n8n/packages/nodes-base/nodes/WriteBinaryFile.node.ts

import {
	BINARY_ENCODING,
	IExecuteFunctions,
	IExecuteSingleFunctions
} from 'n8n-core';
import {
	IDataObject,
	INodeExecutionData,
	INodeType,
	INodeTypeDescription,
} from 'n8n-workflow';

import {
	writeFile as fsWriteFile,
} from 'fs';
import { promisify } from 'util';

const fsWriteFileAsync = promisify(fsWriteFile);


export class WriteBinaryFile implements INodeType {
	description: INodeTypeDescription = {
		displayName: 'Write Binary File',
		name: 'writeBinaryFile',
		icon: 'fa:file-export',
		group: ['output'],
		version: 1,
		description: 'Writes a binary file to disk',
		defaults: {
			name: 'Write Binary File',
			color: '#CC2233',
		},
		inputs: ['main'],
		outputs: ['main'],
		properties: [
			{
				displayName: 'File Name',
				name: 'fileName',
				type: 'string',
				default: '',
				required: true,
				placeholder: '/data/example.jpg',
				description: 'Path to which the file should be written.',
			},
			{
				displayName: 'Property Name',
				name: 'dataPropertyName',
				type: 'string',
				default: 'data',
				required: true,
				description: 'Name of the binary property which contains<br />the data for the file to be written.',
			},
		],
	};


	async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
				
		const items = this.getInputData();

		const returnData: INodeExecutionData[] = [];
		const length = items.length as unknown as number;
		let item: INodeExecutionData;

		for (let itemIndex = 0; itemIndex < length; itemIndex++) {

			const dataPropertyName = this.getNodeParameter('dataPropertyName', itemIndex) as string;
			
			const fileName = this.getNodeParameter('fileName', itemIndex) as string;
						
			item = items[itemIndex];

			if (item.binary === undefined) {
				throw new Error('No binary data set. So file can not be written!');
			}

			if (item.binary[dataPropertyName] === undefined) {
				throw new Error(`The binary property "${dataPropertyName}" does not exist. So no file can be written!`);
			}

			// Write the file to disk
			await fsWriteFileAsync(fileName, Buffer.from(item.binary[dataPropertyName].data, BINARY_ENCODING), 'binary');

			const newItem: INodeExecutionData = {
				json: {},
			};
			Object.assign(newItem.json, item.json);

			if (item.binary !== undefined) {
				// Create a shallow copy of the binary data so that the old
				// data references which do not get changed still stay behind
				// but the incoming data does not get changed.
				newItem.binary = {};
				Object.assign(newItem.binary, item.binary);
			}

			// Add the file name to data
			
			(newItem.json as IDataObject).fileName = fileName;

			returnData.push(newItem);
		}
		return this.prepareOutputData(returnData);
	}

}