This extension represents an incorrect type mismatch for the simple_array type

[stof]

The simple_array type converts NULL database values to an empty array: https://github.com/doctrine/dbal/blob/3.6.1/src/Types/SimpleArrayType.php#L53-L57
This means that a nullable column does not mean that the PHP property needs to be nullable.

This would probably require a way for type descriptors to tell whether they have a special handling of null or no.

[ondrejmirtes]

What's your code and what error phpstan-doctrine reports?

[stof]

the code looks like this:

    /**
     * @var list<string>
     *
     * @ORM\Column(type="simple_array", nullable=true)
     */
    private $subnetFilters = [];

phpstan-doctrine report this:

Property Incenteev\WebBundle\Entity\Organization::$subnetFilters type mapping mismatch: database can contain array|null but property expects list<string>.

The array vs list<string> part is easy to solve (the type description is not precise enough right now, but SimpleArrayType indeed returns a list<string>).
But the nullability part is handled at https://github.com/phpstan/phpstan-doctrine/blob/62bd362b432fe29e175168689510ddd927b698f8/src/Type/Doctrine/Query/QueryResultTypeWalker.php#L1342C8-L1365 (and maybe other places). The TypeDescriptor interface currently describes only the type for non-null database values and the code elsewhere assumes that a NULL value from the DB is converted to null in PHP all the type. But this assumption is wrong (most types work this way but not all).
I guess we should have TypeDescriptor::getDatabaseNullType(): Type returning the type used to represent the NULL value.

[ondrejmirtes]

I get it, your suggestion makes sense, but I see Doctrine's behaviour as very surprising here. You can also get rid of this mess if you make the column non-nullable and represent empty arrays not in two ways (null and []), but only a single way ([]).

[stof]

@ondrejmirtes in the DB, an empty array is always represented as NULL, not as an empty string: https://github.com/doctrine/dbal/blob/3.6.1/src/Types/SimpleArrayType.php#L37-L44

So making the DB field non-nullable actually forbids storing an empty array.

[ondrejmirtes]

This leads to more constraints that should be reported here: Non-nullable column should only be combined with non-empty-array

[stof]

If we want to solve that, we would need 2 new methods actually, one describing the PHP type corresponding to a DB NULL value as suggested in my previous comment, and one representing the PHP types that gets written as a NULL value.

And then, SimpleArrayType::getWritableToDatabaseType would be amended to report non-empty-array<string> instead of string[]

[micheh]

This is a duplicate of #222