How can I manage undefined resource IDs in n8n sub-run workflows using an IF node?

Below is an approach you can use to avoid the error when an expected file ID is missing in later runs:

1. Persist the File IDs
   When you create your Google Workspace files on the first run, store the file IDs somewhere for future reference. One way is to use a SET node (or write them to an external database or file) so that subsequent runs can pick up the correct IDs instead of having them become undefined.

2. Conditionally Update Only When an ID Exists
   Before running your update nodes for Docs (or Sheets and Drive folders), add an IF (or similar) node that checks whether the file ID exists. For example, you can create a condition like:

   JSCopied
   {{ $json.id !== undefined && $json.id !== '' }}

   This way the update operation is only attempted when the file ID is present, and otherwise you can bypass the update step.

3. Use the SET Node to Inject the Persisted ID
   In your branch for subsequent runs, use a SET node to reassign the file ID from your stored value. For instance, if you have stored the file ID in a variable or external storage, your SET node can create the JSON structure with that ID:

   JSONCopied
   {
     "id": "YOUR_STORED_FILE_ID"
   }

   Then, downstream, the update node will receive a valid file ID and will not trigger the “resource not found” error.

4. Evaluate Your Workflow Structure
   Double-check that your workflow doesn’t end up skipping the nodes that provide the needed outputs. The error message indicates that the update node is receiving an undefined ID because the node producing the file ID isn’t executed. Using persistence with a SET node or conditional check avoids this scenario.

By keeping track of the created file IDs and using conditional logic to only attempt updates when appropriate, you can bypass the error during subsequent runs. This approach is in line with best practices for handling scenarios where some nodes may not execute (for instance, when the creation step is skipped in later runs).

Give this structure a try in your Docker-based setup, and it should prevent the update operations from failing due to missing IDs.