Cakephp 3 belongsToMany association is not updating junction table

Need Help
1

I have 4 tables: products, tags, categories and taxonomy_to_products. The table contains data that links tags and products together, same with category and products.

When I am trying to link existing category to products it’s not updating on the taxonomy_to_products table.

Here is my taxonomy_to_products table screenshot

enter image description here

Model\Table\CategoriesTable:-

$this->belongsToMany('Products', [
        'targetForeignKey' => 'product_id',
        'foreignKey' => 'category_id',
        'joinTable' => 'taxonomy_to_products',
        'saveStrategy' => 'replace'
    ]);

Model\Table\TagsTable:-

$this->belongsToMany('Products', [
        'targetForeignKey' => 'product_id',
        'foreignKey' => 'tag_id',
        'joinTable' => 'taxonomy_to_products',
        'saveStrategy' => 'replace'
    ]);

Model\Table\ProductsTable:-

$this->belongsToMany('Tags', [
        'foreignKey' => 'product_id',
        'targetForeignKey' => 'tag_id',
        'joinTable' => 'taxonomy_to_products',
        'saveStrategy' => 'replace'
    ]);
    $this->belongsToMany('Categories', [
        'foreignKey' => 'product_id',
        'targetForeignKey' => 'category_id',
        'joinTable' => 'taxonomy_to_products',
        'saveStrategy' => 'replace'
    ]);

Model\Table\TaxonomyToProducts:-

$this->belongsTo('Categories', [
        'foreignKey' => 'category_id',
        'joinType' => 'INNER'
    ]);
    $this->belongsTo('Tags', [
        'foreignKey' => 'tag_id',
        'joinType' => 'INNER'
    ]);
    $this->belongsTo('Products', [
        'foreignKey' => 'product_id',
        'joinType' => 'INNER'
    ]);

This is my action

public function edit($id = null) {
    $product = $this->Products->get($id, [
        'contain' => [
            'Media' => ['fields' => ['id', 'url']],
            'Categories',
            'Tags',
        ]
    ]);
    if ($this->request->is(['patch', 'post', 'put'])) {
        $product = $this->Products->patchEntity($product, $this->request->getData(), ['associate' => ['Categories']]);
        //print_r($$product);exit();
        if ($this->Products->save($product)) {
            $this->Flash->success(__('The product has been saved.'));

            return $this->redirect(['action' => 'index']);
        }
        $this->Flash->error(__('The product could not be saved. Please, try again.'));
    }
    $allCategories = $this->Products->Categories->find('treeList', [
                'keyPath' => 'id',
                'valuePath' => 'name',
                'spacer' => '⚊',
            ])->toArray();
    $this->set(compact('product', 'allCategories'));
}

This is my Form:-

<?= $this->Form->select('categories._ids', $allCategories, ['hiddenField' => false, 'multiple' => 'checkbox', 'escape' => false])?>
2

You should fullfile naming conventions, table should be called tags_products. Also table isn´t well designed, category_id should be in products table. Or if it´s true, that products has and belongs to many categories (I´m not sure about it) you should create another table categories_products to join categories and products.