# Aggregate - Workflow node | Docs - nodulz

Source: https://nodulz.com/docs/nodes/aggregate

Language: en

Combine a field from many items into a list in a single item

## Usage and specifics

Use Aggregate to extract a field from each item and obtain one list of values. For a total or average, use [Summarize](/docs/nodes/summarize) instead.

With manual input `{ "contacts": [{ "email": "ada@example.test" }, { "email": "sam@example.test" }] }`, set `source` to `input.contacts`, `field` to `email`, `outputField` to `emails` and `operation` to `append`.

Expected output:

```json
{
  "emails": ["ada@example.test", "sam@example.test"],
  "count": 2
}
```

The result property name depends on `outputField`. With this configuration, use `{{ nodes.aggregate1.emails }}`, adapting the technical name; no `items` property is added automatically.

`append` preserves values in a list. `concat` converts them to text and joins them without a separator: here, the result would be `ada@example.testsam@example.test`. This mode does not flatten arrays or add a comma or newline. First check the format accepted by your destination.

Technical type : `aggregate`. Runtime : `nodulz`.

## Credentials and prerequisites

This node defines no dedicated external credential. Remote sources or execution targets may still need their own access credentials.

See the [credentials guide](/docs/credentials) if a remote source or execution target requires access.

## Parameters

Names below are technical keys. Defaults are not a ready-to-run configuration: complete fields required by your operation. Paths containing [] describe list items; some fields depend on the selected mode.

| Parameter | Type | Default | Values / limits |
| --- | --- | --- | --- |
| `source` | `string` | `""` | - |
| `field` | `string` | `""` | - |
| `outputField` | `string` | `"aggregated"` | - |
| `operation` | `enum` | `"append"` | `append`, `concat` |

## Initial configuration

Initial catalog configuration example, to adapt before running. Keep secrets in credentials.

```json
{
  "source": "",
  "field": "",
  "outputField": "aggregated",
  "operation": "append"
}
```

## Verification

Check the output field name, number of values and their type. With an empty source and `append`, expect an empty list and `count: 0`. Also test a contact without email: this node does not validate required fields, which should be checked upstream.

See also : [Expressions and data](/docs/expressions), [Executions](/docs/executions), [Node catalog](/docs/nodes).

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- [Features - nodulz](https://nodulz.com/product/overview)
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