laravel 刀片模板和雄辩的模型——如何在许多关系中获取第一个元素

Question

我有以下雄辩的模型（删除代码以简化此问题）。我正在尝试获取第一张图片

class Design extends Model
{
    use SoftDeletes;

    protected $guarded = ['id','tags','keywords'];

    public function images()
    {
        return $this->hasMany(DesignImage::class);
    }
   ...
}

class DesignImage extends Model
{
    use SoftDeletes;

    public function design()
    {
        return $this->belongsTo(Design::class);
    }
}

然后我将以下代码传递给刀片模板

$data['designs'] = Design::where('quantity','>',0)->get();
return view('mailings.form',$data);

模板（工作正常；我得到所有图像的名称

@foreach($design->images as $image)
    {{ $image->name }}
@endforeach

但如果我尝试

{{ $design->images->first()->name }}

我得到 Trying to get property 'name' of non-object`

如果我尝试

{{ $design->images[0]->name }}

我得到未定义的偏移量：0

如果我这样做了

@json ($design->images->first())

我得到（有效）

{"id":1,"name":"Image 1 Design 1","thumb":"images/main_thumb.jpg","image":"images/main_large.jpg","design_id":1 ,"created_at":"2018-12-11 20:10:03","updated_at":"2018-12-11 20:10:03","deleted_at":null}

如何获得刀片模板中的第一张图片？为什么我得到这个奇怪的输出？

Answer 1

发生错误是因为最新的$design 没有image。试试这个代码

@foreach($designs as $design)
    // your code
    @php
        $firstImage = $design->images()->first();
    @endphp
    {{ !empty($firstImage->name) ? $firstImage->name : ''}}
    // other part ofcode
@endforeach

您也可以使用控制器优化此代码

$data['designs'] = Design::where('quantity','>',0)->with('images')->get();
return view('mailings.form',$data); 

在视图中

@foreach($designs as $design)
    // your code
    @php
        $firstImage = $design->images->first();
    @endphp
    {{ !empty($firstImage->name) ? $firstImage->name : ''}}
    // other part ofcode
@endforeach