如何检查图像是否存在，否则显示其他内容 Laravel 5.2.

我需要检查我的横幅是否存在动态填充的图像，用户可以上传，如果用户没有上传横幅图像，那么我想显示其他内容，例如默认图像。

这是我展示的图像横幅。

@foreach ($flyer->bannerPhotos as $photo)
    <img src="/travel/{{ $photo->thumbnail_path }}" alt="{{ $flyer->owner->username }}" data-id="{{ $photo->id }}" id="Banner-image">
@endforeach

我尝试做"file_exists"，如果$photo==''，则显示其他内容，但它不起作用。你们中有人知道这样做的方法吗？

***********编辑************

TravelFlyerController.php（缩短）

<?php
namespace App'Http'Controllers;
use App'User;
use App'Flyer;
use App'FlyerPhoto;
use App'FlyerBanner;
use App'Http'Requests;
use Illuminate'Http'Request;
use App'Http'Controllers'Controller;
use Illuminate'Support'Facades'Auth;
use App'Http'Requests'FlyerPhotoRequest;
use App'Http'Requests'FlyerBannerRequest;
use App'Http'Requests'TravelFlyersRequest;
class TravelFlyersController extends Controller {
    /**
     * Add banner photo to a flyer.
     *
     * @param $title
     * @param FlyerBannerRequest $request
     */
    public function addBannerPhoto($title, FlyerBannerRequest $request) {
        // create a new photo instance from a file upload
        $photo = FlyerBanner::fromFile($request->file('photo'))->upload();
        // Set Flyer::LocatedAt() in (Flyer.php Model)
        // = to the title, and add the banner photo.
        // -- Find the flyer and add the banner photo.
        Flyer::LocatedAt($title)->addBannerPhoto($photo);
    }

传单横幅.php型号：

<?php
namespace App;
use Image;
use Illuminate'Database'Eloquent'Model;
use Symfony'Component'HttpFoundation'File;
use Symfony'Component'HttpFoundation'File'UploadedFile;
class FlyerBanner extends Model {
    /**
     * @var string
     */
    protected $table = "flyer_banner";
    /**
     * @var array
     */
    protected $fillable = ['name', 'path', 'thumbnail_path'];
    /**
     * @var
     */
    protected $file;
    /**
     * @var
     */
    protected $name;

    /**
     * A banner photo belongs to a flyer.
     *
     * @return 'Illuminate'Database'Eloquent'Relations'BelongsTo
     */
    public function flyer() {
      return $this->belongsTo('App'Flyer');
    }

    /**
     * Make a new instance from an uploaded file.
     *
     * @param UploadedFile $file
     * @return static
     */
    public static function fromFile(UploadedFile $file) {
        // Make new instance of photo.
        $photo = new static;
        // Assign the Uploaded file to the $file object.
        $photo->file = $file;
        // Set $photo to the fill properties, which are
        // the name, path, and thumbnail path of a photo.
        $photo->fill([
            'name' => $photo->setFileName(),
            'path' => $photo->filePath(),
            'thumbnail_path' => $photo->thumbnailPath()
        ]);
        // return the photo
        return $photo;
    }

    /**
     * Get the banner photos base directory.
     */
    public function baseDir() {
        return 'src/public/FlyerBanner/photos';
    }

    /**
     * Get the name and extension of the banner photo.
     *
     * @return string
     */
    public function setFileName() {
        // Get the file name original name
        // and encrypt it with sha1
        $hash = sha1 (
            $this->file->getClientOriginalName()
        );
        // Get the extension of the photo.
        $extension = $this->file->getClientOriginalExtension();
        // Then set name = merge those together.
        return $this->name = "{$hash}.{$extension}";
    }

    /**
     *  Return the full file path of the banner photo, with the name.
     *
     * @return string
     */
    public function filePath() {
        return $this->baseDir() . '/' . $this->name;
        // Ex: 'BannerPhoto/photos/foo.jpg'
    }

    /**
     * Return the full file thumbnail path of the banner photo, with the name.
     *
     * @return string
     */
    public function thumbnailPath() {
        return $this->baseDir() . '/tn-' . $this->name;
        // Ex: 'BannerPhoto/photos/tn-foo.jpg'
    }

    /**
     * Upload the file to the proper directory.
     *
     * @return $this
     */
    public function upload() {
        // move a file to the base directory with the file name.
        $this->file->move($this->baseDir(), $this->name);
        // Make the thumbnail.
        $this->makeThumbnail();
        return $this;
    }

    /**
     * Function to make the actual thumbnail.
     * -- make and save reference the Image intervention library, not Eloquent. --
     */
    protected function makeThumbnail() {
        Image::make($this->filePath())
            ->fit(2000, 800)
            //->resize(null, 400, function ($constraint) {
             //   $constraint->aspectRatio();
             //   $constraint->upsize();
            //})
            ->save($this->thumbnailPath());
    }

    /**
     * Delete the banner photo path and thumbnail path in DB.
     * Access the delete function in FlyerController@destroyBannerPhoto method
     */
    public function delete() {
        $image = $this->path;
        $thumbnail_image = $this->thumbnail_path;
        'File::delete([
            $image,
            $thumbnail_image
        ]);
        parent::delete();
    }
}

传单照片横幅上传表格：

<form action="/travel/{{ $flyer->title }}/banner" method="post" class="dropzone" id="addBannerForm" enctype="multipart/form-data">
  {{ csrf_field() }}
</form>

我的路线：

Route::group(['middleware' => ['web']], function () {
    /** Resource Route For Travel Flyers */
    Route::resource('travelflyers', 'TravelFlyersController');
    /** Show a Flyer. **/
    Route::get('{title}', 'TravelFlyersController@show');
   
    /** Add a photo banner to a flyer **/
    Route::post('{title}/banner', 'TravelFlyersController@addBannerPhoto');
    /** Delete Flyer Banner photo **/
    Route::delete('photo/{id}', [
        'uses' => ''App'Http'Controllers'TravelFlyersController@destroyBannerPhoto',
        'as'   => 'flyer.delete.banner',
    ]);
});