# schema-format-type-mismatch

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

This rule ensures that the `format` of a schema is consistent with its
`type`.

## Rule Details

Formats apply to values of specific types. A schema such as
`type: integer, format: email` is contradictory: validators ignore the format,
and code generators produce unexpected types.

The `schema-format-type-mismatch` rule checks every schema of an AsyncAPI
document whose `format` is in the
[OpenAPI format registry](https://spec.openapis.org/registry/format/) or in
`openapi.custom_formats` of the configuration file, and reports
`Schema type and format do not match` when none of the schema's types is a JSON
type of the format:

- the integer formats (`int8` to `uint64`, `int32`, `int64`, `double-int`,
  `sf-integer`) need `integer` or `number`, and `int64` and `uint64` also allow
  `string`;
- `float`, `double` and `sf-decimal` need `number`;
- `decimal` and `decimal128` allow `string` and `number`, `unixtime` also
  `integer`;
- the others (`date`, `date-time`, `uuid`, `email`, `http-date`, ...) need
  `string`.

A schema with one of these formats but without a `type` is reported as well.
Other formats are left to
[schema-format-unknown](/docs/linter/asyncapi/rules/schema-format-unknown).
The [Formats](/docs/reference/cli/formats) page lists every format.

## 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:
    asyncapi:
      rules:
        schema-format-type-mismatch:
          - error
          - fixTypeFromFormat: false
```

## Examples

**Good**.

```yaml
asyncapi: 3.0.0
info:
  title: User Events
  version: 1.0.0
components:
  schemas:
    UserSignedUp:
      type: object
      properties:
        email:
          type: string
          format: email
        signed_up_at:
          type: string
          format: date-time
```

**Bad**.

```yaml
asyncapi: 3.0.0
info:
  title: User Events
  version: 1.0.0
components:
  schemas:
    UserSignedUp:
      type: object
      properties:
        email:
          type: integer
          format: email
        signed_up_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 schema to the type the
format applies to. In the "Bad" example above, both properties get
`type: string`.

## When Not to Use It

We recommend to always enable this rule.

## Compatibility

This rule is compatible with AsyncAPI 3.x documents. AsyncAPI 2.x documents
are rejected by the reader and are not linted.