php - laravel eloquent relation one to many returns null

Question

The product data always return null when i get the incoming_goods data (belongsTo).

Here is my Product Model:

<?php

namespace App;

use IlluminateDatabaseEloquentModel;
use IlluminateDatabaseEloquentSoftDeletes;

class Product extends Model
{
    use SoftDeletes;

    protected $guarded = [
        'id', 'created_at', 'updated_at', 'deleted_at',
    ];

    public function transaction_details()
    {
        return $this->hasMany('AppTransaction_detail');
    }

    public function incoming_goods()
    {
        return $this->hasMany('AppIncoming_good');
    }       
}

Here is my Incoming_good Model:

<?php

namespace App;
use IlluminateDatabaseEloquentModel;

class Incoming_good extends Model
{
    protected $guarded = [
        'id', 'created_at', 'updated_at',
    ];

    public function product()
    {
        return $this->belongsTo('AppProduct');
    }       
}

And here is my migration of that two table:

products table Migration:

<?php

use IlluminateSupportFacadesSchema;
use IlluminateDatabaseSchemaBlueprint;
use IlluminateDatabaseMigrationsMigration;

class CreateProductsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('products', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name', 50);
            $table->integer('price');
            $table->integer('stock')->nullable();
            $table->integer('available');
            $table->string('image1', 190)->nullable();
            $table->string('image2', 190)->nullable();
            $table->string('image3', 190)->nullable();
            $table->string('image4', 190)->nullable();
            $table->string('image5', 190)->nullable();
            $table->timestamps();
            $table->softDeletes();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('products');
    }
}

incoming_goods migration:

<?php

use IlluminateSupportFacadesSchema;
use IlluminateDatabaseSchemaBlueprint;
use IlluminateDatabaseMigrationsMigration;

class CreateTableIncomingGoods extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('incoming_goods', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('product_id');
            $table->integer('stock');
            $table->text('note')->nullable();
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('incoming_goods');
    }
}

Here is my code to show incomong_goods data and product (relation belongsTo):

$data = Incoming_good::select('id', 'stock', 'note', 'created_at')->with('product')->get();

I've try to use alies, but still it return the product data null. Hope you can help me :)

Answer 1

In order to match up the eager loaded Products with the Incoming_goods, Laravel needs the foreign key to be selected. Since you did not include the foreign key (product_id) in the select list, Laravel can't match up the related records after retrieving them. So, all your product relationships will be empty. Add in the foreign key to the select list, and you should be good.

$data = Incoming_good::select('id', 'product_id', 'stock', 'note', 'created_at')
    ->with('product')
    ->get();