Why Does One Binary Data Node Output Data While the Other Does Not?

Below is a general answer based on how node output behavior works in n8n. Keep in mind that without seeing the exact node configurations, my answer focuses on common reasons why one node might output data while another does not.

Potential Reasons for the Difference

1. Return Value Setup
   • In nodes built with the programmatic style, you must explicitly return an array of JSON objects from the execute() method (often using helpers like returnJsonArray). If this isn’t done, no data will be passed on.
   • In declarative-style nodes, output is often configured via the routing key under operations. A misconfiguration here (such as missing the routing details or having an incorrect HTTP method/URL) can lead to no output.

2. Node Mode (Execute Once vs. For Each Item)
   • If one node is set to “Execute Once” (via its settings tab) while the other processes all items individually, you might see output only in the one configured to iterate over incoming items.
   • Ensure that if your node should process multiple items, it isn’t inadvertently configured to run only once.

3. Data Handling Mechanism
   • Remember that nodes (especially when using the programmatic style) need to map and pass data correctly in their execution code. A missing or mis-assigned mapping (for example, neglecting to call Object.assign or failing to create the proper request options) can cause the node not to produce the expected output.

Steps to Troubleshoot

• Compare the Configuration:
  Look closely at the settings between the two nodes. For example, if the working (bottom) node explicitly returns output via a helper method (or has correct routing details in the declarative style), compare that with the non-working node to see if any step is missing.

• Review Node Settings (e.g. Execute Once):
  If the node that isn’t outputting data is meant to process multiple items, double-check that the “Execute Once” parameter isn’t enabled.

• Check Your Code (if using programmatic style):
  Make sure that your execute() method includes a return statement that maps the response data into an array format. For example, a typical snippet might look like:

  JSCopied
  async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
      // ... your processing logic
      const responseData = /* your transformed data */;
      return [this.helpers.returnJsonArray(responseData)];
  }

Conclusion

Even if two nodes seem very similar in purpose, differences in how they’re built (declarative vs. programmatic), configured (Execute Once setting), or how they handle data mapping and output returns can cause only one to produce data correctly.

Review the configuration, code (if applicable), and settings of both nodes. Comparing the working node with the one that isn’t outputting data should highlight where the difference lies.