Form by_reference + Adder and Remover

Hey ahmedbhs!

1) So when we have a ManyToMany relation always we should add by_reference to our EntityType field ?

Yes... but it depends :p. What I mean is, adding by_reference is probably always a safe option. It would just mean that the form component will call your adder/remover methods instead of modifying (for example) the studiedGenuses object directly. From a PHP perspective, the end result in both cases is really the same: the studiedGenuses will be updated in whatever way is needed. The big difference is that, by calling your adder/remover, the code in those methods can update the other side of the relation (thanks to how make:entity generates those methods).

So, by_reference is probably always a good idea. However, it's only technically needed if you're updating the "inverse" side of a ManyToMany relationship. For example, suppose you have Product that is ManyToMany with Tags. And suppose that the Product.tags is the "owning" side of that relationship. If you have a ProductFormType with a "tags" field that is an EntityType, you would not need to set by_reference to false on that field. The reason is that, on save, Doctrine looks at the Product.tags field to figure out what to do, and that will be updated correctly regardless of the value for by_reference. But if the owning side of the relationship is Tag.products, then you must us by_reference so that the adder/remover methods on Product are called (and these methods then update the Tag object correctly).

Let me know if that makes any sense at all :p

2) Same behavior for ChoiceType and CollectionType?

If you use ChoiceType with Doctrine entities then yes. But usually ChoiceType is handling scalar values, which can't be updated by reference, and so the setter method is always called anyways.

For the CollectionType, this is only a concern if you "allow add" or "allow remove". But it's the same answer as part (1): it's probably always a good idea, but only needed if your form is trying to update the inverse side of the relationship.

3) Normally even without setting by reference to false, the form builder should modify studied genius, because it's already setted to a new arrayCollection via the constructer !

Yes! If you do NOT set 'by_reference'=>false for a "collection" field like this, then it defaults to true. This means that the ArrayCollection object is modified directly without every calling a setter/adder/remove method. In fact, iirc, you could even delete those methods (only have a getter) and things would still work. But, this is not what we want if our form is updating the inverse side of a Doctrine relation: we do want the adder/remove to be called so we can sync the owning side.

Let me know if this helps - it's a complex topic to think about1

Cheers!

Oh man ... Symfony is a great framework but I mention it is too much influenced by our most lovely human beings: womans :-)

The error was caused because Symfony did not found any adder/remover-method even though it exists (and in a singular form)!

To
find the methods our girl symfony is using the PropertyAccessor -
class. It searches for singular forms of the varname and check if this
varname exists. If not BAM! (%**!"!!(/)!/")!). It throws an NoSuchPropertyException (Could not determine access type for property))

I checked with a dump how symfony is thinking the singular form should be. For this I hacked into
vendor\symfony\symfony\src\Symfony\Component\PropertyAccess\PropertyAccessor.php (Method findAdderAndRemover)

Because my varname was not good enough for my lovely symfony I decided to rename it and now it works :)

I met the same situation too.
When I named the variable $studiedGenuses as $studiedGenus
I create the function addStudiedGenus() and removeStudiedGenus()
It threw the exception to me
'Could not determine access type for property "studiedGenus".'

When I changed it back to studiedGenuses . It worked.

Hey 黃俊凱

Symfony has some problems detecting words in plural, I hope in the future it will get better but right now, we have to make him happy and adjust the name of our accessors/variables

Cheers!

Hey Thomas,

I'm glad you got it working so quickly! Really, when you set by_reference to false you have to add adder/remover method, otherwise Symfony can set a value for those properties.

Cheers!

You are right but Symfony simply was not "seeing" my adder/remover-methods dispite they exists. This was caused by the weird Singular-thing.

Ah, now I see. Really, it should be singular form. Just wonder what property name did you use? "varname"?

Cheers!

Internally I used "$bosiContracts" but symfony was not able to determine.

Yeah, you have to add addBosiContract()/removeBosiContract() methods for this property.

Cheers!

... but Symfony did not recognized them.

Hm, then I'm confused... How did you solve it? What exactly adder/remover method names are you using? :)

Cheers!

Hey Ryan, I got the same error in Symfony 3.1.10 when using the studiedGenuses property name:
"Could not determine access type for property "studiedGenuses"
But after adding the "addStudiedGenus" and "removeStudiedGenus" functions it works.

Hey Dominik,

Yeah, with addStudiedGenus/removeStudiedGenus it should work well - you just have to look closer and do not make a misprint. :)

Thanks for sharing it!

Cheers!

Hey ugo .p!

Sorry about that - didn't mean to confuse anyone with the chapter breaks! :)

Hey Jian,

It depends: if you do not use "'by_reference' => false", then setters/getters will be enough for you, otherwise, you'll get fatal error due to the thrown exception if adder/remover won't be found.

Cheers!

And by_reference is important! Because we do want those adder and removers to be called: it's our opportunity to make sure the owning and inverse sides of the relationships are all set correctly :).

Cheers!

Thank you Ryan! u guys reply the comment so frequently which is awesome