# POST Validate customiser settings

Dry-run a settings merge patch without persisting anything. The request body is the same merge patch the update operation accepts, and the response is exactly what that update would produce on the failing paths: the identical 422 problem (`validation_failed` with pointers and `allowed_values`, or `unknown_field`) — the same validation code path runs, only persistence is skipped. On a patch that would apply, the response is a 200 `customiser_settings_validation` confirmation. Nothing is written, no caches are touched, no idempotency key is consumed, and no activity is recorded, so the operation is always safe to repeat. The verdict is advisory: nothing binds it to a later update, and the settings can legitimately change between the two calls. Requires the `customisers:write` scope (it is the write's dry-run twin). A 400 problem means the body is not valid JSON; a 422 problem with code `invalid_document` means the body is not a JSON object. 401/403/404/429 behave as on the read operation, with `customisers:write` as the required scope.

- Source URL: https://www.signcustomiser.com/help/api/v3-post-validate-customiser-settings/
- Markdown URL: https://www.signcustomiser.com/help/api/v3-post-validate-customiser-settings.md
- Group: Customiser settings
- Method: POST
- Path: /api/v3/customisers/{customiser_id}/settings/validate-update
- Auth: Bearer token
- Required scopes: `customisers:write`

## Path parameters

- customiser_id (string, required): The customiser id, from the list customisers operation. Example: 1

## Body parameters

- custom_sizing (boolean, optional): No description provided.

## Request body example

```json
{
  "custom_sizing": true
}
```

## cURL example

```bash
curl https://web.signcustomiser.com/api/v3/customisers/1/settings/validate-update \
  --request POST \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer YOUR_API_TOKEN' \
  --header 'Content-Type: application/json' \
  --data '{
  "custom_sizing": true
}'
```

## Response examples

### 200 Patch would apply

```json
{
  "data": {
    "object": "customiser_settings_validation",
    "operation": "update",
    "customiser_id": 42,
    "valid": true
  },
  "links": {
    "self": "https://web.signcustomiser.com/api/v3/customisers/42/settings/validate-update",
    "documentation": "https://www.signcustomiser.com/help/api/"
  },
  "meta": {
    "api_version": "v3",
    "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
  }
}
```

### 400 Malformed JSON body

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/malformed_json",
  "title": "Malformed JSON",
  "status": 400,
  "code": "malformed_json",
  "detail": "The request body is not valid JSON: Syntax error.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 401 Missing API key

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/missing_api_key",
  "title": "Missing API key",
  "status": 401,
  "code": "missing_api_key",
  "detail": "Provide a store API key as a bearer token: Authorization: Bearer <api key>. Keys are created in the merchant admin under Integrate → API Tokens.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 403 Insufficient scope

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/insufficient_scope",
  "title": "Insufficient scope",
  "status": 403,
  "code": "insufficient_scope",
  "detail": "This operation requires the customisers:write scope, but the API key grants the following scopes: customisers:read. Create a key that includes the required scope in the merchant admin under Integrate → API Tokens.",
  "required_scopes": [
    "customisers:write"
  ],
  "granted_scopes": [
    "customisers:read"
  ],
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 404 Unknown customiser

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/resource_not_found",
  "title": "Resource not found",
  "status": 404,
  "code": "resource_not_found",
  "detail": "The requested resource does not exist or does not belong to the authenticated store.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 422 Validation failed

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/validation_failed",
  "title": "Validation failed",
  "status": 422,
  "code": "validation_failed",
  "detail": "The request payload failed validation. Correct the fields listed in errors and retry.",
  "errors": [
    {
      "pointer": "/measurement_unit",
      "code": "unsupported_value",
      "detail": "The selected measurement unit is invalid.",
      "allowed_values": [
        "both",
        "centimetres",
        "inches"
      ]
    }
  ],
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 429 Rate limited

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/rate_limited",
  "title": "Too many requests",
  "status": 429,
  "code": "rate_limited",
  "detail": "You have exceeded the request limit for this API key. Wait 60 seconds, then retry.",
  "retry_after": 60,
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```