Laravel 模型不起作用

Question

我正在尝试创建带有评论的帖子页面；但是，当我将评论添加到帖子时它不起作用，因为系统无法识别帖子 ID。我做错了什么，它不知道 post_id 等于 $post_id

我收到以下错误：

SQLSTATE[HY000]: General error: 1364 Field 'post_id' does not have a default value (SQL: insert into comments( body, updated_at, created_at) values (This is a test comment, 2017-08-15 19:51:47, 2017- 08-15 19:51:47))

意见表

 <div class="well">
    <h4>Leave a Comment:</h4>

    <form role="form" method="post" action="{{ $post->id }}/comments">
    {{  csrf_field() }}

       <div class="form-group">
          <textarea name="body" class="form-control" rows="3"></textarea>
       </div>

       <button type="submit" class="btn btn-primary">Submit</button>
    </form>
 </div>

路线

Route::post('/posts/{post}/comments', 'CommentController@store');

控制器

public function store(Post $post)
{
    $post->addComment(request('body'));

    return back();
}

评论模型

class Comment extends Model
{
    protected $fillable = ['body'];

    public function post()
    {
        return $this->belongsTo(Post::class);
    }
}

后模型

class Post extends Model
{
    public function addComment($body)
    {
        Comment::create([
            'body' => $body,
            'post_id' => $this->id
        ]);
    }

    public function comments()
    {
        return $this->hasMany(Comment::class);
    }
}

Answer 1

post_id 不在可填充数组中：

class Comment extends Model
{
    protected $fillable = ['body', 'post_id']; //<---
    ...
}