Insertion with relationship N:N

Question

I have these text inputs, in a way people can choose to fill them or not. Or just fill in some of them. I send the data from this form via Xios in an array (I don’t know if it’s the best way, so I’m here doing this post). Explaining further, this form would be the taxes(Taxes) which is part of a product form(Products).

And for this I create 3 tables in the Standard. A table for Products, another to the Taxes_names a pivot table, relating the id of both but with an additional field, which in this case is the value, that would store the value placed in those input text.

In the Laravel, I request this array as follows.

$taxes = $request -> taxes;

The interface is mounted and correct. I can enter the data via quiet database and do a debug, etc.

Pivot table product_taxes: id | product_id |taxes_id

Let’s say on the table taxes_name has the following data:

id | name |
-----------------------
1  | cfop |
2  | cst/csosn icms|
3  | cst pis(danfe)|
4  | cst cofins(danfe)|

My problem is, how will I pull the ids correctly from this table and move to the pivot table, along with these filled Forms.

Model da class Products:

public function taxes()
{
    return $this->belongsToMany('App\TaxesNames', 'product_taxes', 'product_id', 'taxes_id')->withPivot('value');

}

Array received in the Laravel

array (
    'cfop' => '12',
    'cst' => '2',
    'cstPis' => '3',
    'cstCofins' => '4',
  )

Xios:

           this.axios.post('http://chart.solutions/public/api/produto', {
                nome: this.nome, 
                codigo: this.codigo, 
                preco: this.preco,
                group: this.selectedgroup,
                subgroup: this.selectedsubgroup,
                taxes: this.taxes
            })
            .then((response) => {
                if(response.data.success){
                    this.clearForm()
                    this.productSwal("success")
                    console.log(this.taxes)
                }
            })
            .catch((error) => {
                    this.productSwal("error") 
            });