---
title: "Introduction"
description: "Validate, convert, interpret and inspect PHP values with explicit contracts"
type: "docs"
category: "doc"
tags: []
authors: [Anonymous]
date: "2026-10-26"
last_update: "2026-10-26"
time_minutes: 2
draft: false
unlisted: false
url: "https://www.derafu.dev/docs/data/value/introduction"
---

# Value Validation and Conversion

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`derafu/value` provides composable types, strict scalar reads, explicit conversions, automatic interpretation and value inspection. It requires PHP 8.5 or later and `derafu/translation`.

## Installation

```bash
composer require derafu/value
```

## Components

All four public utility classes live in `Derafu\Value`.

| Class | Responsibility | Guide |
| --- | --- | --- |
| `ValueCaster` | Read scalar values strictly or request explicit conversions. | [Casting](casting) |
| `ValueParser` | Interpret individual values, with optional numeric format and precision preservation. | [Parsing](parsing) |
| `ValueType` | Compose strict checks, explicit conversions, enums, dates and collection types. | [Types](types) |
| `ValueInspector` | Inspect values without converting or normalizing them. | [Inspection](inspection) |

`ValueType<T>` is a `final readonly` object. The other classes expose static methods. Errors support translation through [Derafu Translation](https://www.derafu.dev/docs/core/translation); see [Exceptions and Translations](translations).

## Choose an Operation

```php
use Derafu\Value\ValueCaster;
use Derafu\Value\ValueInspector;
use Derafu\Value\ValueParser;
use Derafu\Value\ValueType;

ValueCaster::requireInt(12);    // 12; rejects null and non-integers
ValueCaster::getInt(null);      // null; rejects other non-integers
ValueType::int()->parse(12);     // 12; strings would be rejected
ValueCaster::toInt('12.0');      // 12; the destination type is explicit
ValueParser::parse('12.0');      // 12; the parser chooses the interpretation
ValueInspector::isBlank('');    // true; inspection does not convert anything
```

Strict types validate the supplied PHP type. ValueCaster provides getXXX()/requireXXX() for strict scalar reads and toXXX() for explicit conversions. String reads additionally accept Stringable. The parser recognizes supported text representations and keeps unrecognized text intact. None of these operations reads array keys or assigns defaults.

## Null and Collections

`ValueCaster::getXXX()` and `toXXX()` preserve null; `requireXXX()` rejects it. A conversion type such as `ValueType::toInt()` rejects it unless `nullable()` is explicitly applied. The parser returns native non-text values unchanged, including `null`, arrays, objects without `Stringable` and resources.

Collection types validate or convert their elements because that traversal is explicitly part of their type definition. `ValueParser` processes one value and does not recurse into arrays.



---
Last updated on 26/10/2026