problem.find( function ( err, problems ) {
        if (err) {
          return res.send( err );
        }

        res.json ( problems );
      }
    );
  })
  // create a user
  .post( function ( req, res ) {
    var problem = new Problem( req.body );
    console.log( JSON.stringify( req.body ) );
    console.log( JSON.stringify( problem ) );

    problem.save( function ( err ) {
      if ( err ) {
        return res.send( err );
      }
      res.send( { message: 'Problem Added' } );
    });
});

应用程式：

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

// routes
// var users       = require( './routes/users' ),
var    problems    = require( './routes/problems' );



var app = express(); //Create the Express app



//connect to our database
//Ideally you will obtain DB details from a config file
var db = 'test';
var connectionString = 'mongodb://localhost:27017/' + db;



// connection func
mongoose.connect( connectionString );



// serve static files / client application
app.use( express.static( __dirname + '/public' ) );



//configure body-parser
app.use( bodyParser.json() );
app.use( bodyParser.urlencoded() );



//This is our route middleware
// app.use( '/api', users ); 
app.use( '/api', problems );



module.exports = app;

为什么？

ps postman POST：