I have a simple JavaScript server to process a POST command. But my post data shows up surrounded with braces and quotes. I'm using curl to send this:

curl --data {title:'Odessey',author:'Homer'} localhost:4444/test/add

But my server gets the posted data like this:

{ "{title:'Odessey',author:'Homer'}": '' }

When I send it back to the client, it shows up with spaces removed and quotes converted:

{"{title:'Odessey',author:'Homer'}":""}

Curiously, if I put quotes around the string in curl, I get exactly the same thing:

curl --data "{title:'Odessey',author:'Homer'}" localhost:4444/test/add

I'm running this on Windows 10. The problem doesn't seem to be with curl, because I wrote another (clumsier) server without using express, and this problem didn't show up. Also, I've tried curl's other options for sending data, like --data.ascii and --data.raw, but none of them help. So the problem must be with the express server.

Also, I log the req's Content-Type before processing the POST DATA. By default, it prints out application/x-www-form-urlencoded. At the suggestion of other users, I changed the Content-Type header in the curl statement by saying curl -H Content-Type:application/json, but that didn't help. The log statement confirms that it received this header, but then it fails to read the data at all, logging req.body: {}.

Here's my server code:

const express = require('express');
const app = express();

// taking this block out doesn't help. Without it, I don't get any data.  
app.use(
    express.urlencoded({ extended: true })
);

// Changing this to express.text() doesn't help. Nor does removing it.
app.use(express.json());

app.post('/test/add', (req, res) => {
    let hdr = "Content-Type";
    console.log(hdr, req.header(hdr)); 
    console.log("req.body:", req.body);
    res.send(req.body);
})

var server = app.listen(4444, function() {
    var urlStr = "http://" + host + ':' + port;
    console.log ("Example app listeneing at", urlStr);
})

Note: I have updated this slightly since I first posted it.