Build a programmatic-style node

This tutorial walks through building a programmatic-style node. Before you begin, make sure this is the node style you need. Refer to Choose your node building approach for more information.

Prerequisites

You need the following installed on your development machine:

• git
• Node.js and npm. Minimum version Node 18.17.0. You can find instructions on how to install both using nvm (Node Version Manager) for Linux, Mac, and WSL here. For Windows users, refer to Microsoft's guide to Install NodeJS on Windows.

You need some understanding of:

• JavaScript/TypeScript
• REST APIs
• git
• Expressions in n8n

Build your node

In this section, you'll clone n8n's node starter repository, and build a node that integrates the SendGrid. You'll create a node that implements one piece of SendGrid functionality: create a contact.

Step 1: Set up the project

n8n provides a starter repository for node development. Using the starter ensures you have all necessary dependencies. It also provides a linter.

Clone the repository and navigate into the directory:

1. Generate a new repository from the template repository.
2. Clone your new repository:

   git clone https://github.com/<your-organization>/<your-repo-name>.git n8n-nodes-friendgrid
   cd n8n-nodes-friendgrid

The starter contains example nodes and credentials. Delete the following directories and files:

• nodes/ExampleNode
• nodes/HTTPBin
• credentials/ExampleCredentials.credentials.ts
• credentials/HttpBinApi.credentials.ts

Now create the following directories and files:

nodes/FriendGrid
nodes/FriendGrid/FriendGrid.node.json
nodes/FriendGrid/FriendGrid.node.ts
credentials/FriendGridApi.credentials.ts

These are the key files required for any node. Refer to Node file structure for more information on required files and recommended organization.

Now install the project dependencies:

npm i

Step 2: Add an icon

Save the SendGrid SVG logo from here as friendGrid.svg in nodes/FriendGrid/.

n8n recommends using an SVG for your node icon, but you can also use PNG. If using PNG, the icon resolution should be 60x60px. Node icons should have a square or near-square aspect ratio.

Step 3: Define the node in the base file

Every node must have a base file. Refer to Node base file for detailed information about base file parameters.

In this example, the file is FriendGrid.node.ts. To keep this tutorial short, you'll place all the node functionality in this one file. When building more complex nodes, you should consider splitting out your functionality into modules. Refer to Node file structure for more information.

Step 3.1: Imports

Start by adding the import statements:

import {
	IExecuteFunctions,
} from 'n8n-core';

import {
	IDataObject,
	INodeExecutionData,
	INodeType,
	INodeTypeDescription,
    NodeConnectionType
} from 'n8n-workflow';

import {
	OptionsWithUri,
} from 'request';

Step 3.2: Create the main class

The node must export an interface that implements INodeType. This interface must include a description interface, which in turn contains the properties array.

export class FriendGrid implements INodeType {
	description: INodeTypeDescription = {
		// Basic node details will go here
		properties: [
			// Resources and operations will go here
		],
	};
	// The execute method will go here
	async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
	}
}

Step 3.3: Add node details

All programmatic nodes need some basic parameters, such as their display name and icon. Add the following to the description:

displayName: 'FriendGrid',
name: 'friendGrid',
icon: 'file:friendGrid.svg',
group: ['transform'],
version: 1,
description: 'Consume SendGrid API',
defaults: {
	name: 'FriendGrid',
},
inputs: [NodeConnectionType.Main],
outputs: [NodeConnectionType.Main],
credentials: [
	{
		name: 'friendGridApi',
		required: true,
	},
],

n8n uses some of the properties set in description to render the node in the Editor UI. These properties are displayName, icon, and description.

Step 3.4: Add the resource

The resource object defines the API resource that the node uses. In this tutorial, you're creating a node to access one of SendGrid's API endpoints: /v3/marketing/contacts. This means you need to define a resource for this endpoint. Update the properties array with the resource object:

{
	displayName: 'Resource',
	name: 'resource',
	type: 'options',
	options: [
		{
			name: 'Contact',
			value: 'contact',
		},
	],
	default: 'contact',
	noDataExpression: true,
	required: true,
	description: 'Create a new contact',
},

type controls which UI element n8n displays for the resource, and tells n8n what type of data to expect from the user. options results in n8n adding a dropdown that allows users to choose one option. Refer to Node UI elements for more information.

Step 3.5: Add operations

The operations object defines what you can do with a resource. It usually relates to REST API verbs (GET, POST, and so on). In this tutorial, there's one operation: create a contact. It has one required field, the email address for the contact the user creates.

Add the following to the properties array, after the resource object:

{
	displayName: 'Operation',
	name: 'operation',
	type: 'options',
	displayOptions: {
		show: {
			resource: [
				'contact',
			],
		},
	},
	options: [
		{
			name: 'Create',
			value: 'create',
			description: 'Create a contact',
			action: 'Create a contact',
		},
	],
	default: 'create',
	noDataExpression: true,
},
{
	displayName: 'Email',
	name: 'email',
	type: 'string',
	required: true,
	displayOptions: {
		show: {
			operation: [
				'create',
			],
			resource: [
				'contact',
			],
		},
	},
	default:'',
	placeholder: 'name@email.com',
	description:'Primary email for the contact',
},

Step 3.6: Add optional fields

Most APIs, including the SendGrid API that you're using in this example, have optional fields you can use to refine your query.

To avoid overwhelming users, n8n displays these under Additional Fields in the UI.

For this tutorial, you'll add two additional fields, to allow users to enter the contact's first name and last name. Add the following to the properties array:

{
	displayName: 'Additional Fields',
	name: 'additionalFields',
	type: 'collection',
	placeholder: 'Add Field',
	default: {},
	displayOptions: {
		show: {
			resource: [
				'contact',
			],
			operation: [
				'create',
			],
		},
	},
	options: [
		{
			displayName: 'First Name',
			name: 'firstName',
			type: 'string',
			default: '',
		},
		{
			displayName: 'Last Name',
			name: 'lastName',
			type: 'string',
			default: '',
		},
	],
},

Step 4: Add the execute method

You've set up the node UI and basic information. It's time to map the node UI to API requests, and make the node actually do something.

The execute method runs every time the node runs. In this method, you have access to the input items and to the parameters that the user set in the UI, including the credentials.

Add the following the execute method in the FriendGrid.node.ts:

// Handle data coming from previous nodes
const items = this.getInputData();
let responseData;
const returnData = [];
const resource = this.getNodeParameter('resource', 0) as string;
const operation = this.getNodeParameter('operation', 0) as string;

// For each item, make an API call to create a contact
for (let i = 0; i < items.length; i++) {
	if (resource === 'contact') {
		if (operation === 'create') {
			// Get email input
			const email = this.getNodeParameter('email', i) as string;
			// Get additional fields input
			const additionalFields = this.getNodeParameter('additionalFields', i) as IDataObject;
			const data: IDataObject = {
				email,
			};

			Object.assign(data, additionalFields);

			// Make HTTP request according to https://sendgrid.com/docs/api-reference/
			const options: OptionsWithUri = {
				headers: {
					'Accept': 'application/json',
				},
				method: 'PUT',
				body: {
					contacts: [
						data,
					],
				},
				uri: `https://api.sendgrid.com/v3/marketing/contacts`,
				json: true,
			};
			responseData = await this.helpers.requestWithAuthentication.call(this, 'friendGridApi', options);
			returnData.push(responseData);
		}
	}
}
// Map data to n8n data structure
return [this.helpers.returnJsonArray(returnData)];

Note the following lines of this code:

const items = this.getInputData();
... 
for (let i = 0; i < items.length; i++) {
	...
	const email = this.getNodeParameter('email', i) as string;
	...
}

Users can provide data in two ways:

• Entered directly in the node fields
• By mapping data from earlier nodes in the workflow

getInputData(), and the subsequent loop, allows the node to handle situations where data comes from a previous node. This includes supporting multiple inputs. This means that if, for example, the previous node outputs contact information for five people, your FriendGrid node can create five contacts.

Step 5: Set up authentication

The SendGrid API requires users to authenticate with an API key.

Add the following to FriendGridApi.credentials.ts

import {
	IAuthenticateGeneric,
	ICredentialTestRequest,
	ICredentialType,
	INodeProperties,
} from 'n8n-workflow';

export class FriendGridApi implements ICredentialType {
	name = 'friendGridApi';
	displayName = 'FriendGrid API';
	properties: INodeProperties[] = [
		{
			displayName: 'API Key',
			name: 'apiKey',
			type: 'string',
			default: '',
		},
	];

	authenticate: IAuthenticateGeneric = {
		type: 'generic',
		properties: {
			headers: {
				Authorization: '=Bearer {{$credentials.apiKey}}',
			},
		},
	};

	test: ICredentialTestRequest = {
		request: {
			baseURL: 'https://api.sendgrid.com/v3',
			url: '/marketing/contacts',
		},
	};
}

For more information about credentials files and options, refer to Credentials file.

Step 6: Add node metadata

Metadata about your node goes in the JSON file at the root of your node. n8n refers to this as the codex file. In this example, the file is FriendGrid.node.json.

Add the following code to the JSON file:

{
	"node": "n8n-nodes-base.FriendGrid",
	"nodeVersion": "1.0",
	"codexVersion": "1.0",
	"categories": [
		"Miscellaneous"
	],
	"resources": {
		"credentialDocumentation": [
			{
				"url": ""
			}
		],
		"primaryDocumentation": [
			{
				"url": ""
			}
		]
	}
}

For more information on these parameters, refer to Node codex files.

Step 7: Update the npm package details

Your npm package details are in the package.json at the root of the project. It's essential to include the n8n object with links to the credentials and base node file. Update this file to include the following information:

{
	// All node names must start with "n8n-nodes-"
	"name": "n8n-nodes-friendgrid",
	"version": "0.1.0",
	"description": "n8n node to create contacts in SendGrid",
	"keywords": [
		// This keyword is required for community nodes
		"n8n-community-node-package"
	],
	"license": "MIT",
	"homepage": "https://n8n.io",
	"author": {
		"name": "Test",
		"email": "test@example.com"
	},
	"repository": {
		"type": "git",
		// Change the git remote to your own repository
		// Add the new URL here
		"url": "git+<your-repo-url>"
	},
	"main": "index.js",
	"scripts": {
		// don't change
	},
	"files": [
		"dist"
	],
	// Link the credentials and node
	"n8n": {
		"n8nNodesApiVersion": 1,
		"credentials": [
			"dist/credentials/FriendGridApi.credentials.js"
		],
		"nodes": [
			"dist/nodes/FriendGrid/FriendGrid.node.js"
		]
	},
	"devDependencies": {
		// don't change
	},
	"peerDependencies": {
		// don't change
	}
}

You need to update the package.json to include your own information, such as your name and repository URL. For more information on npm package.json files, refer to npm's package.json documentation.

Test your node

You can test your node as you build it by running it in a local n8n instance.

1. Install n8n using npm:

npm install n8n -g

2. When you are ready to test your node, publish it locally:

# In your node directory
npm run build
npm link

3. Install the node into your local n8n instance:

# In the nodes directory within your n8n installation
# node-package-name is the name from the package.json
npm link <node-package-name>

4. Start n8n:

n8n start

5. Open n8n in your browser. You should see your nodes when you search for them in the nodes panel.

   Node names

   Make sure you search using the node name, not the package name. For example, if your npm package name is n8n-nodes-weather-nodes, and the package contains nodes named rain, sun, snow, you should search for rain, not weather-nodes.

Troubleshooting

If there's no custom directory in ~/.n8n local installation, you have to create custom directory manually and run npm init:

# In ~/.n8n directory run
mkdir custom 
cd custom 
npm init

Next steps

• Deploy your node.
• View an example of a programmatic node: n8n's Mattermost node. This is an example of a more complex programmatic node structure.
• Learn about node versioning.
• Make sure you understand key concepts: item linking and data structures.