如何在CodeIgniter Datamapper中使用cascade_delete配置选项

Question

I use MySQL using InnoDB tables with CodeIgniter Datamapper in my PHP application. Often, the user is given the option of deleting a record through the app by initiating a ->delete function call. When a record has child records (one-to-one or one-to-many), I would also like these records to be deleted along with the parent record, if it is stated by FK constraints in the database.

In this case, I have 2 tables, items and input_lines. I have confirmed that both are using InnoDB. Each item can have many input_lines, so input_lines has a field called item_id, which is set to NULL, indexed, and have FK constraints (ON CASCADE DELETE and ON CASCADE UPDATE). I have set the config element in the DM config file as

$config['cascade_delete'] = FALSE

Because in the documentation it says you should do that if you are using ON UPDATE/DELETE CASCADE. However, when the user initiates the $item->delete() method, only the item is deleted, and the item_id fields on the input_line records associated with the item are set to null.

My models look like this:

class Item extends DataMapper {

  public $has_many = array('labour', 'item_type', 'input_line', 'custom_item_type');

  ...
}

class Input_line extends DataMapper {

  public $has_one = array('item');
  ...
}

I have tried this with cascade_delete = false and true and it won't work. I know the constraints work because deleting the record with MySQL directly works as expected, deleting the child records.

What am I missing? Why is it setting the FK fields to null instead of deleting the record?

EDIT 1:

I decided against my better judgment to debug the delete function in datamapper.php (libraries directory).

I noticed this code in that function:

// Delete all "has many" and "has one" relations for this object first
foreach (array('has_many', 'has_one') as $type)
{
    foreach ($this->{$type} as $model => $properties)
    {
        // do we want cascading delete's?
        if ($properties['cascade_delete'])
        {
        ....

So I var_dumped the contents of $properties, and I saw this:

array (size=8)
  'class' => string 'labour' (length=6)
  'other_field' => string 'item' (length=4)
  'join_self_as' => string 'item' (length=4)
  'join_other_as' => string 'labour' (length=6)
  'join_table' => string '' (length=0)
  'reciprocal' => boolean false
  'auto_populate' => null
  'cascade_delete' => boolean true

It appears the default for when the model doesn't have the property specifically initialized is overriding the config value. This seems like too glaring a mistake so there's definitely something I'm doing wrong somewhere...right? I really, really want to avoid hacking the DM core files...

EDIT 2:

I was thinking maybe the config file wasn't being found, but I checked the logs and there're entries stating that the Datamapper config file was successfully loaded, so that's not the issue.

Answer 1

Doesn't look like anyone has any answers.

My solution was to change the property in the datamapper library $cascade_delete to false, since it's set to true right now. It's unfortunate that I have to resort to hacking the core, but DM won't respect my changes in the config file for cascade_delete so I have no other choice.

If anyone comes across this question and has encountered an issue like this before, please comment.

Answer 2

I have come across the same problem, but finally I just did like this:

$sql = "DELETE FROM EVENT WHERE event_id=".$event_id.";";
$this->db->query ($sql );

In case we set "ON DELETE CASCADE" for the foreign key which refers to event_id, the above SQL works fine, so I just call it directly.