# Set a board column's formula expression

Replaces the expression on a formula column of a custom board and recomputes its stored values. Needs manage access on the board; 404 for a column the board does not carry, 400 for an expression the evaluator rejects. Reach for it after previewing with POST /v1/formulas/preview, when the person has decided what the column should compute.

Access class: `board:manage`.

## Endpoint

`PUT /v1/boards/{id}/columns/{columnId}/formula`

## Parameters

| Name | In | Type | Required |
| --- | --- | --- | --- |
| id | path | string | Yes |
| columnId | path | string | Yes |

## Request body

Content type: `application/json`.

```json
{
  "body": {
    "expression": "string"
  },
  "params": {
    ":columnId": "",
    ":id": "string"
  },
  "query": {}
}
```

## Responses

### 200

the action's answer

Content type: `application/json`.

### default

a refusal: `{"error": "<what a person needs to read>"}`. 401 no credential, 402 the plan does not include this, 403 the seat does not, 404 the thing does not exist or is not yours to see.

Content type: `application/json`.

```json
{
  "error": "string"
}
```