# operation-operationId-unique

Requires unique `operationId` values for each operation.

| OAS | Compatibility |
|  --- | --- |
| 2.0 | ✅ |
| 3.0 | ✅ |
| 3.1 | ✅ |


## API design principle

The `operationId` is used by tooling to identify operations (which are otherwise done through scary looking JSON pointers).

The `operationId` should be unique (used only once in an OpenAPI description).

This rule is unopinionated.

## Configuration

| Option | Type | Description |
|  --- | --- | --- |
| severity | string | Possible values: `off`, `warn`, `error`. Default `error` (in `recommended` configuration). |


An example configuration:


```yaml
rules:
  operation-operationId-unique: error
```

## Examples

Given this configuration:


```yaml
rules:
  operation-operationId-unique: error
```

Example of **incorrect** operations:


```yaml
paths:
  /cars:
    get:
      operationId: Car
      # ...
    post:
      operationId: Car
      # ...
```

Example of **correct** operations:


```yaml
paths:
  /cars:
    get:
      operationId: getCar
      # ...
    post:
      operationId: postCar
      # ...
```

## Related rules

- [operation-summary](/docs/cli/rules/oas/operation-summary)
- [operation-operationId-url-safe](/docs/cli/rules/oas/operation-operationId-url-safe)
- [operation-operationId](/docs/cli/rules/oas/operation-operationId)
- [configurable rules](/docs/cli/rules/configurable-rules)


## Resources

- [Rule source](https://github.com/Redocly/redocly-cli/blob/main/packages/core/src/rules/common/operation-operationId-unique.ts)
- [Operation object docs](https://redocly.com/docs/openapi-visual-reference/operation/)
- Consider using [configurable rules](/docs/cli/rules/configurable-rules) for more specific rules for `operationId`s such as length, casing, and pattern enforcement.