Post request from fetch gives a 404 server error (javascript/express)

Question

I'm trying to see if a post request would work on my server at the '/db' route. The get request works just fine, but the 'Post' request gives a '404' not found error.

(Part of) my js code:

function getReq() {
    let p = fetch("http://localhost:3000/db").then((a)=>a.json()).then((x)=>console.log(x))
}

    async function postReq(obj) {
        console.log(obj)
        const p = await fetch("http://localhost:3000/db",
            {
                method: 'POST',
                headers: {'Content-Type': 'application/json'},
                body: obj
            }
        )
    }

My express code:

const app = express();
app.use(bodyParser.json());

app.get('/db', (req,res)=>
{
    res.sendFile("db.json");
});

app.post("/db", function(req,res) 
{
    res.send("ok");
});

app.use(express.static('public'));
app.listen(3000, (ok) => console.log("Okk"));

db.json and app.js are in the same folder, and I only call postReq with json strings. The rest of the files are in the 'public' directory. Could anyone guide me to what I could be doing wrong? Thank you.

Batuhan · Accepted Answer · 2022-05-31 22:37:01Z

2

You need to stringify the body because your content-type is application/json

async function postReq(obj) {
        console.log(obj)
        const p = await fetch("http://localhost:3000/db",
            {
                method: 'POST',
                headers: {'Content-Type': 'application/json'},
                body: JSON.stringify(obj) // Here 
            }
        )
    }

answered May 31, 2022 at 22:37

Batuhan

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3 Comments

Dudu Dudu Over a year ago

The obj passed as a parameter is already a json string, that's why i didnt stringify it again

Batuhan Over a year ago

It is not JSON string it is Javascript Object. stringify() is used to convert JSON to JSON String. It serializes a JavaScript object into a JSON String. You have to send the body as stringified JSON for the conversion for the backend. This is restriction of content-type: application/json

traktor Over a year ago

@DuduDudu Possibly test code passed a primitive (JavaScript) string to postReq as its argument. In general JavaScript string values are not valid JSON text, although on occasion they can be. If you did pass valid JSON text to postReq, please update the question with details because this answer does remove the 404 error generated by bodyParser middleware.

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