Error Identifier: property.onlyRead

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
{
	private int $counter;

	public function getCounter(): int
	{
		return $this->counter;
	}
}

Why is it reported? #

The private property is read but never written to anywhere in the class. Since it is private, no code outside the class can assign a value to it either. This means the property will always hold its default value (or be uninitialized), which usually indicates dead code or a missing assignment.

How to fix it #

Write to the property where appropriate, for example in the constructor:

 <?php declare(strict_types = 1);
 
 class Foo
 {
 	private int $counter;

+	public function __construct(int $initial)
+	{
+		$this->counter = $initial;
+	}
+
 	public function getCounter(): int
 	{
 		return $this->counter;
 	}
 }

If the property is no longer needed, remove it and its usages.

How to ignore this error #

You can use the identifier property.onlyRead to ignore this error using a comment:

// @phpstan-ignore property.onlyRead
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.onlyRead

Rules that report this error #

PHPStan\Rules\DeadCode\UnusedPrivatePropertyRule [1]

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