How to use relationship in laravel? - laravel

Question

I use work with relationship in laravel 5.6.
I create product table with migration:
Schema::create('products', function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->string('slug');
$table->text('description');
$table->string('tags');
$table->string('original_price');
$table->integer('view_order')->default(0);
$table->unsignedInteger('admin_id');
$table->foreign('admin_id')->references('id')->on('admins');
$table->boolean('status');
$table->timestamps();
});
And i create category table with migration:
Schema::create('categories', function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->boolean('status');
$table->timestamps();
});
And create product_categories table with migration:
Schema::create('product_categories', function (Blueprint $table) {
$table->increments('id');
$table->unsignedInteger('product_id');
$table->foreign('product_id')->references('id')->on('products');
$table->unsignedInteger('category_id');
$table->foreign('category_id')->references('id')->on('categories');
$table->timestamps();
});
Now, I use Bootstrap Multiselect for categories in one product.
In category model:
/**
* #return \Illuminate\Database\Eloquent\Relations\BelongsToMany
*/
public function products()
{
return $this->belongsToMany(Product::class);
}
In Product model:
/**
* #return \Illuminate\Database\Eloquent\Relations\BelongsToMany
*/
public function categories()
{
return $this->belongsToMany(Category::class);
}
How to add category_id and product_id in product_categories table with relationship?

Answer 1

Check the documantation related to Many to many Relationships.
Your pivot table doesn't follow Laravel's convention, either update your table name or update your relationships to address this issue.
The convention is the alphabetical order of the two models, thus your pivot table should be named: category_product
If you do not want to update the table name, update your relationships.
public function categories()
{
return $this->belongsToMany(Product::class, 'product_categories')
}
public function products()
{
return $this->belongsToMany(Category::class, 'product_categories')
}
Now to "save an entry to the pivot table" -or in other words: to create the relationship between the two models- you may use attach or sync method.
$product->categories()->attach($category);
$product->categories()->attach([$categoryId1, $categoryId2]);
sync is different.
The sync method accepts an array of IDs to place on the intermediate table. Any IDs that are not in the given array will be removed from the intermediate table.
To detach (delete entry in pivot table), simple use the detach method.
$product->categories()->detach([1, 2]);
Of course, do the same for Category.

Answer 2

Your model names are Product and Category and the derived relational table will be category_product because category came before product in alphabetical order.
You only have to add the pivot table:
public function categories()
{
return $this->belongsToMany(Product::class, 'product_categories')
}
public function products()
{
return $this->belongsToMany(Category::class, 'product_categories')
}
Now for save with relationship:
$product->categories()->attach($category);
$product->categories()->attach([$category_id_1, $category_id_2]);

Answer 3

You only have to add the pivot table:
public function products()
{
return $this->belongsToMany(Product::class, 'product_categories');
}
public function categories()
{
return $this->belongsToMany(Category::class, 'product_categories');
}

Answer 4

By default, laravel derives the table name from the alphabetical order of the related model names. Here your model names are Product and Category and the derived relational table will be category_product because category came before product in alphabetical order. Either you can change the table name or you can override this my mentioning the table name as the second parameter in the relational method as follows.
public function products()
{
return $this->belongsToMany(Product::class, 'product_categories');
}
public function categories()
{
return $this->belongsToMany(Category::class, 'product_categories');
}