Nette Schema
A library for validating and normalizing data structures against a defined schema. Declare what correct data looks like, and Schema verifies and transforms input in one step.
shell
composer require nette/schema
When to Use Schema
- Configuration validation – validate config arrays loaded from .neon files
- API input validation – validate request data before processing
- Data import/transform – normalize external data into typed structures
- DI extension config – validate extension configuration in
loadConfiguration()
Schema is complementary to Nette Forms (which handles user input with UI) and database constraints (which enforce storage-level rules). Use Schema for programmatic data validation where there's no form UI.
Basic Usage
php
use Nette\Schema\Expect;
use Nette\Schema\Processor;
$schema = Expect::structure([
'name' => Expect::string()->required(),
'email' => Expect::email(),
'age' => Expect::int()->min(0)->max(120),
]);
$processor = new Processor;
try {
$normalized = $processor->process($schema, $data);
// $normalized is stdClass with validated data
} catch (Nette\Schema\ValidationException $e) {
echo 'Invalid: ' . $e->getMessage();
// $e->getMessages() returns array of all errors
}
Data Types
php
Expect::string() // string, default null
Expect::string('default') // string with default value
Expect::int() // integer
Expect::float() // float
Expect::bool() // boolean
Expect::null() // null only
Expect::array() // array, default []
Expect::scalar() // scalar value
Expect::type('ClassName') // instance of class
Expect::type('bool|string') // union types
Arrays
php
// Array of strings
Expect::arrayOf('string')
Expect::arrayOf(Expect::string())
// Array with string keys
Expect::arrayOf('string', 'string')
// List (indexed array)
Expect::listOf('string')
// Tuple (fixed positions)
Expect::array([
Expect::int(),
Expect::string(),
Expect::bool(),
])
Structures
php
$schema = Expect::structure([
'database' => Expect::structure([
'host' => Expect::string()->required(),
'port' => Expect::int(3306),
'user' => Expect::string()->required(),
'password' => Expect::string()->nullable(),
]),
'debug' => Expect::bool(false),
]);
Properties are optional by default (null). Use required() for mandatory fields.
Enumeration
php
// One of specific values
Expect::anyOf('small', 'medium', 'large')
// One of values or schemas
Expect::anyOf(
Expect::string(),
Expect::int(),
null
)
// First is default
Expect::anyOf('small', 'medium', 'large')->firstIsDefault()
Constraints
php
// Required field
Expect::string()->required()
// Nullable (accepts null)
Expect::string()->nullable()
// Default value
Expect::string()->default('hello')
Expect::string('hello') // shorthand
// Length/count limits
Expect::string()->min(3)->max(100)
Expect::array()->min(1)->max(10)
// Numeric range
Expect::int()->min(0)->max(100)
// Pattern
Expect::string()->pattern('\d{5}') // regex for entire value
Assertions
php
// Custom validation
Expect::string()->assert(fn($s) => strlen($s) % 2 === 0, 'Must be even length')
// Built-in validators
Expect::string()->assert('is_file')
Expect::string()->assert('ctype_alpha')
Transformations
php
// Transform value after validation
Expect::string()->transform(fn($s) => strtoupper($s))
// Chain transformations
Expect::string()
->assert('ctype_lower', 'Must be lowercase')
->transform(fn($s) => strtoupper($s))
// Transform with validation
Expect::string()->transform(function ($s, $context) {
if (!ctype_alpha($s)) {
// $code is REQUIRED – a single-argument call is an ArgumentCountError
$context->addError('Must be letters only', Nette\Schema\Message::FailedAssertion);
return null;
}
return strtoupper($s);
})
Casting
php
// Cast to type
Expect::scalar()->castTo('string')
Expect::scalar()->castTo('int')
Expect::scalar()->castTo('bool')
// Cast to class (without constructor)
Expect::structure([
'name' => Expect::string(),
'age' => Expect::int(),
])->castTo(Person::class)
// Cast to class with constructor
Expect::structure([
'host' => Expect::string(),
'port' => Expect::int(),
])->castTo(DatabaseConfig::class)
// Creates: new DatabaseConfig(host: ..., port: ...)
Normalization (before)
php
// Normalize before validation
Expect::arrayOf('string')
->before(fn($v) => is_string($v) ? explode(' ', $v) : $v)
// Now accepts both:
// - ['a', 'b', 'c']
// - 'a b c' (converted to array)
Structure Options
php
// Allow extra items
Expect::structure([
'known' => Expect::string(),
])->otherItems(Expect::mixed())
// Skip default values in output
Expect::structure([
'debug' => Expect::bool(false),
])->skipDefaults()
// Extend structure
$base = Expect::structure(['name' => Expect::string()]);
$extended = $base->extend(['email' => Expect::email()]);
From Class
Generate schema from class properties:
php
class Config
{
public string $name;
public ?string $email = null;
public bool $debug = false;
}
$schema = Expect::from(new Config);
// Override specific fields
$schema = Expect::from(new Config, [
'email' => Expect::email()->required(),
]);
Deprecation
php
$schema = Expect::structure([
'oldOption' => Expect::int()->deprecated('Use newOption instead'),
'newOption' => Expect::int(),
]);
$processor->process($schema, $data);
$warnings = $processor->getWarnings();
Practical Examples
Configuration validation:
php
$configSchema = Expect::structure([
'database' => Expect::structure([
'driver' => Expect::anyOf('mysql', 'pgsql', 'sqlite')->required(),
'host' => Expect::string('localhost'),
'port' => Expect::int(),
'name' => Expect::string()->required(),
'user' => Expect::string()->required(),
'password' => Expect::string()->nullable(),
])->castTo('array'),
'cache' => Expect::structure([
'enabled' => Expect::bool(true),
'ttl' => Expect::int(3600)->min(0),
]),
'mail' => Expect::structure([
'from' => Expect::email()->required(),
'smtp' => Expect::structure([
'host' => Expect::string(),
'port' => Expect::int(587),
'secure' => Expect::anyOf('tls', 'ssl', null),
]),
]),
]);
API input validation:
php
$createUserSchema = Expect::structure([
'username' => Expect::string()
->required()
->min(3)->max(20)
->pattern('[a-z0-9_]+'),
'email' => Expect::email()->required(),
'password' => Expect::string()->required()->min(8),
'roles' => Expect::listOf(
Expect::anyOf('user', 'admin', 'moderator')
)->default(['user'])->mergeDefaults(false),
])->castTo('array');
Defaults of arrays and lists are MERGED into the input, not replaced. Without mergeDefaults(false) above, a client sending ['admin'] ends up with ['user', 'admin'] – the default silently survives. That is harmless for config (where merging is the point) and a privilege bug for API input.
Documentation
The full Nette documentation for this topic is bundled with the plugin. Read a page when you need details beyond this skill:
- Schema – every Expect method and the Processor