n8n Nested Data Processing Loops with Sub-workflows

This n8n workflow demonstrates a powerful pattern for processing complex, nested data structures by leveraging sub-workflows and batch processing. It's designed to handle scenarios where you need to iterate over a primary list of items, and for each item, perform further operations that might involve iterating over a nested list.

What it does

This workflow showcases the following key concepts:

1. Manual Trigger: Initiates the workflow manually for testing and demonstration purposes.
2. Initial Data Setup (Edit Fields): Creates a sample dataset with a primary list of items, where each item contains a nested list of "subItems". This simulates a common real-world data structure.
3. Outer Loop (Loop Over Items): Iterates over the primary list of items, processing them in batches. This is the "outer" loop of the nested processing.
4. Execute Sub-workflow: For each item in the outer loop, it calls a separate sub-workflow. This sub-workflow is responsible for processing the nested data within that item.
5. Sub-workflow Trigger (When Executed by Another Workflow): The sub-workflow starts when it's called by the main workflow.
6. Sub-workflow Data Processing (Code Node): Within the sub-workflow, a Code node simulates processing the nested "subItems" for the current item. This could involve further API calls, data transformations, or database operations.
7. Sticky Notes: Provides inline documentation and explanations for different parts of the workflow.

Prerequisites/Requirements

• n8n Instance: An active n8n instance (self-hosted or cloud).
• Understanding of n8n Workflows: Basic familiarity with building and executing n8n workflows.

Setup/Usage

1. Import the Workflow:
   • Copy the provided JSON code.
   • In your n8n instance, go to "Workflows" and click "New".
   • Click the three dots (...) next to the workflow name and select "Import from JSON".
   • Paste the JSON code and click "Import".
2. Activate the Workflow: Ensure the workflow is active by toggling the "Active" switch in the top right corner.
3. Execute the Workflow: Click "Execute Workflow" to run the workflow manually and observe its behavior. You can inspect the data flowing through each node to understand the nested loop processing.
4. Explore the Sub-workflow: The "Execute Sub-workflow" node references a sub-workflow. You would typically create this sub-workflow separately. While this example does not include the JSON for the sub-workflow, the Execute Workflow Trigger and Code nodes within the main workflow JSON imply its structure. The sub-workflow would start with an Execute Workflow Trigger and then contain the logic to process the nested data it receives.

This workflow provides a robust template for handling complex data processing tasks that require iterating through multiple levels of data.