# schema-format-type-mismatch

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

This rule checks all schema objects and warns if any of them have their `type`
and `format` properties contradicting each other.

## Rule Details

Contradicting `type` and `format` properties can lead to confusion and
misinterpretation of the API's structure.

The `schema-format-type-mismatch` rule is designed to ensure that all schema
objects have their `type` and `format` properties in agreement. It reports a
schema whose `format` is in the
[OpenAPI format registry](https://spec.openapis.org/registry/format/) when none
of the schema's types is a JSON type of that format (see
[Formats](/docs/reference/cli/formats) for the list). For example:

- `date`, `uuid`, `email`, `http-date`, `language` and the other string
  formats need `type: string`;
- `int8` to `uint64`, `int32`, `int64`, `double-int` and `sf-integer` need
  `type: integer` or `type: number`;
- `float`, `double` and `sf-decimal` need `type: number` (not `integer`);
- `int64` and `uint64` also allow `type: string`, and `decimal` and
  `decimal128` allow `string` and `number`, as the registry does;
- `unixtime` allows `integer`, `number` and `string`.

The formats of `openapi.custom_formats` in the
[configuration file](/docs/reference/cli/configuration) are checked against
the type given there, and override the registry's.

A schema without a `type` is reported too. Formats neither in the registry nor
custom are left to [schema-format-unknown](/docs/linter/openapi/rules/schema-format-unknown).

## Configuration

The optional `fixTypeFromFormat` boolean controls whether `--fix` replaces a
mismatched schema type with the recognized format's type. It defaults to `true`.

## Examples

**Good**.

```yaml
components:
  schemas:
    User:
      type: object
      properties:
        birthDate:
          type: string
          format: date
```

**Bad**.

```yaml
components:
  schemas:
    User:
      type: object
      properties:
        birthDate:
          type: integer
          format: date
```

## When Not to Use It

We recommend to always enable this rule.

## Automatic fixes

When invoked with `--fix`, the schema gets the singleton type of its format:
integer formats set `integer`, `decimal` and `decimal128` set `string`, the
other number formats set `number` and string formats set `string`. Unknown
formats remain manual.

## Compatibility

This rule is compatible with all OpenAPI 3.x versions.