Error Identifier: property.readOnlyAssignOutOfClass
Every error reported by PHPStan has an error identifier. Here’s a list of all error identifiers. In PHPStan Pro you can see the error identifier next to each error and filter errors by their identifiers.
Code example #
<?php declare(strict_types = 1);
class Foo
{
public readonly int $bar;
public function __construct(int $bar)
{
$this->bar = $bar;
}
}
class Bar extends Foo
{
public function __construct(int $bar)
{
parent::__construct(1);
$this->bar = $bar;
}
}
Why is it reported? #
PHP’s readonly properties can only be assigned from within the class that declares them. Assigning a readonly property from a child class, an unrelated class, or a standalone function is not allowed, even if the property’s visibility (public or protected) would otherwise permit access.
In the example above, Bar attempts to assign $this->bar inside its constructor, but $bar is declared as readonly in Foo. Since Bar is not the declaring class, this assignment is forbidden.
How to fix it #
Pass the value to the parent constructor so the declaring class performs the initialization:
<?php declare(strict_types = 1);
class Bar extends Foo
{
public function __construct(int $bar)
{
- parent::__construct(1);
- $this->bar = $bar;
+ parent::__construct($bar);
}
}
Or move the readonly property to the class that needs to assign it:
<?php declare(strict_types = 1);
class Bar extends Foo
{
+ public readonly int $baz;
+
public function __construct(int $bar)
{
parent::__construct(1);
- $this->bar = $bar;
+ $this->baz = $bar;
}
}
How to ignore this error #
You can use the identifier property.readOnlyAssignOutOfClass to ignore this error using a comment:
// @phpstan-ignore property.readOnlyAssignOutOfClass
codeThatProducesTheError();You can also use only the identifier key to ignore all errors of the same type in your configuration file in the ignoreErrors parameter:
parameters:
ignoreErrors:
-
identifier: property.readOnlyAssignOutOfClass