Node.js Express Project to Convert CSV to Array of JSON Objects Using csv-to-array Library in Javascript

Welcome folks today in this blog post we will be converting csv to array of json objects using csv-to-array library in javascript. All the full source code of the application is shown below.

Get Started

In order to get started you need to make a new node.js project using the below command as shown below

npm init -y

npm i express

npm i csv-to-array

npm i multer

And after that you will see the below directory structure of the app is shown below

Basic Example

Now we will be seeing the basic example to convert the csv file to array of json objects

index.js

var columns = ["Name", "Age", "Country"];
require("csv-to-array")(
  {
    file: "users.csv",
    columns: columns,
  },
  function (err, array) {
    console.log(err || array);
  }
);

var columns = ["Name", "Age", "Country"];

require("csv-to-array")(

{

file: "users.csv",

columns: columns,

function (err, array) {

console.log(err || array);

}

);

As you can see that in the above code we are importing the csv-to-array library and then we are giving the headers of the json objects. And then we are giving the filename of the csv file and passing the column names. And then we are showing the array of json objects inside the command line.

First of all you can create the users.csv file inside the root directory and copy paste the below code

This will produce the below result which contains the array of json objects as shown below

Express App

Now we can transform this to an actual express app by writing the below code inside the index.js file as shown below

index.js

let express = require("express");
let bodyparser = require("body-parser");
let fs = require("fs");
let app = express();
let multer = require("multer");

app.use(bodyparser.urlencoded({ extended: false }));
app.use(bodyparser.json());
app.use(express.static("public/uploads"));

let storage = multer.diskStorage({
  //multers disk storage settings
  destination: function (req, file, cb) {
    cb(null, "public/uploads");
  },
  filename: function (req, file, cb) {
    var datetimestamp = Date.now();
    cb(
      null,
      file.fieldname +
        "-" +
        datetimestamp +
        "." +
        file.originalname.split(".")[file.originalname.split(".").length - 1]
    );
  },
});

let upload = multer({
  storage: storage,
});

app.get("/", (req, res) => {
  res.sendFile(__dirname + "/index.html");
});

app.post("/convert", upload.single("file"), (req, res) => {

  var columns = ["Name", "Age", "Country"];

  let outputfilename = Date.now() + "output.json";

  require("csv-to-array")(
    {
      file: req.file.path,
      columns: columns,
    },
    function (err, array) {
      console.log(err || array);

      // stringify JSON Object

      fs.writeFile(outputfilename, JSON.stringify(array), "utf8", function (err) {
        if (err) {
          console.log("An error occured while writing JSON Object to File.");
          return console.log(err);
        }

        console.log("JSON file has been saved.");

        res.download(outputfilename, () => {});
      });
    }
  );
});

app.listen(5000, () => {
  console.log("App is listening on port 5000");
});

let express = require("express");

let bodyparser = require("body-parser");

let fs = require("fs");

let app = express();

let multer = require("multer");

app.use(bodyparser.urlencoded({ extended: false }));

app.use(bodyparser.json());

app.use(express.static("public/uploads"));

let storage = multer.diskStorage({

//multers disk storage settings

destination: function (req, file, cb) {

cb(null, "public/uploads");

filename: function (req, file, cb) {

var datetimestamp = Date.now();

cb(

null,

file.fieldname +

"-" +

datetimestamp +

"." +

file.originalname.split(".")[file.originalname.split(".").length - 1]

);

});

let upload = multer({

storage: storage,

});

app.get("/", (req, res) => {

res.sendFile(__dirname + "/index.html");

});

app.post("/convert", upload.single("file"), (req, res) => {

var columns = ["Name", "Age", "Country"];

let outputfilename = Date.now() + "output.json";

require("csv-to-array")(

{

file: req.file.path,

columns: columns,

function (err, array) {

console.log(err || array);

// stringify JSON Object

fs.writeFile(outputfilename, JSON.stringify(array), "utf8", function (err) {

if (err) {

console.log("An error occured while writing JSON Object to File.");

return console.log(err);

}

console.log("JSON file has been saved.");

res.download(outputfilename, () => {});

});

}

);

});

app.listen(5000, () => {

console.log("App is listening on port 5000");

});

As you can see we are loading the express and the csv-to-array library and then we are loading the index.html file when the user goes to the / route and then we are making a post request to the /convert route where we are getting the path of the uploaded csv file using the multer library. For this you need to make the public/uploads directory structure where we will be storing the files which is uploaded by the user. And then we will downloading the json file as an attachment.

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <form action="/convert" method="post" enctype="multipart/form-data">
        <input type="file" name="file" accept=".csv" required>
        <input type="submit" value="Download JSON File">
    </form>
</body>
</html>

<!DOCTYPE html>

<head>

<title>Document</title>

</head>

<body>

</form>

</body>

</html>