Laravel空对象hasMany关系

Question

SOLVED i should not have called out my attributes in the models. For some reason this was keeping it from working.

I have the following structure of two models, Listing and Image. Table Images has FK listing_id that references id on table Listing.

My Eloquent Model for Listing:

namespace App\Models;

use Illuminate\Database\Eloquent\Model as Model;

class Listing extends Model {

    protected $table = 'listings';
    protected $connection = 'mysql';

    public $id;
    public $name;
    public $value;
    public $itemDescr;
    public $user_id;
    public $category_id;

    protected $fillable = [
        'id',
        'name',
        'value',
        'itemDescr',
        'user_id',
        'category_id'
    ];

    /**
     * Return images
     *
     * @return \Illuminate\Database\Eloquent\Relations\HasMany
     */
    public function images()
    {
        return $this->hasMany('App\Models\Image');
    }

}

My Eloquent Model for Image:

namespace App\Models;
use Illuminate\Database\Eloquent\Model as Model;

class Image extends Model
{
    protected $table = 'images';
    protected $connection = 'mysql';

    public $id;
    public $imageType;
    public $title;
    public $filename;
    public $path;
    public $author_id;
    public $listing_id;
    public $user_id;
    public $size;
    public $width;
    public $height;


    protected $fillable = [
        'imageType',
        'title',
        'filename',
        'path',
        'author_id',
        'listing_id',
        'user_id',
        'size',
        'width',
        'height'
    ];

    /**
     *
     * @return \Illuminate\Database\Eloquent\Relations\BelongsTo
     */
    public function listings()
    {
        return $this->belongsTo('App\Models\Listing', 'listing_id');
    }

}

My controller:

/**
 * Return the full list of listings
 *
 * @param Request $request
 *
 * @return string
 */

    public function itemList(Request $request)
    {
        $listings = Listing::with('images')->get();

        return $listings;

    }

I cannot seem to return my listing WITH the image objects -- they are always null. Here is a sample response:

{ id: 6, name: "rare listing item", value: "100", itemDescr: "this is a descr", user_id: 1, category_id: 6, created_at: "2016-05-30 13:47:33", updated_at: "2016-05-30 13:47:33", images: [ ] }

The database shows two images with listing_id of 6 for this particular item. I cannot figure out what could be wrong, I've tried nearly all suggestions. Any ideas?

Answer 1

In Laravel table columns and their values is held in $attributes property, Laravel uses __get() magic method to get the $attributes data. By defining public $listing_id as property on your model it just like telling Laravel: "Hey this is the listing_id and not the one that held $attributes property so please return this instead".

When you define the relationship:

return $this->belongsTo('App\Models\Listing', 'listing_id', 'id');

The public $listing_id property will be returned which is the value is null . Remove those public property definition and it should be works.