How to save query parameters to the database

I have a form which calls the checkOut function upon submission:

<form [formGroup]="submitForm" (ngSubmit)="checkOut(items)">
<input type="submit" value="Check Out">
</form>

The form submission leads to the form carrying over the query parameters:

public checkOut(items: any)  {
this.router.navigate(['check-out'], { queryParams: { checkouts: JSON.stringify(this.items) } });
}
 this.route.queryParams.subscribe(params => {
    this.checkouts = params['checkouts'];
		 this.objectValues = {...this.checkouts};
		 }

Then I can add the query parameters to the database like this:

this.checkouts = params['checkouts'];
this.object = Object.assign({}, ...this.checkouts);
	 
create_NewCheckOut(record) {
return this.firestore.collection('Checkouts').add(this.object);
}

this.create_NewCheckOut(this.object).then(resp => {      
    
    this.checkoutProductName = "";
      this.checkoutQuantity = undefined;
      this.checkoutProductPrice = undefined;
    })
      .catch(error => {
        console.log(error);
      });
  });                                                                                                                                                                                                                   
                                                                                                            
 this.arrayToObject2 = JSON.parse( JSON.stringify( this.checkouts ) ); 
  
<div *ngFor="let out of arrayToObject2">
<h5>Product Name: {{out.product_name}}</h5>
<h6>quantity: {{out.quantity}} </h6>
<p>Price: {{out.product_price}}</p>
</div>

But alas no data was added to the database.