The OptionsResolver Component ¶
The OptionsResolver component is an improved replacement for the array_replace PHP function. It allows you to create an options system with required options, defaults, validation (type, value), normalization and more.
OptionsResolver コンポーネントは、array_replace PHP 関数の改良版です。必要なオプション、デフォルト、検証 (タイプ、値)、正規化などを含むオプション システムを作成できます。
Installation ¶
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$ composer require symfony/options-resolver
|
Note
If you install this component outside of a Symfony application, you must
require the vendor/autoload.php file in your code to enable the class
autoloading mechanism provided by Composer. Read
this article for more details.
Usage ¶
Imagine you have a Mailer class which has four options: host,
username, password and port:
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class Mailer
{
protected $options;
public function __construct(array $options = [])
{
$this->options = $options;
}
}
|
When accessing the $options, you need to add some boilerplate code to
check which options are set:
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class Mailer
{
// ...
public function sendMail($from, $to)
{
$mail = ...;
$mail->setHost($this->options['host'] ?? 'smtp.example.org');
$mail->setUsername($this->options['username'] ?? 'user');
$mail->setPassword($this->options['password'] ?? 'pa$$word');
$mail->setPort($this->options['port'] ?? 25);
// ...
}
}
|
Also, the default values of the options are buried in the business logic of your code. Use the array_replace to fix that:
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class Mailer
{
// ...
public function __construct(array $options = [])
{
$this->options = array_replace([
'host' => 'smtp.example.org',
'username' => 'user',
'password' => 'pa$$word',
'port' => 25,
], $options);
}
}
|
Now all four options are guaranteed to be set, but you could still make an error
like the following when using the Mailer class:
1 2 3 |
$mailer = new Mailer([
'usernme' => 'johndoe', // 'username' is wrongly spelled as 'usernme'
]);
|
No error will be shown. In the best case, the bug will appear during testing, but the developer will spend time looking for the problem. In the worst case, the bug might not appear until it's deployed to the live system.
Fortunately, the OptionsResolver class helps you to fix this problem:
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use Symfony\Component\OptionsResolver\OptionsResolver;
class Mailer
{
// ...
public function __construct(array $options = [])
{
$resolver = new OptionsResolver();
$resolver->setDefaults([
'host' => 'smtp.example.org',
'username' => 'user',
'password' => 'pa$$word',
'port' => 25,
]);
$this->options = $resolver->resolve($options);
}
}
|
Like before, all options will be guaranteed to be set. Additionally, an UndefinedOptionsException is thrown if an unknown option is passed:
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$mailer = new Mailer([
'usernme' => 'johndoe',
]);
// UndefinedOptionsException: The option "usernme" does not exist.
// Defined options are: "host", "password", "port", "username"
|
The rest of your code can access the values of the options without boilerplate code:
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// ...
class Mailer
{
// ...
public function sendMail($from, $to)
{
$mail = ...;
$mail->setHost($this->options['host']);
$mail->setUsername($this->options['username']);
$mail->setPassword($this->options['password']);
$mail->setPort($this->options['port']);
// ...
}
}
|
It's a good practice to split the option configuration into a separate method:
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// ...
class Mailer
{
// ...
public function __construct(array $options = [])
{
$resolver = new OptionsResolver();
$this->configureOptions($resolver);
$this->options = $resolver->resolve($options);
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults([
'host' => 'smtp.example.org',
'username' => 'user',
'password' => 'pa$$word',
'port' => 25,
'encryption' => null,
]);
}
}
|
First, your code becomes easier to read, especially if the constructor does more
than processing options. Second, sub-classes may now override the
configureOptions() method to adjust the configuration of the options:
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// ...
class GoogleMailer extends Mailer
{
public function configureOptions(OptionsResolver $resolver)
{
parent::configureOptions($resolver);
$resolver->setDefaults([
'host' => 'smtp.google.com',
'encryption' => 'ssl',
]);
}
}
|
Required Options ¶
If an option must be set by the caller, pass that option to
setRequired().
For example, to make the host option required, you can do:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setRequired('host');
}
}
|
If you omit a required option, a MissingOptionsException will be thrown:
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$mailer = new Mailer();
// MissingOptionsException: The required option "host" is missing.
|
The setRequired() method accepts a single name or an array of option names if you have more than one required option:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setRequired(['host', 'username', 'password']);
}
}
|
Use isRequired() to find out if an option is required. You can use getRequiredOptions() to retrieve the names of all required options:
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// ...
class GoogleMailer extends Mailer
{
public function configureOptions(OptionsResolver $resolver)
{
parent::configureOptions($resolver);
if ($resolver->isRequired('host')) {
// ...
}
$requiredOptions = $resolver->getRequiredOptions();
}
}
|
If you want to check whether a required option is still missing from the default options, you can use isMissing(). The difference between this and isRequired() is that this method will return false if a required option has already been set:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setRequired('host');
}
}
// ...
class GoogleMailer extends Mailer
{
public function configureOptions(OptionsResolver $resolver)
{
parent::configureOptions($resolver);
$resolver->isRequired('host');
// => true
$resolver->isMissing('host');
// => true
$resolver->setDefault('host', 'smtp.google.com');
$resolver->isRequired('host');
// => true
$resolver->isMissing('host');
// => false
}
}
|
The getMissingOptions() method lets you access the names of all missing options.
Type Validation ¶
You can run additional checks on the options to make sure they were passed correctly. To validate the types of the options, call setAllowedTypes():
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
// specify one allowed type
$resolver->setAllowedTypes('host', 'string');
// specify multiple allowed types
$resolver->setAllowedTypes('port', ['null', 'int']);
// check all items in an array recursively for a type
$resolver->setAllowedTypes('dates', 'DateTime[]');
$resolver->setAllowedTypes('ports', 'int[]');
}
}
|
You can pass any type for which an is_<type>() function is defined in PHP.
You may also pass fully qualified class or interface names (which is checked
using instanceof). Additionally, you can validate all items in an array
recursively by suffixing the type with [].
If you pass an invalid option now, an InvalidOptionsException is thrown:
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$mailer = new Mailer([
'host' => 25,
]);
// InvalidOptionsException: The option "host" with value "25" is
// expected to be of type "string", but is of type "int"
|
In sub-classes, you can use addAllowedTypes() to add additional allowed types without erasing the ones already set.
Value Validation ¶
Some options can only take one of a fixed list of predefined values. For
example, suppose the Mailer class has a transport option which can be
one of sendmail, mail and smtp. Use the method
setAllowedValues()
to verify that the passed option contains one of these values:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setDefault('transport', 'sendmail');
$resolver->setAllowedValues('transport', ['sendmail', 'mail', 'smtp']);
}
}
|
If you pass an invalid transport, an InvalidOptionsException is thrown:
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$mailer = new Mailer([
'transport' => 'send-mail',
]);
// InvalidOptionsException: The option "transport" with value "send-mail"
// is invalid. Accepted values are: "sendmail", "mail", "smtp"
|
For options with more complicated validation schemes, pass a closure which
returns true for acceptable values and false for invalid values:
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// ...
$resolver->setAllowedValues('transport', function ($value) {
// return true or false
});
|
Tip
You can even use the Validator component to validate the input by using the createIsValidCallable() method:
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use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Validator\Constraints\Length;
use Symfony\Component\Validator\Validation;
// ...
$resolver->setAllowedValues('transport', Validation::createIsValidCallable(
new Length(['min' => 10 ])
));
|
In sub-classes, you can use addAllowedValues() to add additional allowed values without erasing the ones already set.
Option Normalization ¶
Sometimes, option values need to be normalized before you can use them. For
instance, assume that the host should always start with http://. To do
that, you can write normalizers. Normalizers are executed after validating an
option. You can configure a normalizer by calling
setNormalizer():
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use Symfony\Component\OptionsResolver\Options;
// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setNormalizer('host', function (Options $options, $value) {
if ('http://' !== substr($value, 0, 7)) {
$value = 'http://'.$value;
}
return $value;
});
}
}
|
The normalizer receives the actual $value and returns the normalized form.
You see that the closure also takes an $options parameter. This is useful
if you need to use other options during normalization:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setNormalizer('host', function (Options $options, $value) {
if ('http://' !== substr($value, 0, 7) && 'https://' !== substr($value, 0, 8)) {
if ('ssl' === $options['encryption']) {
$value = 'https://'.$value;
} else {
$value = 'http://'.$value;
}
}
return $value;
});
}
}
|
To normalize a new allowed value in subclasses that are being normalized
in parent classes, use addNormalizer() method.
This way, the $value argument will receive the previously normalized
value, otherwise you can prepend the new normalizer by passing true as
third argument.
Default Values that Depend on another Option ¶
Suppose you want to set the default value of the port option based on the
encryption chosen by the user of the Mailer class. More precisely, you want
to set the port to 465 if SSL is used and to 25 otherwise.
You can implement this feature by passing a closure as the default value of
the port option. The closure receives the options as arguments. Based on
these options, you can return the desired default value:
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use Symfony\Component\OptionsResolver\Options;
// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setDefault('encryption', null);
$resolver->setDefault('port', function (Options $options) {
if ('ssl' === $options['encryption']) {
return 465;
}
return 25;
});
}
}
|
Caution
The argument of the callable must be type hinted as Options. Otherwise,
the callable itself is considered as the default value of the option.
Note
The closure is only executed if the port option isn't set by the user
or overwritten in a subclass.
A previously set default value can be accessed by adding a second argument to the closure:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setDefaults([
'encryption' => null,
'host' => 'example.org',
]);
}
}
class GoogleMailer extends Mailer
{
public function configureOptions(OptionsResolver $resolver)
{
parent::configureOptions($resolver);
$resolver->setDefault('host', function (Options $options, $previousValue) {
if ('ssl' === $options['encryption']) {
return 'secure.example.org';
}
// Take default value configured in the base class
return $previousValue;
});
}
}
|
As seen in the example, this feature is mostly useful if you want to reuse the default values set in parent classes in sub-classes.
Options without Default Values ¶
In some cases, it is useful to define an option without setting a default value. This is useful if you need to know whether or not the user actually set an option or not. For example, if you set the default value for an option, it's not possible to know whether the user passed this value or if it comes from the default:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setDefault('port', 25);
}
// ...
public function sendMail($from, $to)
{
// Is this the default value or did the caller of the class really
// set the port to 25?
if (25 === $this->options['port']) {
// ...
}
}
}
|
You can use setDefined() to define an option without setting a default value. Then the option will only be included in the resolved options if it was actually passed to resolve():
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setDefined('port');
}
// ...
public function sendMail($from, $to)
{
if (array_key_exists('port', $this->options)) {
echo 'Set!';
} else {
echo 'Not Set!';
}
}
}
$mailer = new Mailer();
$mailer->sendMail($from, $to);
// => Not Set!
$mailer = new Mailer([
'port' => 25,
]);
$mailer->sendMail($from, $to);
// => Set!
|
You can also pass an array of option names if you want to define multiple options in one go:
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// ...
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->setDefined(['port', 'encryption']);
}
}
|
The methods isDefined() and getDefinedOptions() let you find out which options are defined:
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// ...
class GoogleMailer extends Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
parent::configureOptions($resolver);
if ($resolver->isDefined('host')) {
// One of the following was called:
// $resolver->setDefault('host', ...);
// $resolver->setRequired('host');
// $resolver->setDefined('host');
}
$definedOptions = $resolver->getDefinedOptions();
}
}
|
Nested Options ¶
Suppose you have an option named spool which has two sub-options type
and path. Instead of defining it as a simple array of values, you can pass a
closure as the default value of the spool option with a
OptionsResolver argument. Based on
this instance, you can define the options under spool and its desired
default value:
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class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefault('spool', function (OptionsResolver $spoolResolver) {
$spoolResolver->setDefaults([
'type' => 'file',
'path' => '/path/to/spool',
]);
$spoolResolver->setAllowedValues('type', ['file', 'memory']);
$spoolResolver->setAllowedTypes('path', 'string');
});
}
public function sendMail($from, $to)
{
if ('memory' === $this->options['spool']['type']) {
// ...
}
}
}
$mailer = new Mailer([
'spool' => [
'type' => 'memory',
],
]);
|
Nested options also support required options, validation (type, value) and
normalization of their values. If the default value of a nested option depends
on another option defined in the parent level, add a second Options argument
to the closure to access to them:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefault('sandbox', false);
$resolver->setDefault('spool', function (OptionsResolver $spoolResolver, Options $parent) {
$spoolResolver->setDefaults([
'type' => $parent['sandbox'] ? 'memory' : 'file',
// ...
]);
});
}
}
|
Caution
The arguments of the closure must be type hinted as OptionsResolver and
Options respectively. Otherwise, the closure itself is considered as the
default value of the option.
In same way, parent options can access to the nested options as normal arrays:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 |
class Mailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefault('spool', function (OptionsResolver $spoolResolver) {
$spoolResolver->setDefaults([
'type' => 'file',
// ...
]);
});
$resolver->setDefault('profiling', function (Options $options) {
return 'file' === $options['spool']['type'];
});
}
}
|
Note
The fact that an option is defined as nested means that you must pass an array of values to resolve it at runtime.
Prototype Options ¶
There are situations where you will have to resolve and validate a set of
options that may repeat many times within another option. Let's imagine a
connections option that will accept an array of database connections
with host, database, user and password each.
The best way to implement this is to define the connections option as prototype:
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$resolver->setDefault('connections', function (OptionsResolver $connResolver) {
$connResolver
->setPrototype(true)
->setRequired(['host', 'database'])
->setDefaults(['user' => 'root', 'password' => null]);
});
|
According to the prototype definition in the example above, it is possible to have multiple connection arrays like the following:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
$resolver->resolve([
'connections' => [
'default' => [
'host' => '127.0.0.1',
'database' => 'symfony',
],
'test' => [
'host' => '127.0.0.1',
'database' => 'symfony_test',
'user' => 'test',
'password' => 'test',
],
// ...
],
]);
|
The array keys (default, test, etc.) of this prototype option are
validation-free and can be any arbitrary value that helps differentiate the
connections.
Note
A prototype option can only be defined inside a nested option and during its resolution it will expect an array of arrays.
Deprecating the Option ¶
Once an option is outdated or you decided not to maintain it anymore, you can deprecate it using the setDeprecated() method:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
$resolver
->setDefined(['hostname', 'host'])
// this outputs the following generic deprecation message:
// Since acme/package 1.2: The option "hostname" is deprecated.
->setDeprecated('hostname', 'acme/package', '1.2')
// you can also pass a custom deprecation message (%name% placeholder is available)
->setDeprecated(
'hostname',
'acme/package',
'1.2',
'The option "hostname" is deprecated, use "host" instead.'
)
;
|
Note
The deprecation message will be triggered only if the option is being used somewhere, either its value is provided by the user or the option is evaluated within closures of lazy options and normalizers.
Note
When using an option deprecated by you in your own library, you can pass
false as the second argument of the
offsetGet() method
to not trigger the deprecation warning.
Instead of passing the message, you may also pass a closure which returns a string (the deprecation message) or an empty string to ignore the deprecation. This closure is useful to only deprecate some of the allowed types or values of the option:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 |
$resolver
->setDefault('encryption', null)
->setDefault('port', null)
->setAllowedTypes('port', ['null', 'int'])
->setDeprecated('port', 'acme/package', '1.2', function (Options $options, $value) {
if (null === $value) {
return 'Passing "null" to option "port" is deprecated, pass an integer instead.';
}
// deprecation may also depend on another option
if ('ssl' === $options['encryption'] && 456 !== $value) {
return 'Passing a different port than "456" when the "encryption" option is set to "ssl" is deprecated.';
}
return '';
})
;
|
Note
Deprecation based on the value is triggered only when the option is provided by the user.
This closure receives as argument the value of the option after validating it and before normalizing it when the option is being resolved.
Chaining Option Configurations ¶
In many cases you may need to define multiple configurations for each option.
For example, suppose the InvoiceMailer class has an host option that is required
and a transport option which can be one of sendmail, mail and smtp.
You can improve the readability of the code avoiding to duplicate option name for
each configuration using the define()
method:
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// ...
class InvoiceMailer
{
// ...
public function configureOptions(OptionsResolver $resolver)
{
// ...
$resolver->define('host')
->required()
->default('smtp.example.org')
->allowedTypes('string')
->info('The IP address or hostname');
$resolver->define('transport')
->required()
->default('transport')
->allowedValues('sendmail', 'mail', 'smtp');
}
}
|
Performance Tweaks ¶
With the current implementation, the configureOptions() method will be
called for every single instance of the Mailer class. Depending on the
amount of option configuration and the number of created instances, this may add
noticeable overhead to your application. If that overhead becomes a problem, you
can change your code to do the configuration only once per class:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 |
// ...
class Mailer
{
private static $resolversByClass = [];
protected $options;
public function __construct(array $options = [])
{
// What type of Mailer is this, a Mailer, a GoogleMailer, ... ?
$class = get_class($this);
// Was configureOptions() executed before for this class?
if (!isset(self::$resolversByClass[$class])) {
self::$resolversByClass[$class] = new OptionsResolver();
$this->configureOptions(self::$resolversByClass[$class]);
}
$this->options = self::$resolversByClass[$class]->resolve($options);
}
public function configureOptions(OptionsResolver $resolver)
{
// ...
}
}
|
Now the OptionsResolver instance
will be created once per class and reused from that on. Be aware that this may
lead to memory leaks in long-running applications, if the default options contain
references to objects or object graphs. If that's the case for you, implement a
method clearOptionsConfig() and call it periodically:
1 2 3 4 5 6 7 8 9 10 11 12 |
// ...
class Mailer
{
private static $resolversByClass = [];
public static function clearOptionsConfig()
{
self::$resolversByClass = [];
}
// ...
}
|
That's it! You now have all the tools and knowledge needed to process options in your code.