Error Identifier: assign.propertyReadOnly

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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);

/**
 * @property-read int $readOnlyProperty
 */
class Foo
{
	public function __get(string $name): int
	{
		return 0;
	}

	public function doFoo(): void
	{
		$this->readOnlyProperty = 1;
	}
}

Why is it reported? #

A value is being assigned to a property that is declared as read-only via a @property-read PHPDoc tag. Such a property is intended only for reading — there is no corresponding @property-write or @property tag that would allow writes.

In the example above, $readOnlyProperty is declared with @property-read, so assigning to it inside the class is not allowed.

How to fix it #

Remove the assignment, or if writes are needed, change the PHPDoc tag to @property to allow both reading and writing:

-/**
- * @property-read int $readOnlyProperty
- */
+/**
+ * @property int $readOnlyProperty
+ */
 class Foo
 {

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]