# schema-format-type-mismatch

Source: https://apigenie.pl/docs/linter/swagger/rules/schema-format-type-mismatch

This rule ensures that the `format` of an object is one that applies to its
`type`.

## Rule Details

Each well-known format applies to a single type. A format paired with another
type (e.g. `type: integer` with `format: date-time`) is contradictory, and
tools interpret it inconsistently.

The `schema-format-type-mismatch` rule checks every object of a Swagger 2.0
document that has a `format`: schemas, non-body parameters, response headers
and `items` objects (objects with a `$ref` are checked where they are
defined). It checks the formats Swagger 2.0 defines and the JSON Schema ones it
allows, with the JSON types the
[OpenAPI format registry](https://spec.openapis.org/registry/format/) gives
them, and the formats of `openapi.custom_formats` in the configuration file:

- `int32`, `int64` - `integer` or `number`, and `string` for `int64`,
- `float`, `double` - `number`,
- `byte`, `binary`, `date`, `date-time`, `password`, `email`, `hostname`,
  `ipv4`, `ipv6`, `uri`, `uuid` - `string`.

For these formats, it reports `Schema type and format do not match` when the
object has another `type` or no `type` at all. Other formats are left to
[schema-format-unknown](/docs/linter/swagger/rules/schema-format-unknown).

## Configuration

The configuration block is an object with a single optional boolean property,
`fixTypeFromFormat`, which controls whether reported issues can be fixed
automatically (see "Automatic fixes"). The default value is `true`.

**Configuration Example**. The following configuration reports mismatches,
but does not fix them.

```yaml
version: "1.0"
commands:
  lint:
    swagger:
      rules:
        schema-format-type-mismatch:
          - error
          - fixTypeFromFormat: false
```

## Examples

**Good**.

```yaml
swagger: '2.0'
info:
  title: Pets
  version: 1.0.0
paths: {}
definitions:
  Pet:
    type: object
    properties:
      id:
        type: string
        format: uuid
      born_at:
        type: string
        format: date-time
      weight:
        type: number
        format: float
```

**Bad**.

```yaml
swagger: '2.0'
info:
  title: Pets
  version: 1.0.0
paths: {}
definitions:
  Pet:
    type: object
    properties:
      id:
        type: integer
        format: uuid
      born_at:
        format: date-time
```

## Automatic fixes

When `fixTypeFromFormat` is `true` and the linter is invoked with the `--fix`
option, this rule sets the `type` of every reported object to the type the
format applies to. In the "Bad" example above, both properties get
`type: string`.

## When Not to Use It

You may disable this rule if your API uses well-known format names with a
different meaning.

## 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.