| --- |
| |
| contentType: explanation |
| --- |
| |
| # Choose your node building approach |
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| n8n has two node-building styles, declarative and programmatic. |
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| You should use the declarative style for most nodes. This style: |
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| * Uses a JSON-based syntax, making it simpler to write, with less risk of introducing bugs. |
| * Is more future-proof. |
| * Supports integration with REST APIs. |
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| The programmatic style is more verbose. You must use the programmatic style for: |
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| * Trigger nodes |
| * Any node that isn't REST-based. This includes nodes that need to call a GraphQL API and nodes that use external dependencies. |
| * Any node that needs to transform incoming data. |
| * Full versioning. Refer to [Node versioning](/integrations/creating-nodes/build/reference/node-versioning.md) for more information on types of versioning. |
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| ## Data handling differences |
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| The main difference between the declarative and programmatic styles is how they handle incoming data and build API requests. The programmatic style requires an `execute()` method, which reads incoming data and parameters, then builds a request. The declarative style handles this using the `routing` key in the `operations` object. Refer to [Node base file](/integrations/creating-nodes/build/reference/node-base-files/index.md) for more information on node parameters and the `execute()` method. |
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| ## Syntax differences |
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| To understand the difference between the declarative and programmatic styles, compare the two code snippets below. This example creates a simplified version of the SendGrid integration, called "FriendGrid." The following code snippets aren't complete: they emphasize the differences in the node building styles. |
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| In programmatic style: |
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| ```js |
| import { |
| IExecuteFunctions, |
| INodeExecutionData, |
| INodeType, |
| INodeTypeDescription, |
| IRequestOptions, |
| } from 'n8n-workflow'; |
| |
| // Create the FriendGrid class |
| export class FriendGrid implements INodeType { |
| description: INodeTypeDescription = { |
| displayName: 'FriendGrid', |
| name: 'friendGrid', |
| . . . |
| properties: [ |
| { |
| displayName: 'Resource', |
| . . . |
| }, |
| { |
| displayName: 'Operation', |
| name: 'operation', |
| type: 'options', |
| displayOptions: { |
| show: { |
| resource: [ |
| 'contact', |
| ], |
| }, |
| }, |
| options: [ |
| { |
| name: 'Create', |
| value: 'create', |
| description: 'Create a contact', |
| }, |
| ], |
| default: 'create', |
| description: 'The operation to perform.', |
| }, |
| { |
| displayName: 'Email', |
| name: 'email', |
| . . . |
| }, |
| { |
| displayName: 'Additional Fields', |
| // Sets up optional fields |
| }, |
| ], |
| }; |
| |
| async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> { |
| let responseData; |
| const resource = this.getNodeParameter('resource', 0) as string; |
| const operation = this.getNodeParameter('operation', 0) as string; |
| //Get credentials the user provided for this node |
| const credentials = await this.getCredentials('friendGridApi') as IDataObject; |
| |
| if (resource === 'contact') { |
| if (operation === 'create') { |
| // Get email input |
| const email = this.getNodeParameter('email', 0) as string; |
| // Get additional fields input |
| const additionalFields = this.getNodeParameter('additionalFields', 0) as IDataObject; |
| const data: IDataObject = { |
| email, |
| }; |
| |
| Object.assign(data, additionalFields); |
| |
| // Make HTTP request as defined in https://sendgrid.com/docs/api-reference/ |
| const options: IRequestOptions = { |
| headers: { |
| 'Accept': 'application/json', |
| 'Authorization': `Bearer ${credentials.apiKey}`, |
| }, |
| method: 'PUT', |
| body: { |
| contacts: [ |
| data, |
| ], |
| }, |
| url: `https://api.sendgrid.com/v3/marketing/contacts`, |
| json: true, |
| }; |
| responseData = await this.helpers.httpRequest(options); |
| } |
| } |
| // Map data to n8n data |
| return [this.helpers.returnJsonArray(responseData)]; |
| } |
| } |
| ``` |
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| In declarative style: |
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| ```js |
| import { INodeType, INodeTypeDescription } from 'n8n-workflow'; |
| |
| // Create the FriendGrid class |
| export class FriendGrid implements INodeType { |
| description: INodeTypeDescription = { |
| displayName: 'FriendGrid', |
| name: 'friendGrid', |
| . . . |
| // Set up the basic request configuration |
| requestDefaults: { |
| baseURL: 'https://api.sendgrid.com/v3/marketing' |
| }, |
| properties: [ |
| { |
| displayName: 'Resource', |
| . . . |
| }, |
| { |
| displayName: 'Operation', |
| name: 'operation', |
| type: 'options', |
| displayOptions: { |
| show: { |
| resource: [ |
| 'contact', |
| ], |
| }, |
| }, |
| options: [ |
| { |
| name: 'Create', |
| value: 'create', |
| description: 'Create a contact', |
| // Add the routing object |
| routing: { |
| request: { |
| method: 'POST', |
| url: '=/contacts', |
| send: { |
| type: 'body', |
| properties: { |
| email: {{$parameter["email"]}} |
| } |
| } |
| } |
| }, |
| // Handle the response to contact creation |
| output: { |
| postReceive: [ |
| { |
| type: 'set', |
| properties: { |
| value: '={{ { "success": $response } }}' |
| } |
| } |
| ] |
| } |
| }, |
| ], |
| default: 'create', |
| description: 'The operation to perform.', |
| }, |
| { |
| displayName: 'Email', |
| . . . |
| }, |
| { |
| displayName: 'Additional Fields', |
| // Sets up optional fields |
| }, |
| ], |
| } |
| // No execute method needed |
| } |
| ``` |
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