确保与Phalcon相关的nn模型的唯一性

Question

I have a model contents that has a many to many relationship with tags through the intermediary table contents_tags . When I insert a new row in contents I want to also add multiple tags. While this works fine, I want the tags entries to be unique, so they will be inserted if they are new, or updated (although nothing changes) if they already exist.

This unit test seems to imply that this can be done automatically, but I can't manage to replicate the same behaviour. If I don't have a unique index on my tag table, then I get multiple of the same entries. If I do then the tag model throws an error.

This is my test code:

$content                = new Content();
$content->title         = 'xkcd';
$content->description   = 'description goes here';
$content->url           = 'http://xkcd.com/';
$content->created_on    = new Phalcon\Db\RawValue('NOW()');
$content->tags          = array();

$tagsText = 'xkcd,comics,testing';

$tags = array();
foreach(explode(',', $tagsText) as $tagText) {
    $tag = new Tag();
    $tag->tag = trim($tagText);
    $tags[] = $tag;
}
$content->tags = $tags;

if($content->save()) {
    $app->response->setStatusCode(201, "Created");
    $app->response->setJsonContent($content->overview());
} else {
    $app->response->setStatusCode(400, "Bad Request");
    $app->response->setJsonContent(array('errors'=>$content->getMessagesAsArray()));
}

Contents model:

class Content {
    public function initialize() {
        $this->hasManyToMany(
            'id',
            'ContentsTags',
            'content_id',
            'tag_id',
            'Tag',
            'id',
            array('alias' => 'tags')
        );
    }

    public function getSource() {
        return 'contents';
    }
}

ContentsTag model:

class ContentsTags {

    public function initialize() {
        $this->belongsTo('content_id', 'Content', 'id', array('alias' => 'content'));
        $this->belongsTo('tag_id', 'Tag', 'id', array('alias' => 'tag'));
    }

    public function getSource() {
        return 'contents_tags';
    }
}

Tag model:

class Tag {

    public function getSource() {
        return 'tags';
    }

    public function initialize() {
        $this->hasManyToMany(
            'id',
            'ContentsTags',
            'tag_id',
            'content_id',
            'Content',
            'id',
            array('alias' => 'contents')
        );
    }
}

Example data from the tables:

contents:

+----+-------+-----------------------+------------------+
| id | title | description           | url              |
+----+-------+-----------------------+------------------+
| 11 | xkcd  | description goes here | http://xkcd.com/ |
+----+-------+-----------------------+------------------+

contents_tags:

+----+------------+--------+
| id | content_id | tag_id |
+----+------------+--------+
|  1 |         11 |      1 |
|  2 |         11 |      2 |
+----+------------+--------+

tags:

+----+--------+
| id | tag    |
+----+--------+
|  1 | comics |
|  2 | maths  |
+----+--------+

The models for the unit test mentioned above seem to have no special parameters set, and I can't find the actual table declarations for them so I am at a bit of a loss. The models for the unit test can be seen here:

• Parts
• Robots
• RobotsParts

Answer 1

This was a misunderstanding by me of what the Unit test was doing. I thought it was noticing that "Part 1" and "Part 2" already existed as parts, what it was actually doing was noticing that they had an ID, and hence did not need inserting.

I added this to the Tag class:

/**
 * Look to see if a tag exists, if it does then
 * return it. If it doesn't then create it and
 * return it.
 *
 * @param  string $tagName
 * @return Tag    $tag
 */
public static function getOrCreate($tagName) {
    $tag = static::findFirst(
        array(
            'conditions' => "tag=?0", 
            "bind" => array($tagName)
        )
    );
    if($tag) return $tag;

    try {
        $tag = new Tag();
        $tag->tag = $tagName;
        $tag->save();
        return $tag;
    } catch(Exception $e) {
        $this->appendMessage(new Message($e->getMessage(), 'tags'));
        return false;
    }
}

and altered the test code to this:

$tags = array();
foreach(explode(',', $tagsText) as $tagText) {
    $tags[] = Tag::getOrCreate(trim($tagText));
}
$content->tags = $tags;