Aggregate

Node type: aggregate · Version: 1 · Category: Data Reduce collection items into one deterministic result. This node is not marked with the catalogue’s generic side-effect flag. That classification is not a guarantee that every configured operation is read-only; review the concrete action and its destination.

When to use this node

Reduce several items to a count, numeric value, string, group, object or collected array.
Create a single report value after a loop.

Example: Count processed rows

Count all completed items after collection processing.

Example settings

{
  "operation": "count",
  "fieldPath": "",
  "includeMissing": false
}

This shows the important settings, not a complete exported node. Local paths must be selected, mapped from a trusted path, or covered by the runner’s approved boundary.

Connect a collection-producing node.
Choose an operation and only its relevant fields.
Inspect the aggregate preview and source count.

Configuration

Field	Type	Default	What it controls
`operation`	string	`"collect_items"`	Reduction performed over the input collection. Values: `collect_items`, `collect_field`, `count`, `sum`, `minimum`, `maximum`, `average`, `first`, `last`, `concatenate`, `group_by`, `object_by_key`.
`fieldPath`	string	`""`	Selected item field for field-based operations.
`includeMissing`	boolean	`false`	Represent missing selections deliberately.
`preserveLineage`	boolean	`false`	Retain bounded source item identifiers in result evidence.
`separator`	string	`","`	Separator for string concatenation.
`groupFields`	array	`[]`	Ordered fields forming a deterministic group key.
`keyField`	string	`"id"`	Field used as an object property key.
`duplicateKeyPolicy`	string	`"fail"`	Explicit duplicate object-key behavior. Values: `fail`, `keep_first`, `keep_last`.

Workflow JSON

The editor stores this node with the following implemented default configuration:

Default node configuration

{
  "type": "aggregate",
  "version": 1,
  "configuration": {
    "operation": "collect_items",
    "fieldPath": "",
    "includeMissing": false,
    "preserveLineage": false,
    "separator": ",",
    "groupFields": [],
    "keyField": "id",
    "duplicateKeyPolicy": "fail"
  }
}

Values may be entered literally or mapped from an earlier compatible output when the inspector exposes a mapping control. See Variables and data mapping.

Inputs

Port	Type	Required	Description
`items`	`array`	Yes	Items

Outputs

Port	Type	Required	Description
`value`	`any`	No	Aggregate

Execution behavior

Numeric operations reject strings rather than coercing them.
Results are deterministic in input order and bounded by aggregate byte policy.
The editor catalogue declares value (any) for mapping. The execution inspector can contain additional evidence fields; inspect a real result before selecting nested paths from object or any outputs.

Common issues

Empty numeric selections return null; count returns zero.
Object-by-key requires an explicit duplicate-key policy.

Where it can run

Desktop local runner
Paired self-hosted runner
Hosted runner

Test and inspect

Use Test node in the editor to preview this step with the current configuration. A full run records resolved inputs, outputs, logs, duration, and any artifacts in the execution inspector. Side-effecting or destructive nodes can require an additional confirmation or approved workflow permission.

Node reference

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Data

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System

When to use this node

Example: Count processed rows

Configuration

Workflow JSON

Inputs

Outputs

Execution behavior

Common issues

Where it can run

Test and inspect

​When to use this node

​Example: Count processed rows

​Configuration

​Workflow JSON

​Inputs

​Outputs

​Execution behavior

​Common issues

​Where it can run

​Test and inspect

​Related guides

When to use this node

Example: Count processed rows

Configuration

Workflow JSON

Inputs

Outputs

Execution behavior

Common issues

Where it can run

Test and inspect

Related guides