Eloquent foreign key - mysql

Question

I am trying to make a 3 models relationship in Laravel 6 and Foreign keys won't work, becouse i get this error:
Illuminate/Database/QueryException with message 'SQLSTATE[42S22]: Column not found: 1054 Unknown column 'products.product_id' in 'where clause' (SQL: select * from `products` where `products`.`product_id` = 1 and `products`.`product_id` is not null limit 1)'
I have a 3 table (the tables are: users, cartItems, products) relationship . The foreign key that refers user's id into cartItems seamns to work, but the one that refers product's id into cartItems don't .
The cartItems table migration:
Schema::create('cart_items', function (Blueprint $table) {
$table->id();
$table->unsignedBigInteger('user_id');
$table->unsignedBigInteger('product_id');
$table->timestamps();
$table->foreign('product_id')->references('id')->on('products');
});
The products table migraton:
Schema::create('products', function (Blueprint $table) {
$table->id();
$table->string('productName');
$table->text('description');
$table->integer('price');
$table->string('image');
$table->timestamps();
});
The cartItem model:
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class cartItem extends Model
{
public function user() {
return $this->belongsTo(User::class);
}
public function product() {
return $this->hasOne(Product::class, 'product_id');
}
}
The product model:
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Product extends Model
{
protected $guarded = [];
public function cartItem() {
return $this->belongsToMany(Product::class);
}
}
The user model:
<?php
namespace App;
use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Notifications\Notifiable;
class User extends Authenticatable
{
use Notifiable;
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'name', 'email', 'password',
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
'password', 'remember_token',
];
/**
* The attributes that should be cast to native types.
*
* #var array
*/
protected $casts = [
'email_verified_at' => 'datetime',
];
public function cartItems() {
return $this->hasMany(cartItem::class);
}
}

Answer 1

$table->foreign('product_id')->references('id')->on('products');
expects the products table to be created already. Migrations run in filename order, so make sure your products table migration has an earlier "date" stamp than the cart_items table migration.

Answer 2

If you are specifying xxxxx_id columns in the cartItems table, then cartItem is the child model, not the parent. Otherwise you might need to rethink your relationships.
To fix as-is (and leave the migration the same), change your Eloquent relationships to:
// Product.php
public function cartItems() {
return $this->hasMany(cartItem::class);
}
and its inverse:
// cartItem.php
public function product() {
return $this->belongsTo(Product::class);
}