n8n Excel Form Writer Node

This package provides a custom n8n node to fill data into an existing Excel template file.

Description

The ExcelFormWriter node allows you to:

1. Load an Excel template (.xlsx).
2. Write values to specific cells based on dynamic input.
3. Save the result as a new Excel file.

This is useful for automating the creation of reports, invoices, or any other document based on a fixed Excel form.

Features

• Load an Excel template from a specified path.
• Write data to any number of cells using a dynamic JSON input.
• Save the modified workbook to a new path.
• Advanced options for handling existing output files (overwrite, rename, or error).
• Returns a success message and the path to the newly created file.

Node Properties

Template File Path

Required. The absolute path to the Excel template file (e.g., /data/formular.xlsx). Can be set dynamically using an n8n expression.

Output File Path

Required. The absolute path where the new Excel file will be saved (e.g., /data/formular-ausgefuellt.xlsx). Can be set dynamically using an n8n expression.

Cell Data (JSON)

Required. A JSON array of objects, where each object specifies a cell and the value to write. This field is the core of the node and can be populated dynamically using an n8n expression from a previous node.

Additional Options

Under "Additional Options", you can configure how the node behaves in specific scenarios.

• If File Exists: Determines the action to take if the output file already exists.
  • Overwrite: Replaces the existing file (Default).
  • Error: Throws an error and stops the workflow.
  • Rename: Appends a number to the filename (e.g., file-1.xlsx).

JSON Data Examples

The Cell Data (JSON) field expects a valid JSON array. This can be provided directly, or more powerfully, as an expression from a previous node (like a Function node or an HTTP Request node).

Example 1: Basic Data Entry

This fills out a simple invoice or contact form.

[
  { "cell": "B2", "value": "INV-2024-105" },
  { "cell": "B3", "value": "Max Mustermann" },
  { "cell": "B4", "value": "Musterstraße 1" },
  { "cell": "E2", "value": "2024-10-15" }
]

Example 2: Using Different Data Types

exceljs supports numbers, booleans, and dates, not just strings.

[
  { "cell": "A1", "value": "Product Report" },
  { "cell": "B2", "value": 150 },
  { "cell": "C2", "value": 200.50 },
  { "cell": "D2", "value": true },
  { "cell": "E2", "value": { "formula": "B2*C2", "result": 30100 } }
]

Example 3: Dynamic JSON from a Function Node

Imagine a Function node prepares the following data in a field called excelData.

// In a Function node
const items = [
  { sku: 'X-01', qty: 5 },
  { sku: 'Y-02', qty: 12 },
];

let row = 10; // Start writing at row 10
const excelData = [];

for (const item of items) {
  excelData.push({ cell: `A${row}`, value: item.sku });
  excelData.push({ cell: `B${row}`, value: item.qty });
  row++;
}

return [{ json: { excelData } }];

You would then use the expression {{ $json.excelData }} in the Cell Data (JSON) field of the Excel Form Writer node.

Example Usage

To use this node, you need to provide the path to your template, the desired output path, and the data to be filled in. The cellData parameter accepts an array of objects.

License

MIT

Credits

This node is powered by the excellent exceljs library, which handles all the heavy lifting of Excel file manipulation.