Creating excel file and writing to it with ExcelJS

Question

I wrote a script that creates a new excel file with ExcelJS. Adds 3 headers and inserts 2 rows. Then saves that file to disk.

In the next step it should read that previously saved file, add 1 row and save it again under a new name. I can't find the reason why the second part where I try to add 3rd row never happens. Both files look the same and there are no errors in console.

const Excel = require('exceljs');

async function exTest(){
  const workbook = new Excel.Workbook();
  const worksheet = workbook.addWorksheet("My Sheet");

worksheet.columns = [
  {header: 'Id', key: 'id', width: 10},
  {header: 'Name', key: 'name', width: 32}, 
  {header: 'D.O.B.', key: 'dob', width: 15,}
];

worksheet.addRow({id: 1, name: 'John Doe', dob: new Date(1970, 1, 1)});
worksheet.addRow({id: 2, name: 'Jane Doe', dob: new Date(1965, 1, 7)});

// save under export.xlsx
await workbook.xlsx.writeFile('export.xlsx');

// load a copy of export.xlsx
const newWorkbook = new Excel.Workbook();
await newWorkbook.xlsx.readFile('export.xlsx');

const newworksheet = newWorkbook.getWorksheet('My Sheet');
newworksheet.addRow(
  {id: 3, name: 'New Guy', dob: new Date(2000, 1, 1)}
);

await newWorkbook.xlsx.writeFile('export2.xlsx');

console.log("File is written");
};

exTest();

Answer 1

Solved it by adding array to describe columns in second part of the code. Then the 3rd row was added successfully. When passing an object with column names to addRow() I had to provide a description of columns that already existed in excel file.

const Excel = require('exceljs');

async function exTest(){
  const workbook = new Excel.Workbook();
  const worksheet = workbook.addWorksheet("My Sheet");

worksheet.columns = [
 {header: 'Id', key: 'id', width: 10},
 {header: 'Name', key: 'name', width: 32}, 
 {header: 'D.O.B.', key: 'dob', width: 15,}
];

worksheet.addRow({id: 1, name: 'John Doe', dob: new Date(1970, 1, 1)});
worksheet.addRow({id: 2, name: 'Jane Doe', dob: new Date(1965, 1, 7)});

// save under export.xlsx
await workbook.xlsx.writeFile('export.xlsx');

//load a copy of export.xlsx
const newWorkbook = new Excel.Workbook();
await newWorkbook.xlsx.readFile('export.xlsx');

const newworksheet = newWorkbook.getWorksheet('My Sheet');
newworksheet.columns = [
 {header: 'Id', key: 'id', width: 10},
 {header: 'Name', key: 'name', width: 32}, 
 {header: 'D.O.B.', key: 'dob', width: 15,}
];
await newworksheet.addRow({id: 3, name: 'New Guy', dob: new Date(2000, 1, 1)});

await newWorkbook.xlsx.writeFile('export2.xlsx');

console.log("File is written");

};

exTest();

Answer 2

Working link attached

const Excel = require('exceljs');

// Create workbook & add worksheet
const workbook = new Excel.Workbook();
const worksheet = workbook.addWorksheet('ExampleSheet');

// add column headers
worksheet.columns = [
  { header: 'Package', key: 'package_name' },
  { header: 'Author', key: 'author_name' }
];

// Add row using key mapping to columns
worksheet.addRow(
  { package_name: "ABC", author_name: "Author 1" },
  { package_name: "XYZ", author_name: "Author 2" }
);

// Add rows as Array values
worksheet
  .addRow(["BCD", "Author Name 3"]);

// Add rows using both the above of rows
const rows = [
  ["FGH", "Author Name 4"],
  { package_name: "PQR", author_name: "Author 5" }
];


worksheet
  .addRows(rows);

// save workbook to disk
workbook
  .xlsx
  .writeFile('sample.xlsx')
  .then(() => {
    console.log("saved");
  })
  .catch((err) => {
    console.log("err", err);
  });

https://repl.it/@vishwasc/ExcelJs-Example#index.js

image attachemnts

// add image to workbook by filename
const imageId1 = workbook.addImage({
  filename: 'path/to/image.jpg',
  extension: 'jpeg',
});

// add image to workbook by buffer
const imageId2 = workbook.addImage({
  buffer: fs.readFileSync('path/to.image.png'),
  extension: 'png',
});

// add image to workbook by base64
const myBase64Image = "data:image/png;base64,iVBORw0KG...";
const imageId2 = workbook.addImage({
  base64: myBase64Image,
  extension: 'png',
});

Note that in both cases, the extension must be specified. Valid extension values include 'jpeg', 'png', 'gif'.