n8n Workflow: Re-access Binary Data from Any Previous Node

This n8n workflow demonstrates a fundamental concept in n8n: how to re-access and utilize binary data that was generated by an earlier node in the workflow, even after subsequent nodes have processed or transformed the data. This is particularly useful when dealing with files, images, or other non-textual data that needs to be passed through multiple steps.

What it does

This workflow illustrates the process of handling binary data within n8n, specifically focusing on how to make binary data from a previous node available to a later node.

1. Manual Trigger: The workflow starts with a manual trigger, allowing you to execute it on demand.
2. HTTP Request: It then makes an HTTP GET request to a URL. While the specific URL is not provided in the JSON, this node is configured to return the response as binary data. This simulates fetching a file or image from an external source.
3. Edit Fields (Set): A "Set" node is included, which typically modifies or adds data to the workflow items. In this context, it serves to demonstrate that even after intermediate nodes, the original binary data can still be accessed.
4. Code Node: Finally, a Code node would typically contain custom JavaScript logic. This node is where you would implement the code to retrieve and process the binary data from the "HTTP Request" node.

Prerequisites/Requirements

• n8n Instance: You need a running n8n instance to import and execute this workflow.
• HTTP Endpoint (Optional): To fully test the "HTTP Request" node, you would ideally point it to an actual URL that returns binary data (e.g., an image URL, a PDF file URL).

Setup/Usage

1. Import the Workflow:
   • Copy the provided JSON code.
   • In your n8n instance, click "New" in the workflows section.
   • Click the three dots (...) in the top right corner and select "Import from JSON".
   • Paste the JSON code and click "Import".
2. Configure HTTP Request (Optional):
   • Click on the "HTTP Request" node.
   • In the "URL" field, enter the URL of a resource that returns binary data (e.g., https://www.n8n.io/favicon.ico for a small image).
   • Ensure the "Response Format" is set to "Binary Data" (this is the default when binaryData is true in the node's configuration).
3. Access Binary Data in Code Node:
   • Click on the "Code" node.
   • You can access the binary data from the "HTTP Request" node using an expression like {{ $node["HTTP Request"].binary.data }}. Replace data with the actual property name of the binary data if it's different.
   • For example, to log the binary data's name and size:

     const binaryData = $node["HTTP Request"].binary;
     if (binaryData && Object.keys(binaryData).length > 0) {
         const firstBinaryItem = binaryData[Object.keys(binaryData)[0]]; // Assuming one binary item
         console.log(`Binary data name: ${firstBinaryItem.fileName}`);
         console.log(`Binary data size: ${firstBinaryItem.fileSize} bytes`);
         // You can then process firstBinaryItem.data (which is a Buffer)
     }
     return items;
     

4. Execute the Workflow:
   • Click the "Execute Workflow" button in the "Manual Trigger" node or the "Execute Workflow" button in the n8n canvas toolbar.
   • Observe the output in the "Code" node to see the re-accessed binary data.