How to convert a nested json object into an excel table using the xlsx npm library?

Question

I've got a nested json object. For the sake of simplicity:

data = {'key1': 1, 'key2': 2, 'key3': {'nestedKey1': 3, 'nestedKey2': 4}}

A real object is bigger but the point is that it's a nested one. Values may be strings, numbers or other objects. Now I need to get an excel table that (for this specific json would look like this):

|----------------------------------------
| key1 | key2 |           key3          |
|      |      |--------------------------
|      |      | nestedKey1 | nestedKey2 |
|----------------------------------------
|  1   |  2   |     3      |      4     |
|----------------------------------------

In order to do this I tried using the xlsx library. I import the lib as follows:

import { WorkSheet, WorkBook, utils, writeFile } from 'xlsx';

Inside my method I define the object:

let myObj = {'key1': 1, 'key2': 2, 'key3': {'nestedKey1': 3, 'nestedKey2': 4}}

then I create a worksheet and workbook:

const workSheet: WorkSheet = utils.json_to_sheet([myObj]);
const workBook: WorkBook = utils.book_new();
utils.book_append_sheet(workBook, workSheet, 'object_to_save');

and finally write it to a file:

writeFile(workBook, 'Tests.xlsx');

But quite expectedly it doesn't process the nested object the way I would like it to. I can't figure out what I should do to get the desired result.

Answer 1

Using excel4node we can do it easily.

Here to display the JSON I created the table, and convert the JSON according to my requirement.

Here is the solution in node.js:

const express = require("express");
const excelgenerate = require("excel4node");
const app = express();

//To serve static files such as images, CSS files, and JavaScript files
app.use(express.static('./public'));

// Parse JSON bodies (as sent by API clients)
app.use(express.json());

// Parse URL-encoded bodies (as sent by HTML forms)
app.use(express.urlencoded({ extended: true }));

//Create a new instance of a Workbook class
const wb = new excelgenerate.Workbook();

const heading = ["Full Name", "Email"];

const heading1 = ["First Name", "Last name", " "];

const data = [
  {
    first_name: "Johns",
    last_name: "Does",
    email: "[email protected]",
  },
  {
    first_name: "JP",
    last_name: "Smith",
    email: "[email protected]",
  },
  {
    first_name: "Test",
    last_name: "Team",
    email: "[email protected]",
  },
];

//creating dynamik tr td for table
let datas = [];
datas.push(`<tr>
<th colspan="2">${heading[0]}</th>
<th>${heading[1]}</th>
</tr>`);

datas.push(`<tr>
<th>${heading1[0]}</th>
<th>${heading1[1]}</th>
<th>${heading1[2]}</th>
</tr>`);
data.map((value) => {
  datas.push(`<tr>
        <td>${value.first_name}</td>
        <td>${value.last_name}</td>
        <td>${value.email}</td>
    </tr>`);
});

//remove , from array
datas = datas.join("");

app.get("/", (req, res) => {
  try {
    res.send(`
    <style>
        table {
            font-family: arial, sans-serif;
            border-collapse: collapse;
            width: 100%;
        }
        
        td, th {
            border: 1px solid #dddddd;
            text-align: left;
            padding: 8px;
        }
    </style>
    <div style="margin:100px">
        <form action="/convert" method="post">
            <div class="form-group">
            <input type="submit" value="Convert To Excel!" class="btn btn-default">
            <table>
                ${datas}
            </table>            
            </div>
        </form>
    </div>
    `);
  } catch (error) {
    throw error;
  }
});

app.post("/convert", (req, res) => {
    try {
      // Add Worksheets to the workbook
      const ws = wb.addWorksheet("Sheet 1");
  
      // Create a reusable style
      var style = wb.createStyle({
        font: {
          size: 12,
        },
      });

      ws.cell(1, 1, 1, 2, true).string(heading[0]).style({ font: { size: 14 } });
      ws.cell(1, 3).string(heading[1]).style({ font: { size: 14 } });

      for (let index = 1; index < 4; index++) {
        ws.column(index).setWidth(25);
        ws.cell(2, index)
          .string(heading1[index - 1])
          .style(style)
          .style({ font: { size: 14 } });
      }
  
      for (let index = 0; index < data.length; index++) {
        ws.cell(index + 3, 1)
          .string(data[index].first_name)
          .style(style);
        ws.cell(index + 3, 2)
          .string(data[index].last_name)
          .style(style);
        ws.cell(index + 3, 3)
          .string(data[index].email)
          .style(style);
      }
  
      wb.write("public/files/Excel.xlsx");
      let fname = "Excel.xlsx";
  
      res.send(`<div style="margin:100px">
      <a href="ms-excel:ofe|u|file:///E:/javascript-jquery/multiselect-master/${fname}">
            <input type="button" value="Open In App" class="btn btn-default">
      </a>
      <br>
      <br>
      <a href="/files/${fname}" target="_blank">
        <input type="button" value="Download" class="btn btn-default">
      </a>
      </div>`);
    } catch (e) {
      throw e;
    }
  });

app.listen(3000, () => {
  console.log(`App running at http://localhost:3000`);
});

Output