Saving the Inverse Side of a ManyToMany

I am having such a hard time trying to fix this issue.
Basically I have a "User" and "Profession" entity and I have a ManyToMany relationship between the two.
The user has the ability to edit their own profile, which they can do it via the form. The form at the moment display all basic information contained in the User table.
I now want to allow users to edit their own professions too, therefore I added the following to my ProfileFormType class:

            ->add('profession', EntityType::class, [
                'class'=> Profession::class,
                'multiple'=> true
            ])

When I try now to edit the profile, I can see the "profession" field with all the options and the one already assigned to the user are selected. The problem starts when I try to add/remove additional professions. When I try to save them, it doesn't do anything and I don't know why.
Inside the "User" class I have this:

    /**
     * @ORM\ManyToMany(targetEntity="App\Entity\Profession", mappedBy="user")
     */
    private $professions;
    ...
    ...

    public function addShowreel(Showreel $showreel): self
    {
        if (!$this->showreels->contains($showreel)) {
            $this->showreels[] = $showreel;
            $showreel->setUser($this);
        }

        return $this;
    }

    public function removeShowreel(Showreel $showreel): self
    {
        if ($this->showreels->contains($showreel)) {
            $this->showreels->removeElement($showreel);
            // set the owning side to null (unless already changed)
            if ($showreel->getUser() === $this) {
                $showreel->setUser(null);
            }
        }

        return $this;
    }

    public function getProfessions(): Collection
    {
        return $this->professions;
    }

    /**
     * @return Collection|Profession[]
     */
    public function getProfession(): Collection
    {
        return $this->professions;
    }

and inside the Profession class, I have this:

    /**
     * @ORM\ManyToMany(targetEntity="App\Entity\User", inversedBy="professions")
     */
    private $user;
    ...
    ...
    /**
     * @return Collection|User[]
     */
    public function getUser(): Collection
    {
        return $this->user;
    }

    public function addUser(User $user): self
    {
        if (!$this->user->contains($user)) {
            $this->user[] = $user;
        }

        return $this;
    }

    public function removeUser(User $user): self
    {
        if ($this->user->contains($user)) {
            $this->user->removeElement($user);
        }

        return $this;
    }

My Profile controller (in the edit function) I have this:

$user = $this->getUser();
$form = $this->createForm(ProfileFormType::class, $user);
$form->handleRequest($request);
if ($form->isSubmitted() && $form->isValid()) {
            $em->persist($user);
            $em->flush();
            return $this->redirectToRoute('grm_profile');
}

Sorry for the length of this post, but I really need some help. I have tried slack, IRC but I can't find anyone who can help me understand what is wrong with it.

Thanks,
Alessandro

Hey Alessandro!

Hmm, ok. Here are the things that I'm looking at to make sure this works correctly:

1) You added a profession field to your form - but the property on your entity is called professions (with an "s"). This should have caused an error. If there is no error, it must mean that you have (I'm guessing?) a getProfession() and setProfession() method in your <coder>User class? Those should not be there. Basically, make sure that in your form, the field is called professions (with an s).

2) Assuming the name of the field in the form is professions, I would next look to make sure that your User class has addProfession() and removeProfession() methods. These should have been generated for you if you created the relationship via make:entity. You should *not* have a setProfessions method. Basically, because the field in your form is called professions, when you submit the form, Symfony will first look for a setProfessions() method. If it exists, it will call it. We actually *don't* want that :). If it does not find this method, it will then look for addProfession() and removeProfession: it will call each method one time for all the professions that were added/removed by the user in the form. We WANT this.

3) Side note: in Profession, it looks like the name of the property is "user". It should be "users" for clarity: it will hold an array of User objects :).

4) Here is the key: ultimately, because the Profession.user (which really should be Profession.user for clarity) is the "owning" side of the relationship, we ultimately need that side of the relation to be set. If the new data were *only* set onto User.professions, Doctrine will not save the updated data in the database. This is almost definitely what's happening to you. To make that happen, if you used make:entity to generate the relationship, the code inside the addProfession() and removeProfession methods will already contain code to do this. That will be enough to updating the Profession.user property and everything will save.

The easiest way to get things cleaned up might be to:

A) remove the relationship entirely from Profession and User (remove all the "user" code from Profession - the property, methods, etc and then remove all the "profession" code from User).

B) Re-generate the relationship with make:entity so that all the properties and methods are set up correctly.

Let me know if this helps!

Cheers!

Where is this in the ''finish' code folder?

Hay Dave,

What exactly can't you find in the "finish/" folder?

Cheers!

I couldn't find any of the code to save the inverse many-to-many. I understand now that the finish folder is the end of this whole course, not this chapter. At the end of this course the many-to-many is turned into a one-to-many / many-to-one so that's why it's not there. Sorry for my misunderstanding, although it would be nice to have the code after each chapter since things keep changing.

Hey Dave,

Sorry for misleading you. Actually, we have an issue about this, but it's not prioritized yet. But for now, you can use our handy expandable code block below each video. You can even expand the entire file by pressing "Show All Lines" button (double arrows in the left top corner of each code block) to get more context. Plus, keep in mind "Copy" button in the right top corner, it prevent you to select the code manually.

Cheers!