Yii uuid model save returning null for primary key

Question

I'm able to save data to the database and it creates a uuid in the primary key column(id). When I call $model->save(); and access $model->id afterwards, it returns:

{"expression":"UUID()","params":[]}

It should return the actual value in the database...How can I get the actual value that mysql stores?

I have a beforeSave function that adds in the uuid:

public function beforeSave() {
    if ($this->isNewRecord)
        $this->id = new CDbExpression('UUID()');

    return parent::beforeSave();
}

I have also tried creating a trigger that executes the mysql uuid function before update on the id...The $model->id then returns null.

Answer 1

The problem is that you are telling Yii to run a MySQL function to insert into the DB. And it does so just fine, but Yii does not re-read the record afterwards to get the value. To re-read it would be inefficient because what you are doing is not very used and a read from the DB is not necessary usualy. You can go around this in 2 ways:

1) to read the value yourself from the db. You can do a $model->save(); $model->refresh(); right after and you should have the fresh data in the $model

2) you can make your function do a

public function beforeSave() {
   if ($this->isNewRecord)
       $this->id = Yii::app()->db->createCommand('select UUID()')->queryScalar();

   return parent::beforeSave();
}

I have not tested this but you get the idea.

This will go to the DB, run UUID() and return to yii the result. By assigning to $this->id a string instead of a mysql command you will be able to use right away the value without doing a refresh. This will still use MySQL to get the UUID, so it will still put some stress on the server.

Usually I do something like

public function beforeSave() {
   if ($this->isNewRecord)
       $this->hash = hash('ripemd160',microtime());

   return parent::beforeSave();
}

So I do not use the MySQL server at all, but because you use your column as the ID you might want UUID() to generate a truly unique ID.