Relations and find method

[sdrdis]

Lets say I have two models, Model_Test and Model_Tag, Model_Test having a many_to_many relation (named tags) with Model_Tag

$test = \Model_Test::find('first'); // lets say there is at least one Model_Test instance
$test->tags[] = \Model_Tag::forge(array('tag_label' => 'test'));
// <-- If I apply $test->save() here, it works well. $test->get_diff() returns an array with two non-empty elements
\Model_Test::find('first');
// <-- If I apply $test->save() here, the tag relation won't be saved. $test->get_diff() will return an array with two empty elements

[emlynwest]

Going to need a little more information than that ;)

[sdrdis]

sorry, I pressed enter while correcting my title :)

[WanWizard]

This is because the second find will not return a new object, it will return the same object. And the hydration after the find will reset the object to 'retrieved' state by syncing the data and original_data arrays.

Fixing this isn't easy:

• You could ignore the cached object and return a new one (which means you have to objects that could become out of sync, which may be dangerous if you start modifying them)
• You could return the cached object with it's changes (which is probably not what you want most of the time)
• You could throw an exception if the object is in modified state (not very pleasant too)

Besides, get_diff() is an expensive operation, you really don't want to run that on the hydration of every record.

Apart from addressing this, we need to find an alternative solution for 2.0, maybe using a modified flag to track the state of the object.

[sdrdis]

Something strange is that if I do ;

$test = \Model_Test::find('first'); // lets say there is at least one Model_Test instance
$test->title = 'new title'; // old title was "old title"
\Model_Test::find('first'); // or $test = \Model_Test::find('first');
echo $test->title; // still prints "new title"

So the the object is not entirely reset...

[WanWizard]

Checked the code, and is seems it treats relations different from properties. For properties it checks if the object is retrieved from cache, it doesn't do that for relations.

Either way this is inconsistent and needs to be fixed, the question is how (see my previous option list)...

[WanWizard]

I found the solution for option 2 (merging the results in when the object is retrieved from cache), but I'm not happy with it. Sometimes you just want the original record again (without the changes you made before), sometimes you don't (like in your use-case).

Merging results back in also means you do retain additions, but you loose changed objects (the merge will overwrite them), and deleted relations will be restored, which is unwanted in most cases as well.

[sdrdis]

Can't the "from_cache" option be used when you want to specifically retrieve original object ?

[WanWizard]

Yes, that is an option, if you disable the cache, a new object will be created with full hydration of the resultset, this object will not be cached.