cakephp 3 save empty belongsToMany relation

Question

I have a Shops table which can have Products. Other Shops can have the same Products so I used a belongsToMany relation table ShopsProducts.

I can add an infinite number of Products to a Shop and remove them by saving the Shop entity including the relation. All works fine, but if I want to unlink all Products from a Shop in my form and save, the relation is of cause empty so the Shop will always have 1 Product that I can't delete over the relation but only directly.

This is what the request looks like from the Shops form with a Product

data => [
    'name' => 'some',
    'is_active' => '1',
    'slug' => 'some',
    'product_id' => '',
    'products' => [
        (int) 5 => [
            'id' => '5',
            '_joinData' => [
                'priority' => '0'
            ]
        ]
    ],
]

And this is the request without

data => [
    'name' => 'some',
    'is_active' => '1',
    'slug' => 'some',
    'product_id' => '',
]

What is the cake way to handle this issue?

Answer 1

What's your save strategy?

https://book.cakephp.org/3.0/en/orm/saving-data.html#saving-belongstomany-associations

Try replace instead of append.

If that doesn't work for you, check in the before() or afterSave() if products->get('products') is empty, if it is manually call a deleteAll() on the join table for that product an shop.

Answer 2

You will need to set your association to [] to blank it out.

$shops->products = [];

$shops->setDirty('products ', true);