# POST /api/v1/counterparty-naming/rules

> Create a counterparty naming rule

- **Tag:** counterparty-naming
- **Operation ID:** `create_naming_rule`

## Description

When a new transaction's raw description (or detected name) matches ``pattern`` per ``match_type``, its counterparty is set to ``canonical_name``. Set ``apply_to_existing`` to rename matching history now (rows a person already edited are left alone).

## Authentication

Bearer token in `Authorization` header.
Required header: `x-business-id: <business uuid>`.

## Request body

Schema: `NamingRuleCreate`

- `pattern` (string · required)
- `match_type` (string) — contains | starts_with | exact | regex
- `canonical_name` (string · required)
- `priority` (integer)
- `is_enabled` (boolean)
- `apply_to_existing` (boolean) — Also rename existing matching transactions now (skips rows a person already edited).

## Responses

### 201 — Successful Response

Schema: `SuccessEnvelope_NamingRuleResponse_`

- `success` (boolean)
- `message` (string)
- `code` (string)
- `data` (NamingRuleResponse)

### 401 — Unauthorized - Missing/invalid token or no access to this business

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 403 — Forbidden - Insufficient permissions

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 422 — Validation Error

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

## Code samples

### cURL

```bash
curl -X POST 'https://api.ondayzero.com/api/v1/counterparty-naming/rules' \
  -H 'Authorization: Bearer dz_your_token' \
  -H 'x-business-id: YOUR_BUSINESS_ID' \
  -H 'Content-Type: application/json' \
  -d '{
  "pattern": "string",
  "canonical_name": "string"
}'
```

### JavaScript

```javascript
const response = await fetch('https://api.ondayzero.com/api/v1/counterparty-naming/rules', {
  method: 'POST',
  headers: {
    Authorization: 'Bearer dz_your_token',
    'x-business-id': 'YOUR_BUSINESS_ID',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
  "pattern": "string",
  "canonical_name": "string"
}),
});
const data = await response.json();
```

### Python

```python
import httpx

headers = {
    "Authorization": "Bearer dz_your_token",
    "x-business-id": "YOUR_BUSINESS_ID",
}

payload = {'pattern': 'string', 'canonical_name': 'string'}

response = httpx.post("https://api.ondayzero.com/api/v1/counterparty-naming/rules", headers=headers, json=payload)
data = response.json()
```

## See also

- HTML version: https://www.ondayzero.com/docs/reference/counterparty-naming/create-naming-rule
- OpenAPI slice: https://www.ondayzero.com/docs/reference/counterparty-naming/create-naming-rule/openapi.json
- Other endpoints in **counterparty-naming**: https://www.ondayzero.com/docs/reference/counterparty-naming (markdown bundle: https://www.ondayzero.com/docs/reference/counterparty-naming.md, OpenAPI: https://www.ondayzero.com/docs/reference/counterparty-naming/openapi.json)
- Endpoint catalog: https://www.ondayzero.com/docs/reference/index.md