Question

我有一个关于laravel的一对多关系的问题。

我正在尝试根据此页面制作程序。 https://manablog.org/laravel_bulletin_board/

我的节目在这里。

class PostsController extends Controller
{
  public function index()
  {
      \DB::enableQueryLog();
      $comments = Post::find(9)->comments;
      $query = \DB::getQueryLog();

      Log::debug($query);

      $posts = Post::all();
      $query = \DB::getQueryLog();
      Log::debug($query);

      return view('bbc.index')->with('posts', $posts);
  }
}
class Post extends Model {

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

    public function comments(){
        return $this->hasMany('App\Comment','post_id', 'id');
    }


}
class Comment extends Model{

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

    public function post() {
        return $this->belongsTo('App\Post');
    }

}

表格在这里。

mysql> desc comments;
+------------+------------------+------+-----+---------+----------------+
| Field      | Type             | Null | Key | Default | Extra          |
+------------+------------------+------+-----+---------+----------------+
| Id         | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| post_id    | int(10) unsigned | NO   | MUL | NULL    |                |
| name       | varchar(50)      | NO   |     | NULL    |                |
| content    | varchar(300)     | NO   |     | NULL    |                |
| created_at | timestamp        | YES  |     | NULL    |                |
| updated_at | timestamp        | YES  |     | NULL    |                |
+------------+------------------+------+-----+---------+----------------+
6 rows in set (0.00 sec)

mysql> desc posts;
+------------+------------------+------+-----+---------+----------------+
| Field      | Type             | Null | Key | Default | Extra          |
+------------+------------------+------+-----+---------+----------------+
| Id         | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| name       | varchar(50)      | NO   |     | NULL    |                |
| title      | varchar(50)      | NO   |     | NULL    |                |
| content    | varchar(300)     | NO   |     | NULL    |                |
| created_at | timestamp        | YES  |     | NULL    |                |
| updated_at | timestamp        | YES  |     | NULL    |                |
+------------+------------------+------+-----+---------+----------------+
6 rows in set (0.00 sec)

但是我的计划没有按照我的预期运作。然后我检查了日志。日志在这里。

[2017-08-31 18:25:47] local.DEBUG: array (
  0 =>
  array (
    'query' => 'select * from `posts` where `posts`.`id` = ? limit 1',
    'bindings' =>
    array (
      0 => 9,
    ),
    'time' => 4.5099999999999998,
  ),
  1 =>
  array (
    'query' => 'select * from `comments` where `comments`.`post_id` is null and `comments`.`post_id` is not null',
    'bindings' =>
    array (
    ),
    'time' => 0.53000000000000003,
  ),
)

没有关系。而且我无法理解为什么从comments comments选择* post_id。comments为空且post_id。std::ifstream inFile(file, std::ios::binary); if (!inFile.is_open() || !inFile.good()) {COUT "Error opening file\n"; return false; } inFile >> script; // Here, it is skipping whitespaces, script is an std::string不为空＆＃39;在这儿。这是什么问题？

Answer 1

我认为问题是因为您的ID列是Id而不是id。

MySQL本身不区分大小写，但PHP不是。

你可以：

将数据库中的Id更改为id（如果适用，还会迁移迁移文件）

或

将以下内容添加到您的模型中：

protected $primaryKey = 'Id';

并将您的关系更改为：

public function comments() {
    return $this->hasMany('App\Comment');
}
//or
public function comments() {
    return $this->hasMany('App\Comment', 'post_id', 'Id');
}

希望这有帮助！

一对多关系不起作用

1 个答案: