CakePHP - How to add associated records to a model on save?

Question

I'm using CakePHP 2.3 and I'm trying to find the correct way to perform associated data saving. I've setup an image upload form that save picture data but in the mean time I also want to process the saved image such that on save my application should examine the file and extract all the exif data and add that tags as associated models tags.

My relations are

Picture hasMany Tags
Tag belongsTo Picture

Right now I'm trying to use the Picture beforeSave callback to programmatically add the new records to the data array but it's not working (it's not saving the added data).

PictureController

$this->Picture->create();           
$this->Picture->saveAll($this->request->data);

Data array after beforeSave

Array
(
    [Picture] => Array
        (
            [field1] => foo
            [field2] => bar
        )

    [Tag] => Array
        (
            [0] => Array
                (
                    [tag] => example
                    [value] => example
                )

            [1] => Array
                (
                    [tag] => example 2
                    [value] => example 2
                )
         )
)

How can I achieve what I want without messing too much with the controller? I would like my business logic to stay mostly on the model.

Answer 1

You need to use deep in order to achieve this. According to the cookbook:

To save also associated data with $options['deep'] = true (since 2.1)

Examples

$Model->saveMany($data, array('deep' => true));
$Model->saveAssociated($data, array('deep' => true));

Check the cookbook for more details