# path-parameters-defined

Source: https://apigenie.pl/docs/linter/swagger/rules/path-parameters-defined

This rule checks whether every parameter of a path template is declared as a
path parameter.

## Rule Details

The Swagger 2.0 specification requires every template expression of a path
(such as `{userId}` in `/users/{userId}`) to correspond to a parameter with
`in: path`. Without it, tools do not know the type of the parameter and cannot
build request URLs.

The `path-parameters-defined` rule checks every operation and reports `One or
more path parameters are missing` when a template expression of its path has
no matching `in: path` parameter, either among the parameters of the path item
or among the parameters of the operation. Parameter references (`$ref`) are
resolved; a parameter with the right name in another location (for example
`in: query`) does not count. Path parameters that do not appear in the
template are not reported.

## Configuration

The options are an object with an optional `defaultType` property, which sets
the `type` of the parameters added by the automatic fix: `string` (default),
`integer`, `number` or `boolean`. Set it to `null` to disable the automatic
fix.

```yaml
commands:
  lint:
    swagger:
      rules:
        path-parameters-defined:
          - error
          - defaultType: integer
```

## Examples

**Good**. The path parameter is declared on the path item.

```yaml
swagger: '2.0'
info:
  title: Users
  version: 1.0.0
paths:
  /users/{userId}:
    parameters:
      - name: userId
        in: path
        required: true
        type: string
    get:
      responses:
        '200':
          description: A single user.
    delete:
      responses:
        '204':
          description: The user was deleted.
```

**Bad**. The `get` operation declares `userId` as a query parameter and the
`delete` operation does not declare it at all.

```yaml
swagger: '2.0'
info:
  title: Users
  version: 1.0.0
paths:
  /users/{userId}:
    get:
      parameters:
        - name: userId
          in: query
          type: string
      responses:
        '200':
          description: A single user.
    delete:
      responses:
        '204':
          description: The user was deleted.
```

## Automatic fixes

When invoked with `--fix`, this rule appends the missing parameters, in the
order they appear in the path template, to the `parameters` of the path item.
Each added parameter has the form `{name: <name>, in: path, required: true,
type: <defaultType>}`. No fix is offered when `defaultType` is `null`.

## When Not to Use It

We recommend to always enable this rule, since undeclared path parameters
violate the Swagger 2.0 specification.

## Compatibility

This rule is compatible with Swagger 2.0 documents. OpenAPI 3.x documents are
linted by the OpenAPI linter, which has a rule of the same name.