# schema-format-defined

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

This rule ensures that every schema object that is a string or a number has
its format defined.

## Rule Details

Defining the format of a string or numeric schema objects enhances the
readability and understanding of the API's structure.

The `schema-format-defined` rule is designed to ensure that all schema objects
whose type is `number` or `integer` have also a `format` property defined: an
integer format of the [OpenAPI format registry](/docs/reference/cli/formats)
(`int8` to `uint64`, `int32`, `int64`, `double-int`, `sf-integer`) or
`unixtime` for `integer`, a number format (`float`, `double`, `decimal`, ...)
for `number`, or a format of `openapi.custom_formats` of the matching type.

## Configuration

None.

## Examples

**Good**. Now it is obvious that `birthDate` is a ISO8601 date string.

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

**Bad**. It is not immediately obvious how `birthDate` is formated. Is it
`YYYY-MM-DD` or `DD-MM-YY`, or perhaps `YY/MM/DD` ?

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

## When Not to Use It

We recommend to always enable this rule.

## Compatibility

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