# Update link between layers
<!-- <div class="algorithm-id">
<strong>Algorithm ID</strong>: <code>hedgetools:updaterelation</code>
</div> -->
```{container} algorithm-id
**Algorithm ID**: `hedgetools:updaterelation`
```

 This tool takes a polygon, line, and point layer — typically generated at the end of the [Data - Preparation](./data_preparation/index.md) or [Data - Transformation](./data_transformation/index.md) steps — and updates the fields that allow geometries to be associated across layers.

It is useful when the topology has been disrupted due to manipulations or error corrections.

## Parameters

| Label | Name | Type | Description |
|----------|----------|----------|----------|
| Input polygon layer | `INPUT_POLY`| [vector: polygon] | Input polygon vector layer |
| Input arc layer | `INPUT_ARC`| [vector: line] | Input line vector layer |
| Input node layer | `INPUT_NODE`| [vector: point] | Input node vector layer |
| Output polygon layer | `OUTPUT_POLY`| [vector: polygon] <br> Default: `[Create temporary layer]` | Output polygon vector layer |
| Output arc layer | `OUTPUT_ARC`| [vector: line] <br> Default: `[Create temporary layer]` | Output line vector layer |
| Output node layer | `OUTPUT_NODE`| [vector: point] <br> Default: `[Create temporary layer]` | Output node vector layer |

## Outputs

| Label         | Name          | Type           | Description |
|---------------|---------------|----------------|-------------|
| Output polygon layer | `OUTPUT_POLY` | [vector: polygon] | The output polygon vector layer will have updated following link fields:<ul><li>`pid`: primary key of the polygon</li></ul> |
| Output arc layer     | `OUTPUT_ARC`  | [vector: line]  | The output line vector layer will have updated following link fields:<ul><li>`pid`: foreign key referencing the polygon</li><li>`eid`: primary key of the line</li><li>`src_vid`: foreign key of one of the nodes at the line’s extremities</li><li>`tgt_vid`: foreign key of the other node at the line’s extremities</li></ul> |
| Output node layer    | `OUTPUT_NODE` | [vector: point] | The output polygon vector layer will have updated following link fields:<ul><li>`vid`: primary key of the node</li></ul> |