Error Identifier: assign.propertyReadOnly

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 function __construct(
		public readonly string $name,
	)
	{
	}
}

$foo = new Foo('bar');
$foo->name = 'baz';

Why is it reported? #

A value is being assigned to a property that is not writable. This typically happens when writing to a readonly property outside its initialization context, or to a property that only defines a get hook without a set hook.

In the example above, the property $name is declared as readonly and has already been initialized in the constructor. Attempting to assign a new value to it outside the constructor is not allowed.

How to fix it #

Avoid assigning to the property after it has been initialized. If you need to change the value, create a new instance instead:

 <?php declare(strict_types = 1);
 
 $foo = new Foo('bar');
-$foo->name = 'baz';
+$foo = new Foo('baz');

How to ignore this error #

You can use the identifier assign.propertyReadOnly to ignore this error using a comment:

// @phpstan-ignore assign.propertyReadOnly
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: assign.propertyReadOnly

Rules that report this error #

PHPStan\Rules\Properties\WritingToReadOnlyPropertiesRule [1]

Edit this page on GitHub

Theme