Basics

• All data passed between nodes is an array of objects
• To manipulate data, n8n needs this data structure:

[items array: {json:obj}, {json:obj}, {json:obj}]

• But often our data will be in the format:

[items array: [ json array: {obj}, {obj}, {obj} ] ]

• Each n8n node runs its operations on  in the array

  each item

• So in the first data structure it operates 3 times on {json:obj}

• But in the second data structure it operates just once on the json array.

Unbundling

When you have the second type of data structure, you need to:

1. First unbundle the json array into items

2. Then run operations on each individual item.

To do this, use a function node:

return items[0].json.map( item => ( { json : item } ));

Nested Items

Sometimes (e.g. with external APIs returning data in a different format), you will encounter nested items. This usually means the data we are interested in is its own object nested within the JSON response from the API.

Where "results" is the object/array of interest, we would modify our function above as so:

return items[0].json.results.map(item => ( { json : item } ));

Recap