Fix error on getNewInstance() when parent object property in uninitialised.

[7ochem]

Subject

When creating a new object instance, the admin will check if there is a parent object that needs to be appended. The appendParentObject() method will check the current value of the property that holds the parent object. But if this property is typed and not yet initialised, Symfony's PropertyAccess will throw an AccessException. This fix catches that exception and continues as if the current value is null.

Note:
I'm catching \Symfony\Component\PropertyAccess\Exception\AccessException. The \Symfony\Component\PropertyAccess\Exception\UninitializedPropertyException (child of AccessException) was introduced in Symfony 5.1 and thus not yet available in Symfony 4.4.

I am targeting the 3.x branch, because this is a bug.

Closes #7703.

Changelog

### Fixed
- Catch AccessException in AbstractAdmin::appendParentObject() to prevent an error when the property for the parent object is uninitialised.

[VincentLanglet]

Note: I'm catching \Symfony\Component\PropertyAccess\Exception\AccessException. The \Symfony\Component\PropertyAccess\Exception\UninitializedPropertyException (child of AccessException) was introduced in Symfony 5.1 and thus not yet available in Symfony 4.4.

Can you add a TODO comment to change to UninitializedPropertyException when dropping support for Symfony < 5.1 ?

[jordisala1991]

what happens if the entity does not have the getParent method? Would this try catch hide some potential problems?

[VincentLanglet]

I would say yes because "noSuchPropertyException" extends AccessException...

Dunno if we can filter the right case we want until support for Sf4.4 is dropped.

Should we check the message of the exception until the use of the new exception ?

[7ochem]

PropertyAccessor throws this exception in 3 cases:

1. The getter is used but a native PHP \Error was catched by PropertyAccessor, the PHP version is >= 7.4 and the message of the error is "Typed property .... must not be accessed before initialization"
2. The property is public and PropertyAccessor detects that is was not set (not initialised)
3. The getter is used but a native PHP \TypeError was catched by PropertyAccessor and the message of the error is "Return value ... must be of type ..., null returned" (in which case the property is untyped and uninitialised and the getter return type is not nullable)

what happens if the entity does not have the getParent method? Would this try catch hide some potential problems?

In case the property exists and is private/protected but the getParent method does not exist (or is private/protected) a \Symfony\Component\PropertyAccess\Exception\NoSuchPropertyException is thrown.

[VincentLanglet]

NoSuchPropertyException

NoSuchPropertyException extends AccessException so it's caught too by your try/catch.
Same for NoSuchIndexException.

Maybe we should add a check if ($e instanceof NoSuchPropertyException || $e instanceof NoSuchIndexException) throw $e.

[7ochem]

I would say yes because "noSuchPropertyException" extends AccessException...

Dunno if we can filter the right case we want until support for Sf4.4 is dropped.

Should we check the message of the exception until the use of the new exception ?

Ok... sharp, I've overlooked that "detail" 😄

I could add:

if (!$e instanceof UninitializedPropertyException && get_class($e) !== AccessException::class) {
    throw $e; // Re-throw. We only want to "ignore" AccessException (Sf < 5.1) and UninitializedPropertyException (Sf >= 5.1)
}

[VincentLanglet]

Yes, I think it would be better with this re-throw

[7ochem]

Ok done. I also updated the todo message for this slightly.

[VincentLanglet]

Linter are failing

[7ochem]

I fixed this one thing in my code, but now PHP CS Fixer is failing on other things. It is using PHP CS Fixer 3.5.0 which has been released 9 hours ago, so maybe this is a bug in that new release

I see PHP-CS-Fixer/PHP-CS-Fixer#6238. That's probably the one causing this.

[VincentLanglet]

@7ochem Can you rebase ? The linter build should be fixed.