Does the Yii CActiveRecord class have a first() method?

Question

I need to just get the first record from a Yii CActiveRecord derived class. In Rails I would just be able to do this:

post = Post.first

I thought I could do the same thing with Yii like this:

$post = Post::model()->first();

But that method doesn't exist. Do I have to just do find with a condition to get the first record?

I don't see first() in the docs for CActiveRecord so I assume the answer is no, it doesn't have a first method. So how would one go about querying just the first record?

This works but sure is an ugly hack. Surely there's a better way.

$first = Post::model()->findAll(array('order'=>id, 'limit'=>1));

Answer 1

Yii isn't going to make any assumptions about how your data should be ordered. Good database design requires that if you use a surrogate key, that key should have a meaningless value. That means NOT using it for ordering.

That issue aside, here is probably the best way to do your query:

$first = Post::model()->find(array('order'=>'id ASC'));

By using find instead of findAll you automatically apply a LIMIT 1 to your result. I would not skip the inclusion of the order by clause, as that insures that the database will order the results consistently.

If you use this query a lot, you can create the following method. UPDATE: Modified it to throw an exception when the primaryKey is composite or missing. We could add more error checking as well, but we leave that as an exercise for the reader. ;)

public function first($orderBy = null){
    if(!$orderBy){
       $orderBy = self::model()->tableSchema->primaryKey;
    }
    if(!is_string($orderBy)){
        throw new CException('Order by statement must be a string.');
    }
    return self::model()->find(array('order'=>$orderBy));
}

Then include this method in a class which extends CActiveRecord, and then extend all your models form that class.

The wrapper I wrote will by default order results by the primary key, but you could optionally pass a different column and direction (ASC OR DESC) if you wish.

Then if you do this for the post class, you can access the first model like so:

$first = Post::model()->first();

Answer 2

CActiveRecord::find() returns only one model.

$first=Post::model()->find();

Answer 3

Yii2 asks for a condition when doing a findOne().

You could do a find() following with no conditions and just return one()

$first= Post::find()->one();

To really be sure you could just add a orderBy clause to it:

$first= Post::find()->orderBy(['id' => SORT_ASC])->one();

Same goes for the command function:

$first= \Yii::$app->myDatabase->createCommand('SELECT * FROM Post ORDER BY id ASC')->queryOne();