ManyToMany Relationship

There is a header "AJAX and JSON Responses"
Looks it is something that should be changed because there is nothing about AJAX or JSON

Hey!
Why exactly do you need to create this __construct function? Could you elaborate a little bit further on this? Thanks!

Hi Ryan,

I am stuck at a problem that in theory sounds pretty straight forward but in Symfony I am not able to implement it so I am hoping you can push me in right direction. I will explain first what I am trying to do and let you know how far did I get trying to achieve this. Just for your information I am using Symfony 3.0

<strong>What I am trying to do</strong>
1) I have two Entity 'Post' and 'Category' and they are linked together in ManytoMany relationship bidirectional.
2) When I am creating a new post, I want to assign it a category which should be checkboxes and linked with Category Entity
3) After saving the post, when I edit it the category checkboxes should appear as selected (those categories that are assigned to the post)

<strong>What I have done so far</strong>
Entity are already linked and the relationship seems to be working fine because when i save the post it gets saved and the join table of category and entity gets updated as well with post id and category id. If i select multiple categories they get saved as well in the join table.

<strong>What i am stuck at</strong>
When I edit the post, the post data appears fine but the category check boxes do not appear as selected and this is where i need your help.

<strong>How i created the form.</strong>
I am not sure if this is the right way to do it but it seems to be working, so if i am wrong somewhere and not doing it right the symfony way please do correct me.

The <I>CategoryType</I> is straight forward

class CategoryType extends AbstractType
{
    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('name');
    }

    /**
     * @param OptionsResolver $resolver
     */
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'MyBundle\Entity\Category'
        ));
    }
}

Here is the <I>PostType</I>, this is where i have doubt if i have done it right.

class PostType extends AbstractType
{

    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('title')
            ->add('description')
            ->add('featuredImage', FileType::class, array(
                'data_class' => null,
                'constraints' => array(new Image(
                    array(
                        'mimeTypes' => array(
                            "image/jpeg",
                            "image/jpg",
                            "image/png",
                            "image/x-png",
                            "image/pjpeg"
                        ),
                        'mimeTypesMessage' => "Only jpeg and png images are allowed",
                        'maxHeight' => '600',
                        'maxWidth' => '600'
                    )))))
            ->add('category', EntityType::class, array(
                    'class' => 'MyBundle\Entity\Category',
                    'choice_label' => 'name',
                    'multiple'     => true,
                    'expanded'     => true,
                    'by_reference' => false,
                    ))
            ->add('categories', CollectionType::class, array(
                    'entry_type' => CategoryType::class,
                    'by_reference' => false
                ));;
    }

    /**
     * @param OptionsResolver $resolver

     */
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(

            'data_class' => 'MyBundle\Entity\Post'
        ));
    }
}

In order for me to display the already created categories i created a new property in Post entity with name 'Category' which in the <I>PostType</I> is pulling the categories from Category Entity.

Then there is categories CollectionType as well. When the form is submitted i use the loop to add categories in the join table.

            $catagories = $form->get('category')->getData();
            foreach ($catagories as $cat) {
                $post->getCategories()->add($cat);
            }

Doing this does save the information in join table but when I edit it the checkboxes do not appear as selected. Another strange thing I noticed if i remove the ->add('categories', CollectionType::class from the <i>PostType</i> I get the following error which is really wierd because these values DONT exist in the table so i am not sure why it says they are duplicate

An exception occurred while executing 'INSERT INTO posts_categories (post_id, category_id) VALUES (?, ?)' with params [30, 1]:
SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '30-1' for key 'PRIMARY'

This is manyTomany from post.orm.yml

manyToMany:
    categories:
        targetEntity: MyBundle\Entity\Category
        inversedBy: posts
        joinTable:
            name: posts_categories
            joinColumns:
                post_id:
                    referencedColumnName: id
            inverseJoinColumns:
                category_id:
                    referencedColumnName: id
        cascade:  ["persist"]

This is manyTomany from category.orm.yml

manyToMany:
    posts:
        targetEntity: MyBundle\Entity\Post
        mappedBy: categories
        joinTable:
            name: posts_categories
            joinColumns:
                post_id:
                    referencedColumnName: id
            inverseJoinColumns:
                category_id:
                    referencedColumnName: id

I will really appreciate if you can let me know what I am doing wrong here.

Hello There,

Is it possible to set multiple ManToMany Relationships on the same Model/Entity. For Example, considering the current scenario, I may have multiple hosts and multiple attendees to an event. In this case, would i need the above or there is some better option, Thanks in advance.