Laravel数据透视表

Question

So im trying to do a pivot table for "order" and "item". but im getting a SQL error

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'orderline.order_order_id' in 'field list' (SQL: select `item`.*, `orderline`.`order_order_id` as `pivot_order_order_id`, `orderline`.`item_item_id` as `pivot_item_item_id`, `orderline`.`quantity` as `pivot_quantity` from `item` inner join `orderline` on `item`.`item_id` = `orderline`.`item_item_id` where `orderline`.`order_order_id` in (1, 2, 3, 4, 5))

the only thing i can notice off the bat is "order_order_id" should be "order_id" and "item_item_id" "item_id" but im not sure.

i get this error when calling

$customers = Customer::with('orders.items')->get();
dd($customers);

Here is my models

class Customer extends Model
{

public $timestamps = false;
protected $table = "customer";
protected $primaryKey = "customer_id";

public function orders(){
    return $this->hasMany('App\Order','customer_id');
}
}

class Order extends Model
{
/**
 * @var bool
 */
public $timestamps = false;
protected $table = "order";
protected $primaryKey = "order_id";

public function customer(){
    return $this->hasOne('App\Customer','customer_id');
}

public function items(){
    return $this->belongsToMany('App\Item','orderline')->withPivot('quantity');
}

}


class Item extends Model
{
/**
 * @var bool
 */
public $timestamps = false;

protected $table = "item";
protected $primaryKey = "item_id";

public function orders(){
    return $this->belongsToMany('App\Order','orderline')->withPivot('quantity');
}

public function stock(){
    return $this->hasOne('App\Stock','item_id');
}

}

Here is my migrations and foreign key constraints

Order:

public function up()
{
    Schema::create('order', function (Blueprint $table) {
        $table->increments('order_id');
        $table->integer('customer_id')->unsigned();
        $table->date('date_placed');
        $table->date('date_shipped');
        $table->decimal('shipping_charge',7,2);
    });
   }

Item:

public function up()
{
    Schema::create('item', function (Blueprint $table) {
        $table->increments('item_id');
        $table->string('description',64);
        $table->decimal('cost_price',7,2);
        $table->decimal('sell_price',7,2);
    });
}

Orderline:

public function up()
{
    Schema::create('orderline', function (Blueprint $table) {
        $table->integer('order_id')->unsigned();
        $table->integer('item_id')->unsigned();
        $table->integer('quantity');
        $table->primary(['order_id','item_id']);
    });
}

FkConstraintToOrder:

public function up()
{
    Schema::table('order', function (Blueprint $table) {
        $table->foreign('customer_id')->references('customer_id')->on('customer')->onDelete('cascade');
    });
}

FkConstraintToOrderline:

public function up()
{
    Schema::table('orderline', function (Blueprint $table) {
        $table->foreign('order_id')->references('order_id')->on('order')->onDelete('cascade');
        $table->foreign('item_id')->references('item_id')->on('item')->onDelete('cascade');
    });
}

I think I'm missing something but I'm not sure what. Any help would be appreciated.

Answer 1

While you can name your pivot table whatever you want, according to the official Laravel documentation at https://laravel.com/docs/5.5/eloquent-relationships you should name it based on the two tables it is connecting in alphabetical order, in this case item_order. Doing so will make your code simpler and easier to read.

As to your question, the way Laravel determines the name of the columns in the pivot table is based on the primary key of the two tables in question and prepends the name of the class to the front, so since your primary key is order_id because of protected $primaryKey = "order_id"; it takes that and adds the name of the class, so it calls it order_order_id. You can override this functionality by doing something like this:

return $this->belongsToMany('App\Item', 'orderline', 'order_id', 'item_id');

Usually the primary key is just id , so the key that Laravel would look for would be order_id .