# schema-constraints

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

This rule ensures that schema objects define constraints restricting the size
of the underlying data.

## Rule Details

Defining constraints enhances the robustness and reliability of the API's
structure.

The `schema-constraints` rule is designed to ensure that all schema objects
define constraints restricting the size of the underlying data. This includes:

- maximum length, pattern, or format for strings.
- maximum size for arrays.
- maximum number f properties for objects.
- minimum and/or maximum value (either strict or exclusive on each side) for
  integers.

## Configuration

The configuration should be an object whose keys are supported schema types,
and values are boolean values. At least one schema type must be specified.

Supported schema types are `integer`, `number`, `string`, `array` and `object`.

By default, constraints for all supported schema types are verified.

**Configuration Example**. The rule with the following configuration checks
only array and object schemas, and does not check numbers and strings.

```yaml
lint:
  rules:
    schema-constraints:
      - warning
      - array: true
        object: true
```

## Examples

**Good**.

```yaml
components:
  schemas:
    User:
      type: object
      properties:
        username:
          type: string
          maxLength: 20
          pattern: "^[a-z0-9_-]{3,16}$"
        roles:
          type: array
          items:
            type: string
          maxItems: 5
        age:
          type: integer
          minimum: 18
          maximum: 100
      maxProperties: 3
```

**Bad**.

```yaml
components:
  schemas:
    User:
      type: object
      properties:
        username:
          type: string
        roles:
          type: array
          items:
            type: string
        age:
          type: integer
```

## When Not to Use It

If your API does not require specific constraints on its schema objects,
you may not need to use this rule.

## Compatibility

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