Socket hang up when using axios - node.js

Question

I'm having an error "Error: socket hang up" and I don't know what causes this but it saves the data in database.
here's my code:
dataschema.js
const mongoose = require("mongoose");
const DataSchema = new mongoose.Schema({
data1: {
type: String
},
data2: {
type: String
},
data3: {
type: String
},
data4: {
type: String
},
});
const DataModel = mongoose.model("TEST123", DataSchema);
module.exports = DataModel;
routes.js
const express = require("express");
const app = express();
const mongoose = require("mongoose");
const DataModel = require('./models/dataschema');
var bodyParser = require('body-parser');
app.use(bodyParser.json());
mongoose.connect(
"mongodb://localhost:27017/stocksmonitor?readPreference=primary&appname=MongoDB%20Compass%20Community&ssl=false",
{ useNewUrlParser: true }
);
app.post('/insert', (req, res) => {
const stock = new DataModel({
data1: req.body[0],
data2: req.body[1],
data3: req.body[2],
data4: req.body[3],
})
stock.save();
})
app.listen(3001, () => {
console.log("You are connected");
})
savedata.js
const axios = require('axios');
SaveInfo = () => {
const testdata = ["a", "b", "c", "d"]
axios({
method: 'post',
url: 'http://localhost:3001/insert',
data: testdata
})
.then(function (response) {
console.log(response);
})
.catch(function (error) {
console.log(error);
});
}
SaveInfo();

Answer 1

I inspected the code and found that you did not return response for your controller. In the code below after the save add res.send() or res.json(). So express can return a proper response. Otherwise request will timed out, because it did not resolve and Express will cut the connection. Therefore axios is throwing Error: Socket hang up unexpectedly.
app.post('/insert', (req, res) => {
const stock = new DataModel({
data1: req.body[0],
data2: req.body[1],
data3: req.body[2],
data4: req.body[3],
})
stock.save();
})