Backend post request only reads as "undefined" JS-CodePudding

I am pretty new to JS so please go easy on me.

Im trying to increment a value in a JSON file in my JS backend application. Whenever I increment the associated value by the key, it creates a new section "undefined"

Here is the entire application:

const { response } = require("express");
const express = require("express");
const fs = require("fs").promises;
const path = require("path");

const app = express();

const dataFile = path.join(__dirname, "data.json");

//support POSTing form data wuth url encoded
app.use(express.json());


app.get("/poll", async (req, res) =>{
    //data is now the js object of the Json data json
    let data = JSON.parse(await fs.readFile(dataFile, "utf-8"));
    
    const totalVotes = Object.values(data).reduce((total, n) => total  =n, 0);
    
    data = Object.entries(data).map(([label, votes]) => {
        return{
            label,
            percentage: (((100 * votes) / totalVotes) || 0).toFixed(0) // or with 0 in the even that you divide by zero
        }
    });
    
    
    res.json(data);
    
});

app.use(express.urlencoded({ extended: true}));

app.post("/poll", async (req, res) => {
    const data = JSON.parse(await fs.readFile(dataFile, "utf-8"));

    data[req.body.add]  ;

    await fs.writeFile(dataFile, JSON.stringify(data));
    
    res.json(data);
});
app.listen(3000, () => console.log("Server is running ..."));

Here is my JSON file before I POST

{
"JavaScript":0,
"TypScript":10,
"Both":3}

Here is a picture of my POST request in Insomnia:

Here is my JSON file after a Post Requests

{
    "JavaScript": 0,
    "TypScript": 10,
    "Both": 3,
    "undefined": null
}

Here is is after a second POST request:

{
    "JavaScript": 0,
    "TypScript": 10,
    "Both": 3,
    "undefined": 1
}

I know it might be something very simple, but I am very inexperienced so any help would be greatly appreciated!

I tried including some additional middleware to enable bodyParsing as I saw in other posts but that did not fix the issue.

I also tried

console.logging(req.body)

,but that only printed "undefined".

EDIT: I found the problem, I wasn't sending the information in Insomnia correctly, I need to click the form type and either format a JSON input or select the "Form URL Encoded"" Option. Otherwise it doesn't recognize the format.

Thank you for your help!

CodePudding user response：

I tried your code in my device, it works fine on my device which means you are not properly sending post request.

And there is a bug in your logic of adding name , in which you increament the add property of data object but that property is not a number but a null so the number does not increments. Here is a simple fix...

app.post("/poll", async (req, res) => {
    const data = JSON.parse(await fs.readFile(dataFile, "utf-8"));
    let {add} = req.body;
    
    if(data[add] === 0 || data[add]) data[add]  ;
    else data[add] = 0;

    await fs.writeFile(dataFile, JSON.stringify(data));
    
    res.json(data);
});

CodePudding user response：

If req.body printed "undefined", req.body.add will also be equal to "undefined". This is causing the error. I haven't used Insomnia but when you send your POST request your "body" needs to be something like this:

"add": "variableName"