Why is eloquent looking for another pivot table?

Question

Laravel

Hello. There are two models

class Product extends Model
{
    public function categories(){
        return $this->belongsToMany('App\Category');
    }
}

and

class Category extends Model
{
    public function children(){
        return $this->hasMany(self::class, 'parent_id');
    }
}

As well as migrations with a pivot table

class CreateProductCategoryTable extends Migration
{
    public function up()
    {
        Schema::create('product_category', function (Blueprint $table) {
            $table->BigIncrements('id');
            $table->BigInteger('product_id')->unsigned();
            $table->BigInteger('category_id')->unsigned();
            $table->timestamps();
        });

        Schema::table('product_category', function (Blueprint $table) {
            $table->foreign('product_id')->references('id')->on('products')
                ->onDelete('cascade')->onUpdate('cascade');
            $table->foreign('category_id')->references('id')->on('categories')
                ->onDelete('cascade')->onUpdate('cascade');
        });
    }

    public function down()
    {
        Schema::table('product_category', function (Blueprint $table){
            $table->dropForeign('product_category_product_id_foreign');
            $table->dropForeign('product_category_category_id_foreign');
        });
        Schema::dropIfExists('product_category');
    }

When trying to assign a category to a product using this code,

public function store(Request $request)
    {
        $product = Product::create($request->except('categories'));

        if($request->has('categories')){
            $product->categories()
                ->attach($request->input('categories'));
        }

        return redirect()->route('product.index');
    }

an error occurs

SQLSTATE[42S02]: Base table or view not found: 1146 Table 'test.category_product' doesn't exist (SQL: select `categories`.*, `category_product`.`product_id` as `pivot_product_id`, `category_product`.`category_id` as `pivot_category_id` from `categories` inner join `category_product` on `categories`.`id` = `category_product`.`category_id` where `category_product`.`product_id` = 5) (View: D:\OSPanel\domains\test.local\resources\views\product\_categories.blade.php)

Answer 1

The name of the pivot table is formed from the names of the model tables in alphabetical order - category_product, not product_category

Answer 2

Because you need to read the documentation, which says how Laravel generates the name for the pivot table if it is not explicitly specified in the relationship and how to specify it explicitly if you are not satisfied with how Laravel does it.