Troubleshooting Binary Data Extraction from PDF Email Attachments

Below is a checklist of things to verify and adjust in your workflow when extracting binary data from a PDF attachment sent via Gmail:

1. Confirm Gmail Node Configuration

• Attachment Handling: Make sure that your Gmail node is set up to download attachments. The node should pass the PDF as binary data in a property (typically named "data" by default).
• Property Name: Check which binary property is used. If it’s not “data,” update the following nodes (like Extract From File) accordingly.

2. Use the Correct Processing Node

• Extract From File Node: After receiving the PDF, use the Extract From File node to convert the binary data to JSON. In its settings, ensure the binary property name matches what comes from the Gmail node.

• Alternative with Code: If you need to inspect or manipulate the binary data programmatically, consider adding a Code node and using n8n’s helpers function:

  JSCopied
  // Replace 'data' with the actual binary property if different
  let binaryDataBuffer = await this.helpers.getBinaryDataBuffer(0, 'data');
  // Now you can process your buffer as needed

3. Verify the Workflow Order

• Flow Sequence: Make sure the output of the Gmail node feeds directly into the node that processes the binary data (e.g., Extract From File or a Code node).
• Debugging: You can add a Code node before extraction to output the keys present in your binary object. This can help you verify the correct binary property name.

4. Environment & Runtime Considerations

• Self-Hosted vs. n8n Cloud: If you’re on n8n Cloud, remember that nodes like Read/Write Files from Disk are not available. This mostly affects file operations but is worthwhile to keep in mind for binary workflows.
• Memory vs. Filesystem Mode: For large PDF files, check if you need to adjust your binary data mode (using N8N_DEFAULT_BINARY_DATA_MODE) to avoid memory issues.

By ensuring the Gmail node is correctly returning the binary data under the correct property name and that the subsequent node references that same property, you should be able to extract the information successfully. Feel free to further inspect the binary data using the Code node if you’re still having issues.

If you continue to experience problems, double-check your node configurations and consider adding intermediate debugging steps to inspect the structure of the data flowing through your workflow.