Handling TypeError: Cannot read property error when trying to retrieve POST data in Express.js

In express.js, an HTTP web server library for the node.js language, you may encounter a TypeError: Cannot read property xx of undefined error when trying to retrieve POST data (body).

When sending an HTTP POST request with a request body to express.js, you get a TypeError: Cannot read property xx of undefined error.

curl http://192.168.0.110:8111/config -X POST -d 'content=hogehogehoge'

First, install the package:

npm install --save body-parser

Add the following code:

var bodyParser = require('body-parser')
app.use( bodyParser.json() );       // to support JSON-encoded bodies
app.use(bodyParser.urlencoded({     // to support URL-encoded bodies
  extended: true
})); 

Now you can retrieve HTTP POST data with req.body.value. Below, as per the curl command above, we use req.body.content to retrieve content.

app.post('/config', async (req, res, next) => {
  try {

    console.log(req.body.content) ; 

    res.send("something here.")

    next();
  } catch (error) {
    next(error);
  }

});

The method may vary depending on the version of express.js.

javascript - How to retrieve POST query parameters? - Stack Overflow