8.3 KiB
Nodes
Function and Function Item Nodes
These are the most powerful nodes in n8n. With these, almost everything can be done if you know how to write JavaScript code. Both nodes work very similarly. They give you access to the incoming data and you can manipulate it.
Difference between both nodes
The difference is that the code of the Function node gets executed only once. It receives the full items (JSON and binary data) as an array and expects an array of items as a return value. The items returned can be totally different from the incoming ones. So it is not only possible to remove and edit existing items, but also to add or return totally new ones.
The code of the Function Item node on the other hand gets executed once for every item. It receives
one item at a time as input and also just the JSON data. As a return value, it expects the JSON data
of one single item. That makes it possible to add, remove and edit JSON properties of items
but it is not possible to add new or remove existing items. Accessing and changing binary data is only
possible via the methods getBinaryData and setBinaryData.
Both nodes support promises. So instead of returning the item or items directly, it is also possible to return a promise which resolves accordingly.
Function-Node
Variable: items
It contains all the items that the node received as input.
Information about how the data is structured can be found on the page Data Structure.
The data can be accessed and manipulated like this:
// Sets the JSON data property "myFileName" of the first item to the name of the
// file which is set in the binary property "image" of the same item.
items[0].json.myFileName = items[0].binary.image.fileName;
return items;
This example creates 10 dummy items with the ids 0 to 9:
const newItems = [];
for (let i=0;i<10;i++) {
newItems.push({
json: {
id: i
}
});
}
return newItems;
Method: $item(index: number, runIndex?: number)
With $item it is possible to access the data of parent nodes. That can be the item data but also
the parameters. It expects as input an index of the item the data should be returned for. This is
needed because for each item the data returned can be different. This is probably obvious for the
item data itself but maybe less for data like parameters. The reason why it is also needed, is
that they may contain an expression. Expressions get always executed of the context for an item.
If that would not be the case, for example, the Email Send node not would be able to send multiple
emails at once to different people. Instead, the same person would receive multiple emails.
The index is 0 based. So $item(0) will return the first item, $item(1) the second one, ...
By default the item of the last run of the node will be returned. So if the referenced node ran 3x (its last runIndex is 2) and the current node runs the first time (its runIndex is 0) the data of runIndex 2 of the referenced node will be returned.
For more information about what data can be accessed via $node, check here.
Example:
// Returns the value of the JSON data property "myNumber" of Node "Set" (first item)
const myNumber = $item(0).$node["Set"].json["myNumber"];
// Like above but data of the 6th item
const myNumber = $item(5).$node["Set"].json["myNumber"];
// Returns the value of the parameter "channel" of Node "Slack".
// If it contains an expression the value will be resolved with the
// data of the first item.
const channel = $item(0).$node["Slack"].parameter["channel"];
// Like above but resolved with the value of the 10th item.
const channel = $item(9).$node["Slack"].parameter["channel"];
Method: $items(nodeName?: string, outputIndex?: number, runIndex?: number)
Gives access to all the items of current or parent nodes. If no parameters get supplied, it returns all the items of the current node. If a node-name is given, it returns the items the node output on its first output (index: 0, most nodes only have one output, exceptions are IF and Switch-Node) on its last run.
Example:
// Returns all the items of the current node and current run
const allItems = $items();
// Returns all items the node "IF" outputs (index: 0 which is Output "true" of its most recent run)
const allItems = $items("IF");
// Returns all items the node "IF" outputs (index: 0 which is Output "true" of the same run as current node)
const allItems = $items("IF", 0, $runIndex);
// Returns all items the node "IF" outputs (index: 1 which is Output "false" of run 0 which is the first run)
const allItems = $items("IF", 1, 0);
Variable: $node
Works exactly like $item with the difference that it will always return the data of the first item and
the last run of the node.
// Returns the fileName of binary property "data" of Node "HTTP Request"
const fileName = $node["HTTP Request"].binary["data"]["fileName"]}}
// Returns the context data "noItemsLeft" of Node "SplitInBatches"
const noItemsLeft = $node["SplitInBatches"].context["noItemsLeft"];
// Returns the value of the JSON data property "myNumber" of Node "Set"
const myNumber = $node["Set"].json['myNumber'];
// Returns the value of the parameter "channel" of Node "Slack"
const channel = $node["Slack"].parameter["channel"];
// Returns the index of the last run of Node "HTTP Request"
const runIndex = $node["HTTP Request"].runIndex}}
Variable: $runIndex
Contains the index of the current run of the node.
// Returns all items the node "IF" outputs (index: 0 which is Output "true" of the same run as current node)
const allItems = $items("IF", 0, $runIndex);
Variable: $workflow
Gives information about the current workflow.
const isActive = $workflow.active;
const workflowId = $workflow.id;
const workflowName = $workflow.name;
Method: $evaluateExpression(expression: string, itemIndex: number)
Evaluates a given string as expression.
If no itemIndex is provided it uses by default in the Function-Node the data of item 0 and
in the Function Item-Node the data of the current item.
Example:
items[0].json.variable1 = $evaluateExpression('{{1+2}}');
items[0].json.variable2 = $evaluateExpression($node["Set"].json["myExpression"], 1);
return items;
Method: getWorkflowStaticData(type)
Gives access to the static workflow data. It is possible to save data directly with the workflow. This data should, however, be very small. A common use case is to for example to save a timestamp of the last item that got processed from an RSS-Feed or database. It will always return an object. Properties can then read, delete or set on that object. When the workflow execution succeeds, n8n will check automatically if the data has changed and will save it, if necessary.
There are two types of static data. The "global" and the "node" one. Global static data is the same in the whole workflow. And every node in the workflow can access it. The node static data , however, is different for every node and only the node which set it can retrieve it again.
Example:
// Get the global workflow static data
const staticData = getWorkflowStaticData('global');
// Get the static data of the node
const staticData = getWorkflowStaticData('node');
// Access its data
const lastExecution = staticData.lastExecution;
// Update its data
staticData.lastExecution = new Date().getTime();
// Delete data
delete staticData.lastExecution;
It is important to know that the static data can not be read and written when testing via the UI. The data there will always be empty and the changes will not persist. Only when a workflow is active and it gets called by a Trigger or Webhook, the static data will be saved.
Function Item-Node
Variable: item
It contains the "json" data of the currently processed item.
The data can be accessed and manipulated like this:
// Uses the data of an already existing key to create a new additional one
item.newIncrementedCounter = item.existingCounter + 1;
return item;
Method: getBinaryData()
Returns all the binary data (all keys) of the item which gets currently processed.
Method: setBinaryData(binaryData)
Sets all the binary data (all keys) of the item which gets currently processed.
Method: getWorkflowStaticData(type)
As described above for Function node.