# Map

> Reshape each entry of a list, for example by renaming or combining its fields.

Transforms each entry in a collection by modifying or reshaping its fields.

## Configuration

| Field | Required | Description |
|---|---|---|
| **Input** | Yes | The collection (array) to transform. |
| **Field mappings** | Yes | For each target field, define the name and the source field or expression. |

## Example

Rename `firstName` and `lastName` fields to `first` and `last`:

| Target field | Source mapping |
|---|---|
| `first` | `firstName` |
| `last` | `lastName` |

Output available as `$vars.map1.output`.

## Common issues

| Issue | Resolution |
|---|---|
| Output has `undefined` fields | The source field doesn't exist in the input entries. Use the execution trace to confirm the input structure. |

## Next steps

- [Transform](node-transform.md): chain several operations in one node.
- [Script](node-script.md): custom logic when no data operation fits.