How to Iterate Over Array Values from a Query in n8n?

Below is one approach that most users have found to be both simple and effective:

1. Restructure your incoming data into separate items

n8n automatically iterates through items if each value comes as its own item. If your incoming query contains an array (for example, an array of Slack user IDs), you can use a node to “split” the data so that each value is on its own item. For instance, if your query is part of the JSON data as an array, you can use the built-in iteration model by ensuring your previous node outputs a list where each item contains one Slack user ID.

If your query data looks like this:

JSONCopied
{
  "query": {
    "username": ["user1", "user2", "user3", "user4", "user5", "user6", "user7"]
  }
}

You can then use a Code node (or any node that supports item-by-item processing) set to “Run Once for Each Item.” To do this you could first use a JMESPath expression to extract the array – for example:

JSCopied
{{$jmespath($json.query, "username")}}

Then, use a Split In Batches or another mechanism (like a Function node that creates a separate item per array element) so that the Tool node receives each Slack user ID as its own item. When the Tool node is executed in “Run Once for Each Item” mode, it will process each value individually.

2. Use JMESPath for direct extraction (if structure is correct)

If your incoming data is already individual items, you can use a JMESPath projection in an expression to iterate over the values. For example, if you want to extract all usernames:

JSCopied
{{$jmespath($json.query, "[*]")}}

This expression tells n8n to project over the array. Make sure of the following:

• The property names in your JSON are correct. (If using username returns undefined, check that your JSON actually has that key inside query.)
• If the key isn’t exactly username or if it’s nested more deeply, adjust the path accordingly. You can view the JSON output of your previous node (using a Set or Code node) to confirm the structure.

3. About the $fromAI() behavior

Keep in mind that the $fromAI() function is not designed to iterate over an array on its own. When you use:

JSCopied
{{ $fromAI("slackuserid", "next slackuserid") }}

the function uses the provided key as an input hint for the AI model. It’s not inherently set up to pick a different element for each of multiple incoming items—resulting in the same value being sent for every item.

Summary

The easiest approach is to ensure that your worksheet (or the previous node output) is formatted as an array with one Slack user ID per item. Then, by using nodes that run once per item (or by splitting the array into individual items), you let n8n handle the iteration for you. This avoids the need for complex loop nodes on the Tools Agent (which, as you mentioned, are not supported).

In short:

• Verify and adjust your JSON structure so that each value is in its own item.
• Use a JMESPath expression to extract the array, ensuring you reference the correct key(s).
• Process each value individually by allowing n8n to automatically iterate through multiple items.

This pattern is simple, leverages n8n’s built-in iteration, and avoids issues with using $fromAI() for handling multiple values.