學說多對多查詢[語義錯誤]

Question

目前我有以下3個表格。

articles_categories

+-------------+---------+------+-----+---------+-------+ 
| Field  | Type | Null | Key | Default | Extra | 
+-------------+---------+------+-----+---------+-------+ 
| article_id | int(11) | NO | PRI | NULL |  | 
| category_id | int(11) | NO | PRI | NULL |  | 
+-------------+---------+------+-----+---------+-------+ 

類別

+-----------------+--------------+------+-----+---------+----------------+ 
| Field   | Type   | Null | Key | Default | Extra   | 
+-----------------+--------------+------+-----+---------+----------------+ 
| id    | int(11)  | NO | PRI | NULL | auto_increment | 
| title   | varchar(255) | NO |  | NULL |    | 
+-----------------+--------------+------+-----+---------+----------------+ 

文章

+-----------------+--------------+------+-----+---------+----------------+ 
| Field   | Type   | Null | Key | Default | Extra   | 
+-----------------+--------------+------+-----+---------+----------------+ 
| id    | int(11)  | NO | PRI | NULL | auto_increment | 
| title   | varchar(255) | NO |  | NULL |    | 
+-----------------+--------------+------+-----+---------+----------------+ 

在類別實體

/** 
    * @ORM\ManyToMany(targetEntity="Article", mappedBy="categories") 
    * @ORM\OrderBy({"createdAt" = "DESC"}) 
    */ 
    protected $articles; 

In Article實體

/** 
    * All categories this article belongs to. 
    * 
    * @ORM\ManyToMany(targetEntity="Category", inversedBy="articles", cascade={"persist"}) 
    * @ORM\JoinTable(name="articles_categories") 
    */ 
    protected $categories; 

大多數查詢工作正常。但我想獲得屬於某個類別的文章。或者具有特定類別或希望根據類別過濾文章。

爲此我寫下面的查詢。

$em = $this->getEntityManager(); 
     $qb = $em->createQueryBuilder('c'); 
     $qb->select('1') 
      ->from('articles_categories', 'a_c') 
      ->leftJoin('\\Chip\\Entity\\Article', 'a', 'WITH', 'a.id = a_c.article_id') 
      ->leftJoin('\\Chip\\Entity\\Category', 'c', 'WITH', 'c.id = a_c.category_id') 
     ; 

     $result = $qb->getQuery()->getResult(); 

但它會拋出以下錯誤。

[Semantical Error] line 0, col 14 near 'articles_categories': Error: Class 'articles_categories' is not defined. 
500 Internal Server Error - QueryException 
1 linked Exception: QueryException » 

任何幫助或提示或任何更好的方式來編寫查詢將是偉大的。

在此先感謝。

Answer 1

您不應該在查詢生成器中使用表名，而應該使用類名。

$em = $this->getEntityManager(); 
$qb = $em->createQueryBuilder('c'); 
$qb->select('c', 'a') 
    ->from('Chip\Entity\Category', 'c') // this line is not necessary when performing this query in your category repository 
    ->leftJoin('c.articles, a') 
    ->where('c.id = 1'); 
$result = $qb->getQuery()->getResult();