php-如何在学说中定义n-m关系？

如果有一个表“ Article”和一个表“ Tags”.文章可以具有多个标签,标签可以挂在多个文章上.

类BaseArticle如下所示：

abstract class BaseArticle extends Doctrine_Record {
public function setTableDefinition() {
    $this->setTableName('article');
    $this->hasColumn('article_id', 'integer', 8, array(
            'type' => 'integer',
            'length' => 8,
            'fixed' => false,
            'unsigned' => false,
            'primary' => true,
            'autoincrement' => true,
    ));
    $this->hasColumn('title', 'string', null, array(
            'type' => 'string',
            'fixed' => false,
            'unsigned' => false,
            'primary' => false,
            'notnull' => false,
            'autoincrement' => false,
    ));
    $this->hasColumn('text', 'string', null, array(
            'type' => 'string',
            'fixed' => false,
            'unsigned' => false,
            'primary' => false,
            'notnull' => false,
            'autoincrement' => false,
    $this->hasColumn('url', 'string', 255, array(
            'type' => 'string',
            'length' => 255,
            'fixed' => false,
            'unsigned' => false,
            'primary' => false,
            'notnull' => false,
            'autoincrement' => false,
    ));
}

public function setUp() {
    parent::setUp();
    $this->hasMany('Tag as Tags', array( 'local' => 'article_id',
            'foreign'=>'tag_id',
            'refClass'=>'Articletag')
    );
}

}

这样的BaseTag类：

abstract class BaseTag extends Doctrine_Record {
public function setTableDefinition() {
    $this->setTableName('tag');
    $this->hasColumn('tag_id', 'integer', 4, array(
            'type' => 'integer',
            'length' => 4,
            'fixed' => false,
            'unsigned' => false,
            'primary' => true,
            'autoincrement' => true,
    ));
    $this->hasColumn('name', 'string', null, array(
            'type' => 'string',
            'fixed' => false,
            'unsigned' => false,
            'primary' => false,
            'notnull' => false,
            'autoincrement' => false,
    ));
}

public function setUp() {
    parent::setUp();
    $this->hasMany('Article as Articles', array( 'local' => 'tag_id',
            'foreign'=>'article_id',
            'refClass'=>'Articletag')
    );
}

}

和关系类是这样的：

    abstract class BaseArticletag extends Doctrine_Record
{
    public function setTableDefinition()
    {
        $this->setTableName('articletag');
        $this->hasColumn('article_id', 'integer', 8, array(
             'type' => 'integer',
             'length' => 8,
             'fixed' => false,
             'unsigned' => false,
             'primary' => true,
             'autoincrement' => false,
             ));
        $this->hasColumn('tag_id', 'integer', 4, array(
             'type' => 'integer',
             'length' => 4,
             'fixed' => false,
             'unsigned' => false,
             'primary' => true,
             'autoincrement' => false,
             ));
    }

    public function setUp()
    {
        parent::setUp();
    }
}

当我尝试从文章中获取属性时,通过使用以下命令一切顺利：

        $article = Doctrine_Query::create()->from('Article a')
                            ->where('id = ?' , 1)
                            ->fetchOne();
        echo $article->title; //gives me the title

但是当我尝试这个：

        foreach($article->Tags as $tag) {
          echo($tag->name)
        }

我收到一个错误：

Unknown record property / related component "Tags" on "Article"

解决方法:

要建立多对多关系,您必须将关系放在关联表中,而不是联接表中,如下所示：(简化)

Article
...
  Relations:
    Tags:
      class: Tag
      local: article_id
      foreign: tag_id
      refClass: ArticleTag

Tag
...
  Relations:
    Articles:
      class: Article
      local: tag_id
      foreign: article_id
      refClass: ArticleTag

ArticleTag:
(no relations)

然后,您将能够执行诸如$article-> Tags之类的操作.
在Doctrine Documentation中有更多信息.

标签：relationship,doctrine,schema,php
来源： https://codeday.me/bug/20191210/2099487.html