---
title: "Rule – API-Referenz · Quittio"
description: "A business or plausibility rule checked in PHP (levels L1 to L3 and L7)."
canonical_url: "https://quittio.dev/docs/api/Quittio/Core/Validation/Rule"
locale: de
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  "og:description": "A business or plausibility rule checked in PHP (levels L1 to L3 and L7)."
  "og:image": "https://quittio.dev/og/quittio-de.jpg"
  "og:image:alt": "Quittio: E-Rechnungen für PHP und Laravel. Rechtssicher, validiert, archiviert, mit geprüfter Beispielrechnung."
  "og:image:height": "630"
  "og:image:type": image/jpeg
  "og:image:width": "1200"
  "og:title": "Rule – API-Referenz · Quittio"
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  "twitter:image:alt": "Quittio: E-Rechnungen für PHP und Laravel. Rechtssicher, validiert, archiviert, mit geprüfter Beispielrechnung."
---

> Index of every page on this site: [llms.txt](https://quittio.dev/llms.txt)

[API reference](https://quittio.dev/docs/api) / [Quittio](https://quittio.dev/docs/api/Quittio) \\ [Core](https://quittio.dev/docs/api/Quittio/Core) \\ [Validation](https://quittio.dev/docs/api/Quittio/Core/Validation)

# Rule

interface in quittio/core

`Quittio\Core\Validation\Rule` · [Source](https://github.com/Quittio/quittio/blob/v0.7.1/packages/core/src/Validation/Rule.php#L12)

A business or plausibility rule checked in PHP (levels L1 to L3 and L7).

## Methods \#

| Method | Description |
| --- | --- |
| `->check()` | |
| `->code()` | Official rule code (e.g. BR-CO-25, BR-DE-1) or a package code (QUITTIO-…). |
| `->level()` | |

### `check()`#

```
public function check(
    InvoiceData $invoice,
    ValidationContext $context,
): iterable<ValidationMessage>
```

| Parameter | Type | Description |
| --- | --- | --- |
| `$invoice` | `[InvoiceData](https://quittio.dev/docs/api/Quittio/Core/Data/InvoiceData)` | |
| `$context` | `[ValidationContext](https://quittio.dev/docs/api/Quittio/Core/Validation/ValidationContext)` | |

<dl><dt>Returns</dt>
<dd><code>iterable&lt;<a href="https://quittio.dev/docs/api/Quittio/Core/Validation/ValidationMessage">ValidationMessage</a>&gt;</code></dd>
</dl>

### `code()`#

```
public function code(): string
```

Official rule code (e.g. BR-CO-25, BR-DE-1) or a package code (QUITTIO-…).

<dl><dt>Returns</dt>
<dd><code>string</code></dd>
</dl>

### `level()`#

```
public function level(): ValidationLevel
```

<dl><dt>Returns</dt>
<dd><code><a href="https://quittio.dev/docs/api/Quittio/Core/Validation/ValidationLevel">ValidationLevel</a></code></dd>
</dl>

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