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Data structure#

In n8n, all data passed between nodes is an array of objects. It has the following structure:

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[
	{
		// For most data:
		// Wrap each item in another object, with the key 'json'
		"json": {
			// Example data
			"apple": "beets",
			"carrot": {
				"dill": 1
			}
		},
		// For binary data:
		// Wrap each item in another object, with the key 'binary'
		"binary": {
			// Example data
			"apple-picture": {
				"data": "....", // Base64 encoded binary data (required)
				"mimeType": "image/png", // Best practice to set if possible (optional)
				"fileExtension": "png", // Best practice to set if possible (optional)
				"fileName": "example.png", // Best practice to set if possible (optional)
			}
		}
	},
]

Skipping the json key and array syntax

From 0.166.0 on, when using the Function node or Code node, n8n automatically adds the json key if it's missing. It also automatically wraps your items in an array ([]) if needed. This is only the case when using the Function or Code nodes. When building your own nodes, you must still make sure the node returns data with the json key.

Data item processing#

Nodes can process multiple items.

For example, if you set the Trello node to Create-Card, and create an expression that sets Name using a property called name-input-value from the incoming data, the node creates a card for each item, always choosing the name-input-value of the current item.

For example, this input will create two cards. One named test1 the other one named test2:

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[
	{
		name-input-value: "test1"
	},
	{
		name-input-value: "test2"
	}
]
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