当我尝试设置编辑功能时，属性[id]在此集合实例中不存在

Question

我明白了：

  

ErrorException（E_ERROR）   属性[id]在此集合实例中不存在。

我一直在环顾四周，我尝试了几种不同的修复方法，但仍然没有找到答案。到目前为止，这就是我的意思。。。我找不到导致问题的原因，所以我几乎不需要帮助...

PostsController.php

public function edit($id)
{
    $post = Post::find($id);
    $categories = Category::all();
    $cats = array();
        foreach ($categories as $category){
            $cats[$category->id] = $category->title;
            }

    return view('posts.edit')->withPost($post)->withCategories($cats);
}

edit.blade.php

{!! Form::model($post, ['route' => ['PostsController@update', $post->id], 'method' => 'PUT']) !!}
                         <div class="col-md-4">           
                                    <div class'form-group'>
                                        {{ Form::label('title', 'Title')}}
                                        {{ Form::text('title', $post->title, ['class' => 'form-control', 'placeholder' => 'Title'])}}
                                    </div>
                         </div>

                         <div class="col-md-4">           
                                    <div class'form-group'>
                                        {{ Form::label('slug', 'Slug')}}
                                        {{ Form::text('slug', $post->slug, ['class' => 'form-control ', 'placeholder' => 'Slug', 'required' =>'', 'minlength' => '5', 'maxlength' => '255'])}}
                                    </div>
                         </div>

                         <div class="col-md-4">
                                    <div class'form-group'>
                                        {{ Form::label('category_id', 'Category :')}}
                                        {{ Form::select('category_id', $categories, $post->categoty_id, ['class' => 'form-control']) }}
                                    </div>
                         </div>
                 </div>

            <div class="row post_row">
                <div class="col-md-8">
                            <div class'form-group'>
                                {{ Form::label('body', 'Body')}}
                                {!! Form::textarea('body', '$post->body', ['id' => 'article-ckeditor', 'class' => 'form-control space', 'placeholder' => 'Body Text'])!!}
                            </div>
                </div>
           </div>

                    <div class'form-group' style="padding-top: 20px">
                     {{Form::submit('Submit', ['class'=>'btn btn-primary'])}}
                     {!! Form::close() !!}
                     </div>