Express 向 Postman 请求返回一个空的 req.body

Question

I'm trying to set up a simple CRUD app. I've set up the DELETE route in express, and I'm trying to hit it using Postman.

When I log req.body on the request, I get an empty object.

The route:

var router = express.Router();

if (process.env.NODE_ENV !== 'production') {
    require('dotenv').config();
};

username = process.env.MONGODB_USERNAME;
password = process.env.MONGODB_PASSWORD;

const MongoClient = require('mongodb').MongoClient;
const connectionString = `mongodb://${username}:${password}@localhost:27017`

/* DELETE post delete. */
router.delete('/', (req, res) => {
    const postId = req.body.postId;
    console.log(req.body);
    console.log(postId);
    MongoClient.connect(connectionString, {useUnifiedTopology: true})
    .then(client => {
        console.log("Delete request to database!");
        const db = client.db("blog");
        const postsCollection = db.collection('blogPosts');
        postsCollection.findOneAndDelete({"_id": postId})
        .then(deletedDocument => {
            if(deletedDocument) {
              console.log(`Successfully deleted document that had the form: ${deletedDocument}.`)
              res.send(`Successfully deleted document that had the form: ${deletedDocument}.`);
            } else {
              console.log("No document matches the provided query.")
              res.send("No document matches the provided query.");
            }
            return deletedDocument
          })
          .catch(err => console.error(`Failed to find and delete document: ${err}`));
    })
    .catch(error => console.error(error));
});

module.exports = router;

The Postman request:

The Express app.js:

var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var postRequestRouter = require('./routes/postrequest');
// var adminRouter = require('./routes/admin');
var postDeleteRouter = require('./routes/postdelete');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/users', usersRouter);
app.use('/postrequest', postRequestRouter);
// app.use('/admin', adminRouter);
app.use('/postdelete', postDeleteRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

The resulting console logs:

{}
undefined
Delete request to database!
Successfully deleted document that had the form: [object Object].
DELETE /postdelete 200 43.848 ms - 7

I understand that the request to MongoDB itself is likely to fail because it isn't formatted correctly, but for now I'm just trying to understand why req.body is empty.

Any help would be appreciated!

Answer 1

Shortly after posting this question, I linked it to a programming Discord. A user going by "nnari" quickly figured out what was wrong.

Turns out I simply needed to change the dropdown in Postman from "Text" to "Json".